Transmission Issue

[NYStunter636]

Bike: 05 636
Problem: Bike slips out of gear. Under power and sometimes on idle..

I know I'm not the first person with this problem. Do I have any options before I pull apart the transmission. Example, Ziptie the shift lever down.

I've been told its most likely the shift forks. Looked up how to replace them and it doesn't look difficult. Can I use the shift fork from another gear, 5-6 gear, in replacement of the one that is slipping, 1-2? They are the same. I'm never in 5-6 gear...Do I "need" all of the shift forks?

Just looking to make it through this weekend without getting randomly ejected.

[kawi636braaap]

Never rebuilt a bike transmission but I have done a few GM ones and Volkswagen before. I doubt you can reuse the shift forks on different speed gears because there most certainly different lengths. Im gonna say based on experiance its probably your syncronizers. Theres a brass blocker ring that constantly rides the taper of the speed gear and its the most likely part to wear in any constant mesh. When it wears slippage could result. Your absolutely sure its not your clutch slipping?

[StrictlyStunt]

Might be some help...
http://stuntride.com/vbstunt/showthread.php?t=39631&

I know there's another thread floating around here somewhere specific to the shifter forks.

[~03~raven]

If it just started you could try just changing the shift forks in hopes that your gears don't have rounded dogs yet. You can change those out with the motor still in the bike and without splitting the case just going through the oil pan.

But gears could be too far gone, so the shift forks alone won't fix that. Also you got to make sure you get the fork back in ride because if you don't it will slip worse and be hard to shift, or not shift. If you got the ability to just drop the motor and replace the forks, the bar guides, the shift cam, and the gears. That is what will fix it and if you can like that link above go get them undercut. If not everything will be ok but you never know when the other tranny might let loose.

[kirny]

Quote:

Originally Posted by kawi636braaap Never rebuilt a bike transmission but I have done a few GM ones and Volkswagen before. I doubt you can reuse the shift forks on different speed gears because there most certainly different lengths. Im gonna say based on experiance its probably your syncronizers. Theres a brass blocker ring that constantly rides the taper of the speed gear and its the most likely part to wear in any constant mesh. When it wears slippage could result. Your absolutely sure its not your clutch slipping?

you sir are dead wrong

[kirny]

no swapping the shift forks will not fix your issue fyi there are only 3 of them also if it is popping out of gear then you are beyond shift forks i only say this because i have seen other people INCLUDING ME tried to just change the forks and it didnt do shit so i took everything apart put it all back together just to take it apart and again.......anyways my suggestion to you is to get a used transmission and just swap out the shafts or get new gears and put them on your old shaft

[JohnnyP]

Quote:

Originally Posted by kirny no swapping the shift forks will not fix your issue fyi there are only 3 of them also if it is popping out of gear then you are beyond shift forks i only say this because i have seen other people INCLUDING ME tried to just change the forks and it didnt do shit so i took everything apart put it all back together just to take it apart and again.......anyways my suggestion to you is to get a used transmission and just swap out the shafts or get new gears and put them on your old shaft

100% correct the gear popping out means the engagement dogs and slots are already rounded...That is what causes the gear to pop out, every time it pops out they smack your shift forks. That is what bends your shift forks..So simply changing your shift forks will not solve the problem. The gear will start to pop out very soon after, and just bend the new shift forks also...

You need to split the engine cases and rebuild your trans, replacing the rounded gears and the bent shift forks...And if its really bad your shift drum also in some extreme cases.

[JohnnyP]

These are from the last 05/06 trans I rebuilt

This is your problem, notice the rounded edges that are supposed to be sharp

[kirny]

Even in those pics it's hard to tell the exct problem I have my old gets sitting in the garage and unless u know what ur looking at most people don't notice the rounding off

[JohnnyP]

Quote:

Originally Posted by kirny Even in those pics it's hard to tell the exct problem I have my old gets sitting in the garage and unless u know what ur looking at most people don't notice the rounding off

Its pretty clear to me, Id think anyone mechanically inclined enough to attempt a transmission rebuild should be able to spot the problem...If not here is a break down..

RED circled area = BAD
GREEN circled area = GOOD and what they should look