Undercut trans not shifting well

candieandy · March 22, 2010, 08:51:23 PM

hello all, well i took the bike out for the first time tonight. and it ran great, but didnt shift good. i recently had the transmission undercut to fix 2nd gear. the shop( fast by gast- great shop) also undercut 3rd gear. the shift forks and drum are new. it shifts hard by only holding the clutch and rocking the bike back and forth when, the bike isn't running. when its running, it shifts fine from 1st to 2nd, but won't shift to 3rd and so forth. the only other thing that i can think of is the clutch. i doubled up on the springs in the clutch. maybe its not letting the transmission dogs back off enough to shift between. gears. the last thing is that it seem to shift fine before i bolted the clutch back in. does anyone have any suggestions. im going to call fast by gast tommorrow to see what they say, but im lending a thought for my fellow fjers.

fj1289 · March 22, 2010, 09:37:43 PM

Does it shift into third at all? Fourth? Fifth?

How well did it shift through the gears while it was on the bench when you reassembled it? Trying to get all the bearing locating pins, shift forks and the gears themselves all lined up and not disturbing the crankshaft all at the same time is a three dimensional puzzle! Always seems to take me a couple tries to get it right. It should shift nice and easy when you've got it together. If not, something didn't line up right.

Also, try taking the chain off the countershaft sprocket and see how it shifts (turning the countershaft sprocket by hand between shifts) -- ENGINE NOT RUNNING OF COURSE!!! It should shift very smoothly and easily.

IF that checks out OK, try riding it in 2nd gear up to 5 or 6K, preload the shifter with your foot, and roll off the throttle - it should shift into third as the transmission unloads (clutchless shift). If it shifts OK like that, then I'd suspect your clutch as you suggested.

candieandy · March 22, 2010, 09:41:37 PM

i got it to shift once tonight into 3rd gear while riding. and i do believe it was at a higher rpm. not running it will shift into 3rd 4th and 5th,

fj1289 · March 22, 2010, 10:32:58 PM

Have you tried going back to just one clutch spring yet?

Troubleshooting over the internet is always a challenge, but seems to be like something binding slightly in the shift mechanism - or possibly the transmission. Clutch drag is a possibility - wondering on how you got it to shift into 3rd tonight to see if the clutch may be a factor.

How did you get it to shift into 3rd?

What did you mean by "it shifts hard by only holding the clutch and rocking the bike back and forth when, the bike isn't running. " in your first post? Does "hard" that mean it WILL shift into 3rd, 4th, and 5th but only with a lot of pressure on the shifter? Or by "hard" do you mean it "slams" into gear?

racerrad8 · March 22, 2010, 10:46:39 PM

Like FJ1289 has suggested, the bike will shift without the clutch being disengaged. On the up-shift you have to let off of the throttle to "unload" the drive cogs (the ones they undercut) and allow them to disengage from the gear they are driving; then it will up-shift. To downshift without the clutch, you must "blip" the throttle to unload the cogs while the bike in decelerating.

The clutch and trans are connected but two different things and as long as the clutch is engaged the transmission can be shifted.

In our racecars we do not use the clutch for anything other than starting or stopping. We have found that if the clutch is used during shifting, the weight of the car will cause the clutch basket to break and explode.

If it won't shift without using the clutch something is wrong within the transmission assembly/shimming, the shift fork and/or shift barrel. If it shift fine, then the clutch is dragging for some reason. You might have to go back and make sure you assemble the clutch assembly right starting with the washer behind the oil pump drive gear.

Randy - RPM

racerman_27410 · March 22, 2010, 10:47:06 PM

Quote from: fj1289 on March 22, 2010, 10:32:58 PM
Have you tried going back to just one clutch spring yet?

Troubleshooting over the internet is always a challenge, but seems to be like something binding slightly in the shift mechanism - or possibly the transmission. Clutch drag is a possibility - wondering on how you got it to shift into 3rd tonight to see if the clutch may be a factor.

How did you get it to shift into 3rd?

What did you mean by "it shifts hard by only holding the clutch and rocking the bike back and forth when, the bike isn't running. " in your first post? Does "hard" that mean it WILL shift into 3rd, 4th, and 5th but only with a lot of pressure on the shifter? Or by "hard" do you mean it "slams" into gear?

if it will shift thru the gears on the bench (turning the c/s sprocket by hand) then the transmission should be ok...... will the clutch disengage so you can find nuetral with the bike running?

andyb · March 23, 2010, 12:34:28 AM

Sounds a little like a draggy clutch from what you describe. Because you had the stuff all apart, give the clutch system a quick bleed and see if that helps.

If it's not going over 2nd for any reason, you've got something assembled wrong probably.

FeralJuggernaut · March 23, 2010, 01:23:35 AM

I like the bleed the clutch idea. how long was the bike down? did you pre-soak the fibers before loading them back in under the new spring? Did you change from dino to synthetic oil? Is there enough oil in it? I know that when it is oil change time, shifting goes wonky for me. Not likely your issue, but since you asked!

Opinion worth exactly what you paid for it! Good luck and let us know what you find out. Start with the simple stuff as Frank likes to remind us.

candieandy · March 23, 2010, 10:49:38 AM

thanks for all the tips guys. i will let you know what happens.

candieandy · March 23, 2010, 11:07:57 PM

well i checkled the clutch tonight.i completely removed the clutch and it still shifts hard. looks like im pulling thE motor again and there goes 4 qts of royal purple oil. dang

racerman_27410 · March 24, 2010, 12:14:23 AM

Quote from: candieandy on March 23, 2010, 11:07:57 PM
well i checkled the clutch tonight.i completely removed the clutch and it still shifts hard. looks like im pulling thE motor again and there goes 4 qts of royal purple oil. dang

know the number two gear can go on the shaft two ways..... one way works and one way doesnt.. DAMHIK

Frank

simi_ed · March 24, 2010, 04:13:46 AM

Hey, wait a minute. Don't waste perfectly good oil (even if it;s not Amsoil

). If the oil pan is clean on the bottom/exterior, just clan out your drainpan, then catch & reuse the oil. Of course, if you need some Amsoil ...<amsoil_simi@dslextreme.com)

candieandy · March 24, 2010, 10:41:17 PM

lol i figured out the problem. the # 2 shift fork was indeed on backwards. damn that is annoying. also i can pull the motor out of my bike and have the cases split in two hours im proud. thanks again for the comments everyone

racerman_27410 · March 24, 2010, 10:44:25 PM

good onya fer figuring it out.

there is a certain pleasure in being able to work on your own motorcycle

fj1289 · March 25, 2010, 02:12:40 AM

Good job on troubleshooting and fixing it!

Thanks for getting back with everyone on what the fix was too. We don't always get to hear "the rest of the story".

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Undercut trans not shifting well