motorcycles and sidecars 7. construction, · pdf filemotorcycles and sidecars 7. construction,...

427

Motorcycles and Sidecars 7. CONSTRUCTION, EQUIPMENT, & OPERATION

CHAPTER VII. Construction, EquipmentAnd Operation of Modern Motorcycles.Features of 1920 Models-

Harley-Davidson Sport Model-

Indian Scout Model-Indian Scout Frame-

Modern Motor Wheel Design-Motorcycle Equipment-

Lighting Systems-How Acetylene Generator Works

Alarms, Tools and Supplies-Harley-Davidson Tool Outfit-

Useful Spare Parts-Carrying Tools and Supplies-General Instructions-

Learn to Control Motor Operating Motorcycles-Motor Control Rules-

Handling Spark Lever-To Start Motor of 1920 Harley-Davidson Models-

To Start the Motor in Cold Weather-

Difficult Starting-Keep Your Eyes. on the Road-

To Start the Machine on the Road-Suggestions for Smooth, Quiet Starting-

To Stop the Machine-To Use the Motor as a Brake-

To Change Back to Lower Speeds-

To Shift from- High Gear to Intermediate-To Shift from Intermediate Gear Into Low-

Instructions for Use of Hand Pump-Use of Muffler Cut-out-

Simple Rules of the Road

428


Features of 1920 ModelsIn essentials, the motorcyclesfor 1920 do not differ radicallyin design front those of previousyears but there has been con-siderable refinement of detail.The modern motorcycle is justas reliable as the automobile,they are better balanced thanthe old types and are more easi-ly controlled.

There is a tendency noted to theuse of a unit power plant suchas found in automobiles inwhich the engine, clutch andchange speed gearing are com-bined in one, this making a verycompact and cleanly assembly.

Pedals have been eliminated onall machines, their place beingtaken by running boards and akick starter is used to start theengine. There are fewer makesof machines on the market, anumber of manufacturers hav-ing discontinued production onaccount of the competition ofthe large producers.

There are only a few active mak-ers left the industry, the promi-nent ones being the makers ofthe Harley-Davidson, Indian,Excelsior, Henderson, ReadingStandard and Cleveland. Thelatter is a new corner that isdeservedly popular and that hasa number of good features, suchas a worm gear reduction drivegear and a two-cycle, singlecylinder engine.

Roller bearings are used inpractically all new engines andvalve sizes have been increased,making for greater efficiency.

The three speed gearset is wide-ly used and several new modelsare doing away with the doublechain drive and using a singlechain from the unit power plant.

The coaster brake is no longerused, its place being taken by afree wheel hub with pedal ap-plied brake .working on the hubbrake drum. The coaster brakeis found on only the early typemachines.

The accompanying illustrationsshow the new type machinesand complete instructions aregiven that will enable the motor-cyclist to care for and operatethe new models, especially thoseequipped with electric lightingsystems.

The operating principles of mo-tors, clutches and change speedgearing have not been altered,so the subject matter relating tothe old machines applies just aswell to the operation of the newunits.

429


Harley-Davidson Sport ModelOne of the new models that isattracting considerable attentionis the Sport Model Harley-David-son which is shown at Fig. 279.In addition to the usual fea-tures, this model has an unusu-al type of power plant as shownat Fig. 280.

The motor in the Harley-David-son Sport model is a balancedopposed four-cycle twin cylindermotor, with a 2-3/4" bore and a3" stroke. This is a piston dis-placement of 35.64 cubic inch-es. Expressed metrically, thebore is 69.84 millimeters, thestroke 76.20 millimeters, and

the piston displacement 584.02cubic centimeters. This motor isa high speed high efficiencymotor conservatively rated at 6horsepower, but developingconsiderably more by actual

dynamometer test. The motor isroller bearing throughout, evento the crank pin bearings, which

430


is an unusual construction,to say the least, for an op-posed twin cylinder motor.The crankshaft is carefullybalanced by means of largecounterweights. The outsideflywheel is built up ofpressed steel discs, and iscompletely enclosed by aneat guard, so that water,sand or mud will not bethrown on to the rider’sclothing.

Having in mind the lowgrade fuels sold under theguise of gasoline, Harley-Davidson engineers de-signed the new opposedtwin motors so as to operatesatisfactory on present dayfuel. The twin-east super-heated manifold will, in-deed, meet with the approv-al of experienced motorcycleriders.

This manifold is a singlecasting which serves forboth the intake and ex-haust passages. By meansof a bypass from the ex-haust pipe, that part of the

431


intake pipe where condensationis most likely to occur, is heatedto a temperature high enough toprevent manifold “loading.”

A careful inspection of this rath-er ingeniously designed mani-fold discloses the fact that theuse of this construction haseliminated all nipples, jam nuts,packing bushings and flangeswhich might cause trouble.

A simple gasket insures a gas-tight joint where the manifoldmeets the cylinder casting prop-er. The carburetor is a standard3/4" Schebler, but it features avery unique attachment in theform of a neat, cylindrical dustbaffle. This is an air filteringdevice which prevents road dustor sand from entering the car-buretor air valve and reachingthe inside of the motor.

Indian Scout ModelAnother interesting machine isthe Indian Scout which is shownat Fig. 281 A and B.

The motor is shown at Fig. 282and the three speed transmis-sion is clearly outlined in thesectional view given at Fig. 283.

With motor, clutch and three-speed gear in one unit and allmoving parts enclosed, the IndianScout is remarkable for cleanli-ness and silence in operation.

The mechanism is positively oil-tight, eliminating splash onrider and the machine itself.

All gears and shafts run in oil andthe valves are completely housedin, making for the utmost silence inoperation. This oil-bathing of theworking parts gives the maximumof life to the parts and guaranteesthe rider the longest possible ser-vice from the machine.

Smooth surfaces on the unit powerplant, combined with its positionabove the lower framework of themotorcycle, further emphasize thefactor of cleanliness.

In the Indian Scout, the L-head,one-piece cylinders with side-byside valves having the Power-plus characterization of maxi-mum power per cubic inch ofpiston displacement are used.

The bore is 2-3/4 inches andthe stroke 3-1/16 inches, givinga piston displacement of 36.38inches. Although rated at 5horsepower, the Indian Scoutmotor develops over 11 horse-power on actual dynamometertests, sustaining high poweroutput for a remarkable periodof time. This ensures the ridergetting the best from his ma-chine under all conditions; re-duces gear shifting to a mini-mum and enables him to travelwith speed and comfort whereother motors would employ alower gear.

The powerplant combines mo-tor, clutch and transmission ina single compact unit, althoughany of these important memberscan be got at independently ofthe others. The power is trans-mitted to the clutch throughspiral gears of great strength,

432


running in a separate oil bath.The clutch is mounted on themain shaft of the transmissionand runs entirely in oil. Thetransmission is in a separatecasing directly behind the motorand is effectively lubricated byits own oil bath.

It is firmly attached to the motorby studs, while the spiral gearsare housed in a casing which isbolted to both transmission andmotor base. Thus the threemembers form one unit. Eachmember is individually cooled,keeping the lubricant at the

proper working temperature andeliminating all possibility ofcarbonized oil from the cylindersreaching and injuring the gearsand bearings.

The powerplant unit is carriedat three points on the motorcy-cle frame.

433


This suspension preventsstrains being transmitted fromthe frame to the powerplant andensures absolute alignment ofall bearings. It also permits the

quick removal or replacement ofthe complete powerplant whensuch course is necessary, andwith the minimum of labor.

434


435


436


Indian Scout FrameConstructed to give the utmostin stress-resistance both lateral-ly and longitudinally with aremarkable lightness in weight,the double tube frame embodiesthe highest form of motorcycleengineering construction.

Two large alloy steel tubes di-verge from the steering headdrop-forging and form a cradlefor the unit powerplant, con-tinuing parallel to the rear ofthe structure.

The unit powerplant attaches bya lug to each of the frame tubesat the front and to a. cross-member at the rear, giving athree-point suspension. Theform of the frame tends to ab-sorb vibrations, thus conducingto easy riding and protecting thepowerplant from strains andshocks.

The steering head is providedwith large ball-bearings, givingmore than ample strength andensuring long life under themost arduous service.

The lines of the frame give evi-dence of great strength yet. inno way detracting from thegraceful appearance of the ma-chine as a whole.

One-piece mud guards of scien-tific form and simple construc-tion amply protect rider andmechanism from road dirt.

The front guard is fitted with flatstays fastened in place by rivets.The rear guard is stayed to theframe and to a luggage carrierwhich performs the double func-tion of carrier and guard brace.

Both gasoline and oil tanks arein one unit. The forward part ofthe tank contains the oil in aspecial compartment in which issituated the hand oil pump,within easy reach of the rider.

This pump has a simple devicefor locking the plunger so that itonly can be operated at the willof the rider. Two large oil pipeslead front the oil compartment,one going to the mechanicaloiler and the other from thedischarge end of the pump tothe motor base.

The gasoline compartment ofthe tank has a capacity of threegallons and is provided with apriming syringe in the filler capand a needle valve for control-ling the flow to the carburetor.The tank is in one piece andrests on lugs on the lower toptube of the frame.

437


Modern Motor Wheel DesignThe motor wheel of Americandesign and construction, whichis shown at Figs. 284 and 285,is a thoroughly practical, self-contained power plant that canbe attached in about five min-utes to any bicycle, either openor diamond frame, and is heldby clamps at. three places.

If it is desired to remove thewheel and use the bicycle alone,the attaching frame need not heundamped from the bicycle, butthe wheel may be released byundoing one lock nut.

The maintenance and open ating cost is extremely low asfigures have been given showingan expense of about $2.50 for1,000 miles use.

The engine is a one cylinder air.cooled form, and develops 1-1/2horsepower. The bore is 2-3/8inches, the stroke, 2-1/4 inch-es. A high tension magnetosupplies ignition current. Thecrankcase is of aluminum andan outside flywheel is used toinsure smooth running.

438


The bearings are improved anti-friction members of the rollertype. The gasoline tank is 2quarts capacity, which isenough for 50 to 60 miles, andis supported by the mudguard.Lubricating oil is carried in the

engine base and enough is sup-plied for 50 to 75 miles. Theattaching frame is of strongsteel stampings and tubing,brightly nickelled. The tire is adouble tube clincher, non-skidtread, 20 inches by 2 inches.

Completely equipped for attach-ing to the bicycle, the attach-ment weighs about 60 pounds.Control is by throttle and com-pression release operated bylevers on the handle barsthrough Bowden wire cables.

439


Motorcycle EquipmentOf the innumerable accessoriesthat have been devised for useof the motorcyclist, either for hispersonal benefit or to be used inconnection with the machine,fully three-quarters are unnec-essary, and can be easily dis-pensed with.

It is not the writer’s purpose todescribe all of the various arti-cles of equipment because theopinions of the various ridersdiffer as to what should be con-sidered necessary and what maybe just as well omitted.

Assuming that the rider hasreceived a bare motorcycle with-out any auxiliary fittings what-ever, it will be well to enumeratebriefly some of the accessoriesthat are really necessary inorder to insure safety and com-ply with the law.

The first thing needed is ade-quate lighting equipment, andin most states a taillight is re-quired as well as a headlight.The next fitting prescribed bylaw is some form of signal or

alarm by which the motorcyclistmay notify other users of thehighway of his approach. Thereis always a certain number oftools and spare parts that canbe carried to advantage and thatare not furnished with the ma-chine.

The equipment of a motorcycledoes not include a speedometerunless one purchases a specialmodel that is sufficiently expen-sive to have the cost of the ac-cessories included in the pur-chase price.

The speedometer, which indi-cates the speed attained, andwhich also includes a mileagerecorder, is a very necessaryfitting.

One is not only able to keep thespeed in accordance with thelegal requirements, but a reli-able speed indicating deviceforms a good check on motoraction and when to oil.

The mileage recorder enablesthe rider to keep track of theservice given by tires or other,parts, and the amount of gaso-

line and oil consumed in cover-ing a given mileage. The cost ofthe average motorcycle speed-meter will be exceeded by asubstantial margin if fines arepaid for just one violation of thespeed law, so it is much betterto insure against, arrest andobtain all the other advantagesby investing in a speedometerthan it is to pay more than thecost of one of the devices toswell the bank account of somerural constable.

Another article of equipment isa watch and holder designed forattachment to the handle bars.Weed chains should be providedfor the tires to minimize skid-ding; they are light and easilycarried as they occupy but littlespace when not in use.

440


Lighting SystemsThe kerosene burning lampsused on the bicycle do not pro-vide sufficient illumination forthe motorcycle, on account ofthe greater speed of the power-propelled form. The variousforms of lamps that are widelyemployed utilize acetylene gasas fuel and throw a brilliantlight which will illuminate theroad for several hundred feetahead of the motorcycle.

The lamp that is most popularin bicycle work is combined withthe gas generator, which is asimple device for producingacetylene gas by the chemicalaction of water on calcium car-bide. While the generator hasbeen widely used, it is beingsuperseded in all eases by thePrestolite tank for motorcyclesin which the gas is stored underpressure, and from which it maybe taken as needed by a simpleoperation of the tank valve.

The searchlight shown at Fig.286 is a separate type whichcan be used in connection with

either the separate generatorshown or the gas tank withwhich all are familiar. A smallgas burning lamp designed forattachment to the rear mudguard is also used when a Pres-tolite tank is fitted.

441


Acetylene Generator SystemsThe method of operation of a gener-ator may be clearly understood byreferring to Pig. 286. As will beapparent, the device consists of twoparts, in upper chamber to holdwater and a lower portion divided intwo compartments, one of whichholds carbide while the other pro-vides space for the gas to collect in.The carbide in the lower chambersurrounds a central tube in whichmeasured quantities of water fromthe upper clamber are allowed todrip. The water is controlled by aneedle valve, and the more wateradmitted the more energetic theliberation of gas becomes.

The gas passes through a coolingchamber at the bottom of the upperportion that holds the water, andfrom there it passes to the burnerin the lamp, through a length ofrubber hose. Alter the carbide hasbeen used up, which is evidencedwhen it has turned from the stateof crystals or lumps to dust, thelower portion of the generator mustbe removed and thoroughly clearedout and fresh carbide insertedbefore one will obtain any more gas.

The latest types of motorcycles areprovided with electric lighting sys-tems similar to those used in auto-mobiles in which an engine drivengenerator charges a storage batterywhich supplies current for lightingand some eases for ignition as well.These systems and their care aredescribed fully in proper sequence.

442


Alarms, Tools andSuppliesOn machines that are pro-vided with electric lighting,it is not difficult to use elec-tric alarms in the form ofvibrating diaphragm hornswhich are set in action by asimple pressure on a pushbutton.

When a machine is not pro-vided with batteries and aloud alarm is desired, amechanical horn such asshown at Fig. 287, A, willproduce a louder tone thanthe usual electric buzzerarrangement. This is a dia-phragm form; and is similarto the type that is so widelyused on automobiles. Adownward pressure on theplunger extending from theback of the horns easingsets the train of gears inmotion whigh, in turn, actu-ate the diaphragm at a rap-id rate. The simpler forms ofbulb operated horns suchas shown at B and C are

443


also adapted for the motorcycle,but these do not provide thebest alarm when touring, inas-much as their note does nothave a very great carrying pow-er. The shriek of the mechanicalhorn can be heard for manyhundred feet.

It is difficult to outline the toolsthat should be provided becauseso much depends upon thecharacter of the machine and itsequipment. Most motorcyclemanufacturers provide the spe-cial tools that are needed to getat any adjustments or nults andbolts that would not be accessi-ble with the ordinary tools ob-tained in the open market, so itwill not be necessary to describethe special socket wrenches orspanners that fit only certainmakes of machines.

The main item of the averagetool kit is a monkey wrench ofspecial, light, thin form that stillhas a large enough opening totake the largest nut on the ma-chine. For instance, if the inlet-valve cage screws into the cylin-der, or if valve chamber caps are

used the wrench should be largeenough to move either of thosemembers, which are usually thelargest of the parts that must behandled by the wrench. A smallsize wrench of the bicycle type isalso convenient and does notoccupy much space.

Two screw drivers should beprovided, one small one with ablade that will permit removal ofthe smallest screws on the ma-chine (such as those on the mag-neto) and one a little larger insize, preferably short and stubbywith a strong blade for handlingthe other members that arescrewed in tighter, and whichcould not be very well removedwith a light screw driver.

A pair of combination pliers areusually part of the equipment,but if these are not provided bythe maker the rider should seethat they are included in thetool outfit. The best all aroundform for motorcycle use is thatwhich is provided with a joint ofsuch form that the openingbetween the jaws may be varied.

The jaws are provided with a flatportion at the extreme end andbelow this part, which is usedfor gripping flat stock, a semi-circular, serrated opening isprovided in each jaw for grip-ping pipe or round objects. Thelower portions of the jaws nearthe hinge are usually sharpenedto a cutting edge and move overeach other with a shearing ac-tion. This portion serves as awire cutter.

One or two small files are alsodesirable, as many occasionsarise where they will prove use-ful. Other tools should be pro-vided depending upon the trans-mission employed. If the V-beltis used, as on some old typemachines, a belt punch or awlas well as several spareconnectors may be included.

If drive is by chain a chain toolfor removing the rivet from thelinks, and a number of spareconnecting links are necessary.

444


Harley-Davidson Tool OutfitA complete tool outfit as sup-plied by the makerof the Harley-Davidson motorcycle is shown atFig. 288. The various pieces are indicated bynumerals and their use is indicated in the follow-ing key:

1. Envelope containing the registration card,which should be filled out and sent to the fac-tory immediately upon delivery of your ma-chine.

2. Envelope containing four washers for changingthe adjustment of the mechanical oiler, as givenin the instructions. Two thick washers BO-320.Two thin washers BO-280. Spark plug adjust-ing gauge EK-1091 is also in this envelope.

3. Extra inner tube valve cap DX-146.4. Extra inner tube valve plunger DX-148.

5. Envelope containing valve parts.

6. Envelope containing powdered mica. Mica tobe spread over repair after repair is completedto prevent tube or casing from sticking to re-pair.

7. Inside blowout patch for temporary repair ofcasings. To repair a small cut in the casing, cuta large enough piece from the roll.

8. Emery paper for cleaning the inner tube whena repair is necessary.

9. Cap EO-747 to screw on oil tank nipple whenfeed pipe is disconnected.

10. Tool box key DJ-721B, for electricallyequipped model.

11. Keys AJ-505A, for tool box on magneto model.

12. Cementless patch for repairing inner tube. Torepair a punctured inner tube cut a large enoughpiece from the patch to cover the puncture.

13. Container for articles supplied with tire kit.

14. Chain tool GK-739, for making repairs to thedrive chain.

15. Wrench AK-2, for rear axle adjusting screwlock nuts.

16. Wrench AK-2, for rear axle adjusting screwsand carburetor low speed adjusting screw.

17. Wrench DK-38, for pedal pill.18. Wrench DK-38, for carburetor gasoline pipe

nut.19. Adjustable pliers AK-269.

20. Screw driver CK-270.21. Wrench GK-65, for exhaust valve lifter pins,

inlet push rod lock nut and all 7/16 inch hexa-gon nuts.

22. Wrench GK-65, for exhaust valve springcover.

23. Monkey wrench DK-809, for general use.24-25. Wrench FK-822, for inlet housing clamp

nuts and crankcase stud nuts.

26-27. Wrench DK-805, for clutch pull rod ad-justing nut and lock nut..

445


446


28. Wrench DK-807, for nuts holding the trans-mission onto frame.

29. Double repair link DK-316, for repairing thedrive chain.

30. Coupling link DK X12, for use when only acoupling link is broken.

31. Half link DR-315, to be used when chain doesnot require a full link.

32. Bosch Magneto Wrench AK-424, supplied withthose models equipped with a Bosch magneto.

33. Berling Magneto Wrench GX-1621, suppliedwith those models equipped with a Berlingmagneto.

34. Wrench DK-S15, the flat steel strip is a gaugeto be used when adjusting the circuit breakerpoints, as mentioned in the instructions cover-ing the care of the Remy generator. Thenotched blade is used to tighten the nuts hold-ing the cables to the coil. The wrench is foradjusting the circuit breaker points.

Useful Spare PartsAmong the spare parts that may be carried toadvantage may be mentioned a small spool ofcopper wire about No. 16 gauge, a length of hightension cable, and a number of assorted bolts,split pins, nuts and washers that conform tothose used on the machines.

If a single cylinder engine is employed as a powerplant two spare spark plugs should be carried,while if it is a twin cylinder, three extra sparkplugs should be included. To insure againstbreakdowns when away from the source of sup-plies, a few spare magneto parts such as the hightension carbon brush holder, a platinum pointedcontact screw and contact breaker bell crank willbe found of advantage.

A roll of tire or insulating tape, and a completetire repair outfit should figure in the equipment.The average outfit for inner tube restoration con-sists of a piece of emery cloth, a tube of cement,and sonic patches of assorted sizes. Patches maybe obtained that do not require any cement as itis already incorporated with them, and a coupleof these may be provided for an emergency wherethe regular cement would not. work properly.

Small tire irons to remove the casing from the rimand an air pump, as well as a number of sparevalve insides, complete the outfit for repairing theinner tube. In case of a blow out, or a serious cutin the outer casing, it will be well to have an in-

447


side blow out patch and a tiregaiter handy. The inside patchis a piece of heavy canvas, 5 or6 inches long and wide enoughto conform to the curved interi-or portion of the tire completelywhen doubled over.

The outer sleeve is made ofleather or rubber and fabric,and is provided with a lacingby which it may be tightlydrawn in place around theinjured portion of the casing.

If going on a tour of any magni-tude, a complete inlet andexhaust valve assembly andseveral extra inner tubes willcomplete the kit.

Carrying Tools & SuppliesThe problem of carrying toolsand supplies is not an easy oneto solve on a motorcycle, thoughmany very practical bags andcarrying cases have been de-signed that will fit the top of theluggage carrier, or that areadapted to be carried one oneither side of that member.

These provide room for consid-erable material and enoughequipment for a trip of somemagnitude may be easily stowedaway. The bag shown at A, Fig.289, is intended for attachmentto the side of the luggage carri-

er, and not only provides a largeamount of storage space insidebut has a smaller tool bag at-tached as well as a pocket tocarry the oil can. The form at Bis intended to be carried on topof the luggage carrier and is

448


considerably larger than thatdesigned for attachment to theside. The bag shown at C is alsointended for the top of the lug-gage carrier, and when flankedon either side with a bag of theform shown at A much storagespace is available.

Where machines are driven bybelt, if one undertakes a longtour and the belt has seen con-siderable service, it may be wellto carry a spare member in aspecial casing such as shown atD. The interior of this case isdivided into two concentric com-partments, the outer one serv-ing for the belt, the inner one tocarry the spare inner tube.

If a sidecar is fitted, an opportu-nity for carrying considerableluggage may be taken advantageof by fitting a luggage carrier orrack, as shown at Fig. 290, tothe back of the sidecar body.

Modern motorcycles have a goodsized tool box included in thestandard equipment.

449


General Instructions forStarting MotorAssuming that the ride has justreceived a machine, and that ithas come crated, and also thathe is not familiar with motorcy-cle operation, we may give thefollowing general instructions:

After the machine has beenuncrated, and the handle bars,saddle and pedals attached intheir proper places, the firststep is to see that the tanks arefilled with gasoline and oil. .

As a rule, the filler caps are veryplainly marked to indicate thepurpose of the container towhich they are fitted. In fillingthe tank with fuel, filter thegasoline by passing through achamois skin which insurespositive removal of all dirt andwater.

Be sure to fill the oil tank withthe proper grade of lubricant,which must be a good air-cooledengine cylinder oil, and prefera-bly of the brand recommendedby the maker of the machine.

450


Before attempting to start themotor, become familiar with thevarious parts of the controllingapparatus.

In most American machines thegas supply is regulated by oneof the movable grips on thehandle bar, and which one it iscan be easily ascertained bymoving both of them in turnand seeing which operates onthe throttle lever at the top ofthe carburetor.

In some machines, the grip isturned in one direction to closethe throttle which would bejust the same as that to openthe throttle in other motorcy-cles. The proper mode of proce-dure can only be determined byexperiment.

The grip on the other handlebar is used for advancing thetimer or contact breaker of themagneto when turned in onedirection and for raising theexhaust valves if turned to theother extreme position.

In some motorcycles, the ex-haust valves are raised by a

special lever carried by the han-dle bars. The clutch of mostmotorcycles is operated by ahand lever at the side of thetank, and in some machines asmaller lever will be mounted atthe side of the tank that is con-nected directly with the contactbreaker of the magneto.

When a two-speed gear of theplanetary type is used, a single-control lever usually serves tocontrol both high and lowspeeds, and this member corre-sponds to the usual free engineclutch actuator.

When an individual or shiftingclutch, two-speed gear is used,the master or friction clutch isoften shifted,by a foot lever,while the speed changing is ef-fected by a suitable lever carriedon the upper frame tube.

Learn to Control MotorThe first thing to do is to learnto control the motor. To do this,raise the rear wheel of the ma-chine from the floor by thestand provided for that purpose,open the valves in the gasolineline so the fuel will flow to thecarburetor and supply a coupleof pumpfuls of oil to the enginebase.

Prime the carburetor by press-ing the priming pin and holdingthat member down until gaso-line flows from the bottom of thedevice. This shows that thespray nozzle has overflowedwhich indicates that it is clear ofdirt.

Set the spark about half wayadvanced, open the throttleslightly, and raise the exhaustvalves by whatever means areprovided for that purpose. Pedalbriskly and turn the motor overat a fair rate of speed, and thendrop the exhaust valves and themotor should start.

After the motor has been start-ed, become familiar with the

451


action of the spark and throt-tle levers or control grips bymoving them back and forth,and noting the effect of thevarious positions on the be-havior of the engine. Do notrun the engine unnecessarilyfast when on the stand.

Instructions for OperatingMotorcycleAfter having learned to manipu-late the motor and control itsspeed on the stand. the motormay be started and allowed torun slowly, and the high-speedor free-engine clutch lever maybe set in the free engine posi-tion. This may be clearly noted

by pressing on the brake pedalwith the engine in motion.

If the rear wheel stops rotatingwithout affecting the enginespeed, it indicates that theclutch is free and functioningproperly. If applying the brakesstops the motor as well as therear wheel, it shows that theclutch is not properly released,which may mean that the lever

452


is not in the proper position orthat there is some defective con-dition in the clutch itself. Themachine is then dropped off ofthe stand with the clutch lever inthe off position, and, after therider has mounted, the enginemay be speeded up and theclutch lever moved gradually untilthe motorcycle acquires a certainmomentum, after which the

clutch may be engaged positively.

If the machiucc is a two or threespeed form, the start may bemade on the high speed withoutany trouble if the ground islevel, as the friction clutch willprovide gradual application ofpower if it is controlled properly.

When starting on a hill or insand, it will be well to start on

the low gear and throw into thehigh only when the top of thehill is reached, or road condi-tions become more favorable.

Do not slip a clutch of any typeunnecessarily, because this willproduce wear of the frictionsurfaces, so it is best to start onthe low speed under any condi-tions. In operating change-speedgears of the shifting clutch type

453


or of the sliding gear pattern, al-ways be sure that the masterclutch is completely released beforeendeavoring to shift gears.

When shifting from high speedto lower speed, always slowclown the engine or wait untilthe speed of the motorcycle

drops to the point that will cor-respond to the gear ratio ob-tained by the reduction gearing.’

In changing from the low to thehigh gear, accelerate the engineslightly to speed up the machinebefore the shift is made.

454


Motor Control RulesAll motorcycle motors have acertain degree of flexibility, i.e.,they may be run slow or fast,and the speed may be accelerat-ed or cut down as desired withina range from 200 revolutionsper minute to the maximum,2,500 or 3,000, which will varywith the type of motor. This isan important advantage, inas-much as it permits one to regu-late the cycle speed on mostoccasions by a touch of thethrottle grip alone.

The engine speed of practicallyall motorcycles is controlled bytwo ways, though usually theseare employed in conjunction.One of these consists of varyingthe time of the spark in thecylinder, the other regulatingthe amount of gas supplied.

The spark and throttle levers,while designed to be manipulat-ed independent of each other,usually move with a certaindefinite relation. It would not begood practice to run an enginewith the spark lever way ad-

vanced and gas supply throttlenearly closed; nor would goodresults be obtained if the sparklever was retarded and thethrottle opened, as it is desiredto increase the motor speed.

It is not difficult to understand thefunction of the throttle lever andhow the admission of more gas tothe cylinders would act in creatingmore power, just as augmentingthe steam supply to a steam enginewill increase its capacity.

The rules for manipulation ofthe spark lever are not so wellunderstood. In order to makeclear the reason for intelligentmanipulation of the spark han-dle, there are certain points thatmust be considered.

On most, motorcycles, there is aposition of the spark lever atsome point of the are over whichit moves which corresponds tothe normal firing point.

If the spark lever is not ad-vanced beyond this position,and the motor is turning overslowly, the gas in the cylindersis being exploded when the

pistons reach the end of theircompression stroke. When thegas is fully compacted, the ex-plosion or power obtained fromcombustion is more powerfulthan of the spark fired gaswhich was not compressedproperly.

The electric spark is not pro-duced at the exact time that themotor should be fired at allspeeds, and if the spark was.supplied the very instant of fullcompression, irrespective of thespeed of rotation, there wouldbe no need of moving the sparklever.

Not only is the current apt tolag, but it takes a certain defi-nite amount of time to set fire tothe gas. It requires the sameamount of time to ignite the gas,of given composition, regardlessof the speed of the motor. of themotor is only turning at a fewhundred revolutions per minute,there is ample time to ignite allgas charges positively, but if themotor speed increases and theexplosions occur oftener, thenone must compensate for the

455


more rapidly occurring combus-tion periods by arranging tostart igniting the gas earlier sothe explosion will occur whenthe piston is at its highest pointin the cylinder.

The compensation for lag ismade by advancing the spark.The spark lever on the handlebar or tapic moves a commuta-tor, if battery system is em-ployed, or the magneto contactbreaker box, if that form of cur-rent producer furnishes theignition energy. The amount ofspark advance needed dependson engine speed and the greaterthe piston velocity the more thespark should be advanced.

Handling Spark LeverIt is possible to advance thespark lever too far, and, whenthis occurs, the gas is explodedbefore the piston reaches thetop of its stroke, and prematureexplosion takes place. As a re-sult of this, the upwardly mov-ing piston is forced to overcomethe resistance exerted by the

expanding gas of the ignitedcharge in completing the re-mainder of the compressionstroke, and before it will returnon the power stroke. The injuri-ous back pressure on the pistonreduces the capacity of the mo-tor and a pounding noise similarto that produced by loose motorparts gives positive indication ofpremature ignition due to exces-sive spark advance.

On the other hand, if the sparklever is not set as far forward asit should be, the explosion maybe late because of the “retardedspark.”

If the spark occurs late in thecycle, the charge is not fireduntil the piston has reached itshighest point and after it hascompleted a small portion of itsdownward movement.

As the point of maximum com-pression is passed and the pis-ton moves down in the cylinder,the size of the combustionchamber augments and the gasbegins to expand again before itignites. Owing to the moderate

compression, the power result-ing from explosions is less thanwould be the case with a higherdegree of compression.

To secure power, it is necessaryto supply more gas to the cylin-ders. Driving with a retardedspark produces heating of themotor and is wasteful of fuel.

For ordinary running, the sparklever is usually placed aboutmidway of its travel on the sec-tor, and as a general rule anengine with magneto ignitiondoes not require the frequentmanipulation of the spark nec-essary when current is pro-duced by chemical means.

As the engine speed increases,the current produced by themagneto is proportionately aug-mented, and the spark leverneed not be advanced from thecenter position except underconditions which permit of ex-ceedingly high engine speeds.

Summing up, it will be patentthat the greatest economy offuel will result when the motor-cycle is operated with as little

456


throttle opening as possible, andwith the greatest spark advancethe motor speed will allow.

To obtain maximum power, asin hill climbing on the directdrive, the spark lever shouldnever be advanced beyond cen-ter and the throttle should beopened as wide as possible.

For extreme high speed, the sparkis advanced as much as possibleand the throttle opened wide.

457


To Start 1920 F and J Harley-DavidsonsThe beginner may find it easier to start the motorwith the machine on the stand. He does not haveto balance the machine this way. However, besure to put the gear shift lever into neutral posi-tion or disengage the clutch by pulling the handlever shown in Fig. 295, over, way back beforetaking the machine off the stand.

1. Release the clutch by pulling the clutch handlever back all the way, or by pressing the heelof the foot down on the rear part of the clutchpedal.

2. Put the gear shift lever in the position marked“Neutral.” The lever will generally go into thisposition very easily if the clutch lever is all theway back, but if the transmission gears hap-pen to stop so that the teeth are opposite eachother, it, will be necessary to turn the gearsover by giving the starter pedal a stroke, or byturning the rear wheel slightly.

Do not under any circumstances try to force thegear shift lever because damage will result. Thegears will always shift easily if the shiftingmechanism is properly lubricated at the variousplaces provided for oiling.

3. After the gear shift lever is in neutral position,engage the clutch by pushing the clutch handlever forward all the way, or by pushing downon the forward part of the clutch foot pedal.

4. To facilitate starting, close the carburetor airvalve by pulling out the bottom “B” (see illustra-tion Fig. 296) and give it a slight turn to the left.There are three positions that this button canbe put into to readily control the tension of theair valve spring.

In very cold weather pull the button way out asin position marked “3.” After the motor isstarted, turn the button still further to the leftuntil the pin drops into position marked “2.”Then start the machine in the regular way.

Leave the stem here until the motor starts tomiss, then release the stem entirely by turning

458


459


the button still further to the left, until the pindrops into position marked “1.” This is the posi-tion the button should always be carried inafter the motor has warmed up.

5. Close the throttle by turning the right handle-bar grip to the extreme right and then open itslightly by turning the grip slightly to the left.

6. Turn the left grip to the left as far as possible,raising the exhaust valves, thereby relieving thecompression in the cylinders.

7. Give the step starter pedal a vigorous strokedownward, at the same time turning the leftgrip to the right one-half or two-thirds of theway, thereby dropping the valves and advancingthe spark. After the motor is running, advancethe spark fully by turning the left grip all theway to the right, release the air valve stein andclose the throttle. .In starting the electrically equipped model 20-J,care should be taken that the left grip is not ad-vanced more than one-half or two-thirds of theway. If it is advanced more than this, the motormay backfire. Sometimes the magneto model 20-F will start more easily if the spark is advanced allthe way. The exact spark advance necessary tostart the motor quickest and easiest will be ascer-tained after a few trials.

8. If the motor is warm, it should start on thefirst attempt. If it. does not, repeat the opera-tions as mentioned above. Do not race the mo-tor on the stand.

Some motors will start more easily if thethrottle is not quite closed.Some experienced riders prefer to start themotor “against compression.” This is done byadvancing the spark about half way and closingthe throttle either all the way or almost all theway and then using the starter pedal. Whichever way is selected by the owner after he getsaccustomed to his mount is a matter of prefer-ence or individual knack.

9. To stop the motor in model 20-F, or 20-.J, turnthe left grip all the way to the left. On the elec-trically equipped model 20-J, also try to soundthe horn as soon as the motor has stopped, tomake sure that the centrifugal switch hasopened the battery and generator clutch. If thehorn can be sounded with the motor idle, dis-connect the ground wire from the battery boxcover screw to prevent discharging the batteryand then apply the instructions under “To Ad-just the Centrifugal Switch” in the chapter onElectric Lighting.

After you have started the motor a few times on thestand, learn to start it with both wheels on theground, either by straddling the machine or stand-ing alongside of it. The starter crank describes avery large are, turning over the motor with sufficientmomentum to, generally start it on the first stroke.Of course, until you acquire the knack of using thestarter crank, you may have to make a few trials.Start the motor as naturally as possible.

460


Start Motor in Cold WeatherTo facilitate starting in coldweather the motor should beprimed; that is, gasolineintroduced directly into thecylinders through the cylinderpriming cocks. The reasons whya motor does not. start readilyin cold weather are these:

Gasoline does not vaporizereadily when mixed with coldair. The term “raw” is applied toa mixture of gasoline and coldair. It is advisable to use highertest gasoline in winter than insummer.

Oil congeals or becomes practi-cally solid in cold weather. If amachine is standing in the cold,the oil congeals between thecylinders and pistons and in thebearings. This makes it difficultto crank the motor.

By priming the cylinders withgasoline, the thick oil is immedi-ately turned into liquid formallowing easy cranking.

For this reason the followingrecommendations are offered forcold weather starting:

1. Unscrew the knurled buttonof the primers located on theleft side of the cylinders nearthe top, about two turns.

2. Charge the priming gun,which is a unit with one of thegasoline tank caps, by draw-ing the plunger button out toits full extent.

3. Place the point of the priminggun into the opening of theprimer and give it the chargeof the gun. Prime the othercylinder in the same way.

4. Close the primers.

5. Hold down thecarburetor,float primer untilthe carburetor overflows.

6. Tighten the easy startingtension spring of the carbure-tor auxiliary air valve by pull-ing out the button “B” andgiving it a slight turn to lock it.Start the motor.

After the motor is warmed up,loosen the tension spring on thecarburetor. If the carburetorchokes, do not release the stementirely. Drop it into recessnumber “2,” illustration Fig.296, and leave it here until themotor misses, due to the richmixture, then release it entirelyby dropping it into recessmarked “1.”

461


Keep Your Eyes On the RoadOne thing the beginner must bearin mind at all times is that underno circumstances must he takehis eyes from the road ahead.

The gears must be shifted or theclutch released or engaged by thesense of touch, and the soonerthe rider learns to operate thesecontrols correctly, the sooner hewill be safe on the road.

It is true that many old ridersare negligent on this score, andoften take their eyes off theroad, but it is a careless act andninny accidents can be traceddirectly to this cause.

Difficult StartingFrequently difficult starting isdue to nothing more than dirtyor poorly adjusted spark plug.As soon as difficulty in startingis experienced remove the plugs,inspect and clean.

Clean the points and polish withvery fine sand paper or emerycloth. Adjust the clearance of thepoints with the gauge furnishedwith the machine for that pur-pose. The gauge measures .022inch in thickness and its use isshown at Fig. 297.

Fig 297 - Gauging Spark Plug Gap

462


To Start the Machine Onthe RoadAssuming that the motor isstarted as per previous instruc-tions, the first thing to do is torelease the clutch by pullinghack the clutch hand lever orpressing on the rear part of theclutch foot pedal, and then shiftthe gears into first or low speed,by moving the gear shift leverinto position marked “Low.” Ifthe motor was started on thestand, the gears must. be inneutral or the clutch releasedbefore the machine is taken offthe stand. (See Fig. 298.)

Next, let in the clutch very gradu-ally by pressing the toe on theforward part of the clutch footpedal, or, if preferred, by movingthe clutch lever forward by hand.

For the first ride or two, do notbe afraid to run in low gear for100 feet or so. After the ma-chine is under way and youhave it in good balance, releasethe clutch all the way, quicklyclose the throttle and move thegear shift lever through neutral

into position marked “Second.”

Then engage the clutch againslowly, as before, at the sametime, opening the throttle slight-ly. After running 50 feet or so, itwill be easy to shift into highspeed or direct drive by againreleasing the clutch, closing thethrottle and setting the gearshift lever into position marked“High.”

Then again open the throttlewhile engaging the clutch, allow-ing the machine to get awaysmoothly and quietly. Duringthis time the spark is beingcarried practically fully ad-vanced.

463


Suggestions for Smooth,Quiet StartingWith a little practice the beginnerwill learn just how far the throttleshould be opened while engagingthe clutch, enabling him to getaway as smoothly and quietly asthe highest class cars.

Never race the motor while run-ning idle. To say that this prac-tice is to be condemned is put-ting it mildly for these reasons:The motor will sooner or latershow the effects of having beenabused. If the motor is racedwhile starting the machine, theclutch is being slipped unneces-sarily, meaning friction andwear, and the rear tire is undera terrible strain.

Another objection is the noise of themotor while the machine is gettingunder way. Take a pride in makinga smooth, quiet get-away and youwill command the respect of yourfellow riders and the general public.The Harley-Davidson motorcycle ispractically noiseless. Why incurcriticism, giving yourself and ma-chine a black mark?

Never let your rear wheel spinunder any conditions. Whenstarting, use extreme care to seethat the clutch is engaged grad-ually enough so that there is nogrinding of the rear tire on theroad. Owing to the tremendouspower transmitted to the rearwheel when low or second gearis being used, it is an easy mat-ter to spin the wheel. This plac-es a terrific strain on the tireand the practice, if persisted in,will rapidly wear out the tire.

To Stop the MachineIn learning to operate a motor-cycle one of the most importantthings to bear in mind is thatthe ability to stop the motorcy-cle quickly is occasionally ofgreat importance.

After a few weeks use the riderwill find that the actions neces-sary to bring the motorcycle to astop, come about almost uncon-sciously at the first. sign of anobstruction ahead or other ne-cessity for a. quick stop.

Possibly the brake is subject tomore abuse than any other partof the motorcycle, simply becausemany riders seem to take delightin seeing how close they canconic to the stopping point at highspeed, before they shut off themotor and apply the brake.

Do not form the habit of apply-ing the brake suddenly andbringing the motorcycle to astandstill in a short distance.

The rider who can shut off hismotor at some distance from thepoint where he desires to stopand coasts up to it, applying thebrake gradually, thereby bring-ing the motorcycle to a gracefulstop, shows good judgment fromevery standpoint. No one whotakes pride in keeping his ma-chine in tiptop condition willstop suddenly except in ease ofemergency.

The proper way to stop the mo-torcycle is to release the clutch,closing the throttle at the sametime, and then stopping by care-ful and gradual use of the brakepedal. Never jam the brake on,

464


if it can be avoided. To stop themotors of all 1920 models turnthe left. grip to the left as far aspossible, thereby raising thevalves and relieving the com-pression.

It is not uncommon to hearriders complain that they arenot getting the right kind ofservice from their tires. Theywill even claim that a casing hasbeen ruined in three or fourhundred miles of riding. Invari-ably this is the rear casing andinvestigation will demonstratethat almost without exception,riders making complaints of thisnature have been abusing thetires and the braking mecha-nism by sudden stops or quickstarts.

Excessive tire wear can oftentimes be traced to fast ridingover rough roads, which give therear wheel an opportunity tospin. Every time such spinningtakes place a certain amount ofrubber is worn off the tread ofthe tire.

To Use the Motor As a BrakeIn riding down long steep hills itis sometimes advisable, in orderto save the brake and keep itfrom getting heated, to use themotor as a brake.

To do this does not require stop-ping the machine and a newrider will soon adopt this meth-od. .Just before descending ahill, disengage the clutch, closethe throttle and at the sametime shut off the motor.

As soon as the motor is stopped,both grips should be turnedinward so as to get: as muchcompression as possible in thecylinders. Then push the clutchlever forward just far enough.not to turn the motor over.Having this slight drag at theclutch will greatly retard themomentum of the machine andwill naturally save the brakeconsiderably.

Before descending extremelylong steep hills put the gearshifter lever in low gear positionand apply the above instruc-tions. Under this condition won-

derful braking power is received,only care should be taken thatthe clutch is not engaged farenough to turn the motor.

465


To Change Back To LowerSpeedsA11 ordinary grades can ofcourse be negotiated on highgear without trouble if the ma-chine is traveling at a fair speed.If it is necessary to slow up on agrade for traffic, or for someother reason, and the motorbegins to knock, the sparkshould be retarded a trifle. Ifthis does not. remedy theknocking, the spark should heretarded still further; then if themotor continues to knock, thetransmission gears should beshifted from high into intermedi-ate or low. A sectional view ofthe gearset is given at Fig. 298.and also at Fig. 299, over.

The knowledge of the correcttime to make this shift will cometo the rider only through experi-ence. Not only is it an easy mat-ter to stall the motor by attempt-ing to negotiate a hill on highgear, when the laboring of themotor indicates that intermedi-ate or low gear should be used,but it is a tremendous strain onthe entire power plant.

466


Fig 299 - Gear Change & Clutch Assembly -Harley=Davidson MC

467


To Shift from High GearInto IntermediateWhen it becomes necessary tous intermediate gear, the clutchshould be released and the gearshift lever moved from high gearposition straight through intointermediate or second speedposition with a quick firm move-ment, after which the clutchshould be engaged again asquickly as possible but withoutany perceptible jerk.

The change from high gear intointermediate is generally madeafter the rider has retarded thespark, therefore it is necessaryto advance the spark when theintermediate gear is engaged.

It will not take the rider long tobecome acquainted with thecontrol of the machine, so thathe will know just when to throt-tle the motor to prevent it fromracing while shifting gears.

To Shift from IntermediateGear Into LowOccasionally you will encountera hill so steep that the machinewill not negotiate it, even onintermediate gear, without, themotor slowing down.

In this case, low gear or firstspeed must be called into ac-tion. To make this change, it isonly necessary to release theclutch, shift the lever forwardfrom second into low and againengage the clutch, similar to themanner in which the shift wasmade from high gear into inter-mediate.

It must be remembered that it isnecessary to have the sparkadvanced after a shift. into alower gear. This is an importantpoint because an advancedspark lends to keep a motorcool, while a retarded sparkwill soon cause a motor to heatup unnecessarily. For thisreason the rider should neverattempt to run the motorcyclefor any distance with a retard-ed spark.

A little difficulty may be encoun-tered at first in shifting gears.especially on a hill. A little prac-tice will enable the rider to be-come expert so that gears maybe shifted easily and without asound.

Under no circumstances run anew motor at high speed until ithas covered several hundredmiles and is thoroughly “run in.”

468


Instructions for Use ofHand PumpWhen climbing a long hill, orpulling through long stretches ofsand or mud it is often advis-able to give the motor a littleextra oil with the hand pump.

A third of at pumpful or a halfpumpful is enough if the hill orbad stretch is not a very longone.

On a very long hill or badstretch it is better to give themotor this extra supply of oil alittle at a time, say, one-third ofa pumpful, than it is to give itan entire pumpful at one time.This is true especially if themachine is carrying a loadedsidecar.

To Turn CornersThe confidence necessary toturn a corner nicely comes onlywith experience and the newrider should turn all cornersvery slowly and cautiously toavoid falling, especially if theroad is wet.

469


SkiddingThere is absolutely no excusefor skidding under ordinaryconditions, but skidding mayoccur on slippery surfaces or inrounding turns at high speed,even on dry surfaces, if the rideris careless.

Not only is skidding-dangerous,but it causes excessive tirewear. Sometimes on a roadwhich has a high crown thenmehiue may slow a tendencyto skid if the surface is very wet,even when running straightahead.

This tendency will be minimizedif the rider keeps to the middleof the road or where the road isthe highest. When traffic condi-tions prevent this, great cautionshould be exercised to ride at amoderate pace or a fall mayresult.

Sometimes the rider may feelthe machine starting to skid. Anexperienced rider eaii some-times stop a skid by turning thefrontwheel in the same direc-tion in which the rear wheel is

sliding, but it is only an experi-enced rider who can do this,and the better plan to follow isto take precautions to preventa skid in the first place.

Use of the Muffler CutoutOne thing which has given mo-torcyeles and motorcycle ridersa great amount of undesirablepublicity is the fact that someriders persist in riding with themuffler cutout open.

This may have been excusablein the early days of the sportwhen some motors were notpowerful enough for even ordi-nary touring conditions, and therider because of this fact openedthe cutout to relieve the backpressure caused by the inet-ticient mufflers of those days.The Harley-Davidson muffler isa very efficient piece of mecha-nism and causes no appreciableback pressure in the motor.

It has been proven by dyna-mometer tests at the factorythat the difference in powerbetween using a closed mufflerand an open cutout is less thanone per cent. Therefore, there isno reason whatever for the rideropening the muffler cutout un-less it is desired to locate a missin the motor.

470


Simple Rules of the RoadWhen meeting any vehicle fromthe opposite direction, it is therule of the road in the UnitedStates for both vehicles to keepto the right.

In no place is courtesy moreappreciated, or a better indica-tion of good manners, than onthe road.

If a motorcycle rider wants topass another vehicle, it is ofteneasier for him to turn out of theway, than for the other vehicleto turn out. The motorcycle willnegotiate a. bad piece of roadbetter than any other vehicle,and motorcycle riders as a ruleare always glad to accommodatemore cumbersome conveyances.

In overtaking a slower goingvehicle traveling in the samedirect ion, pass the vehicle onthe left.

No considerate rider will annoyor frighten pedestrians by im-proper use of the horn of warn-ing signal.

It has become the accepted rulein many localities to hold one’sleft arm to the left when turningto the left, or when turning tothe right to extend one’s rightarm in that direction.

It is a good plan to look up thelocal traffic laws or ordinancesgoverning motorcycles; then youwill be on the safe side.

motorcycles and sidecars 7. construction, · pdf filemotorcycles and sidecars 7. construction,...

Documents