Explanation of Gear Control.

Before attempting to start the engine the gears must be in " neutral " (free-engine position). To check this raise the clutch lever and depress the kickstart. If the machine tends to move forward due to the pressure on the kickstart one of the gears is engaged and neutral must be selected.

To find neutral the gear control pedal must be moved up or down and several times in succession, depending upon which gear is engaged, in accordance with the following explanation.

The control pedal operates a spring loaded spindle within the gearbox. A carrier on the spindle, and moving with it, carries a pawl which, as the spindle moves one way or the other, engages ratchet teeth and thus moves the gear operating cam plate a set distance. The range of movement of the spindle is limited by stops in the mechanism. The cam plate is locked or " indexed " at the end of each movement by another spring loaded pawl engaging in notches cut in the edge of the cam plate. There are five notches, one for each gear and one, between the first and second gear notches, for neutral position in which there is no drive through the gearbox.

After each movement the gear pedal must be allowed to return to its central position by the action of the centralising spring.

If first (low) gear happens to be engaged, neutral would be found by depressing the pedal gently for just half of the possible travel from the normal position. Depression of the pedal to the limit in such circumstances would select second gear. A second downward movement to the limit would engage third gear, and another movement in the same direction would select fourth (top) gear.

Thus to obtain neutral from top gear the pedal would have to be raised twice in succession (moving it to the limit and releasing it each time) and then raised gently for half distance. Three successive full upward movements and releases would engage first gear.

The novice can best understand this by raising the machine on the centre stand, sitting alongside the machine and selecting the gears one after another by hand, while the engine is stationary. Remember however that when experimenting in this way it is unlikely that more than two gears will engage straight away and without moving the driving dogs, which have to interlock, by turning the rear wheel a little either way. The driving dogs often come to rest opposite each other, in which position no amount of force on the pedal will make them engage.

Having selected neutral start the engine.

Starting the Engine. Turn on the fuel, using for preference the right-hand side tap. Flood the carburetter sparingly by depressing the " tickler " on the float chamber top (see 21 illustration page 57) or by leaning the machine at a steep angle to the right for about twenty seconds.

Do not flood the carburetter excessively. To flood so that fuel overflows from it is quite unnecessary and is wasteful.

DO NOT FLOOD AT ALL WHEN RESTARTING A HOT ENGINE.

Close the air lever three-quarters of its travel (leaving the air valve a quarter open) and set the throttle so that the throttle valve is not more than ¹/₈-in. open. Further opening will reduce the depression on the pilot system and make the mixture too weak to give an easy start. Raise the exhaust valve lifter lever on the handlebar and whilst holding it up depress the kickstart slowly. After a small movement the ratchet will engage the ratchet gear on the layshaft and the crankshaft will be rotated on further depression of the kick-start.

Release the kickstart when it reaches the bottom and repeat the movement several times quickly to draw combustible mixture into the cylinder and free the engine.

After this, release the exhaust valve lever and depress the kickstart slowly. As the kickstart moves down resistance will be felt due to the compression of air and fuel vapour in the cylinder. Upon feeling this raise the exhaust valve lifter and move the kickstart very slowly to the bottom of its travel. This must be done slowly to avoid spinning the flywheels further than is needed and we stress the point as being important. Bring back the kickstart to the top, and after engaging the ratchets by making the first movement slowly, thrust it smartly downwards without this time touching the exhaust valve lifter. It will be found that the crankshaft will turn several times and the engine should start.

Keep the hand off the twist grip when starting as the action of pushing down the kickstart tends to jerk the hand and open the throttle involuntarily, causing weakening of the mixture and making starting unlikely.

If the engine does not start at once, depress the kickstart again against compression, ease the piston over compression slowly using the exhaust valve lifter as already described, release the kickstart and valve lifter and try again.

Although as described this method of starting may seem lengthy and complicated, a little practice will soon enable it to be performed automatically.

Be sure never to kick sharply before engaging the ratchets properly otherwise the crank may slip and cause damage to the ratchet teeth. It will be noticed that as the kickstart crank moves downwards it moves across the face of the disengaging ramp formed on the bearing housing, and the ratchet moves inwards under pressure from the internal engaging spring.

Careful and deliberate movements in conjunction with the correct throttle opening will give better and quicker results than continued rapid kicking.

Release the kickstart immediately the engine starts. The ratchets make a little noise just before disengaging when the engine is running, and this has occasionally caused enquiry. It is quite normal and can be disregarded.

After a few moments' running, open the air valve gradually, otherwise the engine will begin to fire irregularly, usually missing about every other beat (eight stroking) and black smoke will come from the exhaust.

After starting a new engine, or if the main oil feed pipe has been disturbed, the oil circulation must be checked. See page 28.

All normal running is done with the air valve full open. Do not close it when restarting a hot engine.

Obstinacy in Starting.

During cold or damp weather, the engine may fail to start because the high tension cable is wet and dirty or the outside insulation of the sparking plug coated with mud. This provides a path for the high tension current from the magneto to leak to earth and diminishes the intensity of the spark at the plug points. Clean the affected parts with a dry rag.

Excessive flooding of the carburetter in a cold engine, normal flooding when hot, or leaving the machine leaning over to the right with the fuel turned on, can all make the mixture too rich to fire readily and will prevent starting. Rectify by opening the throttle and air controls fully and rotating the engine several times as quickly as possible with the kick starter to clear the over-rich mixture from the cylinder. In an extreme case of over-flooding the fuel should be turned off until after the engine has started.

After clearing as described, close the twist grip, and, leaving the air control full open, make another attempt to start. If unsuccessful, take out the sparking plug, and clean the internal insulation and firing points thoroughly. They may be " wet " with unvaporized fuel. Check the point gap and if necessary reset to .018" to .023" and rotate the engine several times to clear the combustion chamber before replacing the plug.

Provided that the trouble is not of a more serious nature necessitating workshop attention the engine should start.

Moving off.

Allow an engine which has been started from cold to run a few moments before running it up to high speed. A fast idling speed is best, and will allow the oil time to reach all parts.

It used to be the rule to run an engine very slowly to warm it up, but nowadays it is considered better to drive off without any lengthy preliminary warming up. Obviously a machine just started from cold should not be opened up to high speed right away even if the engine has been run in.

The method of running in a new engine is explained later.

Push up the stand and free the clutch by gripping the clutch lever and bringing it back into contact with the handle¬bar grip. Raise the gear control pedal to engage first gear. The driving dogs are engaged when the indexing pawl is felt to spring into the notch in the cam plate. They may not engage or interlock at the first attempt, but can be made to do so without excessive force by keeping light upward pressure on the pedal whilst moving the machine backward or forward a little, when the pedal will be felt to move upward as engagement takes place. Another method is to release the gear control pedal and momentarily re-engage the clutch which will alter the positions of the dogs, and then try again.

Never in any circumstances operate the gear control pedal when the engine is running unless the clutch is disengaged first.

Having engaged first speed (low gear) as described, begin to release the clutch lever very slowly and gradually, and at the same time open the throttle a little at a time, increasing the throttle opening as the clutch begins to engage.

Nearly all learners make the mistake of releasing the clutch lever completely as soon as they feel the clutch " bite," and the machine begin to move forward, with the result that either the engine stalls or the machine moves off in a series of jerks. The temptation to release the lever suddenly at this stage must be resisted and it must be released gradually all the way and the throttle opened progressively as the machine moves off.

It will be obvious from watching a skilled rider that a smooth start depends upon the co-ordination of two movements : opening the throttle and engaging the clutch together.

Too sudden engagement of the clutch with the throttle not open far enough will stall the engine. On the other hand excessive throttle opening and hesitant release of the clutch will permit the engine to race.

The novice is advised whilst learning, to keep the engine running at a fairly fast idling speed, and to release the clutch lever very slowly and patiently until it has moved as far from the grip as it will go. If the engine stalls during the process try again with it running a little faster. This method will accustom the rider to the " feel " of the clutch and enable him with a little practice to make a smooth getaway every time.

Always learn to start away on a level surface until proficient.

Changing gear.

When well under way, and at about fifteen miles per hour on the level, free the clutch by gripping the clutch lever and at the same instant close the throttle slightly. Pause about a second and then with the right foot depress the gear pedal firmly and decisively as far as it will go keeping the pressure on the pedal. Release the clutch lever, smartly this time, at the same time opening the throttle again.

Take the foot off the gear pedal.

Repeat this gear changing process when the road speed has reached about twenty-five miles per hour, to engage third gear, and once more at about thirty-five miles per hour to change into top gear.

Do not look down when changing gear, but keep the head up and look well ahead.

To change to a lower gear the procedure is similar, but instead of closing the throttle on disengaging the clutch it should be left open, or perhaps only closed a very little, and the gear pedal moved upward firmly and quickly with no pause

Always keep the foot well clear of the control pedal when not actually changing gear, as unless it is allowed to return freely to its normal central position the next gear cannot be engaged. Note also that good gear-changing depends upon the pedal being operated firmly, and to the limit of its travel at each change. It must not be kicked. It is very bad practice to take the foot off the footrest and to operate the gear control with the heel, it can also be dangerous to do so.

The road speeds are quoted for guidance only for learners and do not represent the maxima that can be obtained in the indirect gears. Skilled riders will normally attain higher speeds and it must be re membered that special conditions will demand special treatment. For instance starting on a rising gradient will call for a larger throttle opening to get away, and a higher road speed will have to be reached before changing up. Some speed is always lost during a change of gear, and a change made too early will not allow enough momentum for the engine to accelerate the machine smoothly afterwards.

Stopping.

It has been said that this is more important than learning to start, and it is quite a good plan for a novice to get a friend who has already learnt (and who has passed his test on motor-cycles) to accompany him and take the machine to the top of a gentle slope. A deserted lane is preferable. The learner can then coast downhill and become used to operating the brakes, and if the teacher rides on the pillion the machine can be returned by him to the top for another attempt.

In normal riding the machine is stopped by closing the throttle and when the speed is down to about fifteen miles an hour disengaging the clutch. The gear control pedal is then, raised and released twice in succession to engage second gear and then raised slowly and half-way only until the pawl is felt to engage in the neutral notch.

Apply both brakes and release the clutch lever gradually making certain that neutral has been selected before releasing it fully. When the machine is stationary the engine can be stopped if necessary by raising the exhaust lifter lever, and if the journey is ended the fuel turned off.

When pausing at traffic signals, or when brought to a halt in traffic, do not keep the clutch held disengaged with the lever raised and the gears engaged.

If the stop is likely to be of more than a few seconds' duration always select neutral and re-engage the clutch.