Question about motorbike gearchanging
 

I'm currently working on a bike engined car, Hayabusa engine if it makes a difference, and there's a problem with the gear linkage.

I have never driven either a motorcycle or a BEC, so have no experience of what to expect from the gear change system.

At the moment the engine appears to be in neutral (the neutral light is on) but the linkage seems to move through a surprising distance, and I can see that the gearchange shaft that enters the engine is moving with it.

Anyway, the question is about how the gearchange on a bike operates, is it the case that the engine needs to be running in order for 1st or 2nd to be easily selected? Also, does the lever move through an arc to select a gear, then move back and then forward again to select the next gear, or is gear selection entirely dependant on the absolute lever postion (if you see what I mean :) )?

hope this helps.....

most modern jap bikes have the 1 down 5 up set up, as in 1 click downwards to select first gear then 5 upward movements of the lever to go thru all gears,
yes, it is better for selecting the gear if the engine is running, tho first gear can be achieved whilst engine not running.

the lever actually is spring loaded so that each time a gear is selected the lever returns to its original position, so in fact the lever only moves within a very small down or upwards arc, also the gearbox is sequential & most modern bikes will happily accept clutcless up changes but needs a blip on the throttle & clutch for down changes ie... going from 6th to 5th.
tho this can be altered if a quickshifter is built into the system, (expensive).

i,m an ex semi pro bike racer, so hope my experience helps.
happy to help if i can.

cheers
andy

Thanks Andy, that's very helpful.

Just one more quick question- I know it's down for first, but as the original pedal isn't on the gearchange shaft, that doesn't tell me which direction the shaft needs to turn in (because I don't know whether the pedal went forward from the shaft or back).

i,ve never looked at a hayabusa bike up close & also don,t know which direction the lever is originally, but try this.

if you have the lever (if not then a pair of mole grips, don,t damage the splines on the shaft tho),
try the lever pointing to back of the engine, put down into first, then just try going up thru the gears, if they select ok then thats the way, if not, try it with the lever pointing forwards & try again,

it all depends on the original setup of the linkage, tho don,t worry too much as its easy to swap the lever position, in the racing "world" some riders liked to have the gear selection as 1 up & 5 down ( it means its easier to change gear when leaning right over in mid corner, as creates more ground clearance), but this is all done just by putting the lever either way on the shaft, no need to alter anything internal on the gearbox,
i hope this makes sense:eek: , its easier to explain with the engine in front of me/you.

basically you can,t get it wrong once you know the correct position of the lever.
if making up a linkage for a BEC then fabricate it so that the direction of change can be altered, either a pull or push on the gear shaft, even the driver of the car can decide which is preferred then, as in the cockpit of the car you can have gear stick going forward for changing up or vice versa.

i hope thats not as clear as mud? :o

andy

I think normally the lever goes forwards from the shaft, but I have never riden a Hyabusa.

Try this for size - pic on the right



As you trying to turn the gear selector, turn the output sprocke/flange by hand and you should feel it snick into gear, keep going in the same direction until you run out of gears.