AberdeenBikers

My bike developed a fault today 1999 YZFR6. The gears are not selecting correctly and is sometimes taking two or three goes to select. Running into a roundabout not wanting to disengage gear pulled cluth in to ride the cluch and the gear was lost without touching the shifter. I have checked external bolts and no probs. any suggestions?

Cheers

KARLOS69 wrote:My bike developed a fault today 1999 YZFR6. The gears are not selecting correctly and is sometimes taking two or three goes to select. Running into a roundabout not wanting to disengage gear pulled cluth in to ride the cluch and the gear was lost without touching the shifter. I have checked external bolts and no probs. any suggestions?

Cheers

Could be a bent gear selector. Can be caused by violent use of the left foot. What happens is the selector gets bent whilst trying to push the cog across and subsequently won't push it far enough for future gear changes. Hence the gear doesn't properly engage and can slip out again unexpectedly. Unfortunately it'd mean a gearbox strip down to repair.

Matching the engine revs (ie a quick rev as the selector goes through the neutral point between gears) when changing down and changing smoothly are the best way to avoid the problem.

Found a picture on the web for you. Ignore all the pink text it's not relevant.



Look at the middle gear. Just to the right is a polished groove in which the gear selector fork fits. When you change gear, the selector fork pushes this middle gear left or right. You will see the dogs either side of it which engage into the adjacent gears. Thereby the selected gear rotates and drives the next drive shaft via another gear. Note that the middle gear rotates independently of the other gears on the shaft.

When you try to push the dogs into position and they aren't aligned (ie engine not running for example), if you push too hard (ie stamp on the gear lever) you can bend the selector fork (not shown in this picture).

Once bent, it won't push the dogs fully home and hence the gears can slip back out into the neutral position again (which is the position shown on this shaft), ie neither the right or left cogs are engaged.

The folllowing picture shows two gearshafts together (different engine but essentially the same process) and you can see the gear selector forks on the thin shafts sticking out from the left casing. This is a car engine. Motorcycle selector forks are much thinner and thus weaker.



Hope that helps.

Cheers Gazza I will have a fiddle and see how I get on.

Having had a nose on the internet what is the chance it is a problem with the detent spring? and what exactly is it?

best ask Zax if this is a similar problem to what he's had with his YZFR6.

Id try the detent spring first, it fixed mine and its a £2 part (if that), and an easy fit.

Got to be worth a try.

Here's a thread on YZFR6 selection problems. There is a couple of mentions of the detent spring by Muller666 and Suomy further down the page. It's certainly worth a try.

Good luck.

Got the new detent spring fitted today and it was a £1 part, thanks everyone for the advice. Didnt fit it myself as I am lazy . The interesting thing is that the first to second gear high rev gear change is a doddle now, I don't run the risk of breaking the gear selector by kicking it anymore. So if you have the same first to second gear change problem may be worth changing your spring anyway at that price.

Thanks again for the help folks.

Glad to hear you've got it sorted.