Help CRF Style pit bike transmission issue

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Dudewith4x4

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Last week I bought a "Sikk MX" crf style bike and just added a stator and a few other minor things to get it running. I took it for a test ride today and noticed it seems to be slipping in 2nd gear or something. When I put it in 2nd it seems to take off fine but then starts jerking and catching like crazy. All the other gears it seems to be fine in though. So am I screwed or is there a simple fix? Its a 125cc 4 speed manual if it matters. 1-n-2-3-4. Thanks for any help.
 
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Re: HELP CRF Style pit bike tranny issue

Sounds like it could have a few teeth on the 2nd gear cog damaged, prob wouldn't hurt to pull the clutch side case off and check for metal shavings in the the sump plug strainer.
 
Hey thanks for the reply. I drained the oil and there was about 5 little shavings in the oil. I removed the case cover and there was nothing in the strainer?
 
it sounds like the motor needs splitting then, the broken off pieces will still be inside the 2x engine case halves....
 
****... Is there a tutorals on how to do this? I can get it as far as taking the head, cylinder, and piston off but as far as splitting the actually case im lost.
 
have you checked out the shift drum forks, are they worn?
or checked out the link i posted above?
 
Yeah I did and doesnt seem worn at all. Thanks for the linky btw.
 
Unrelated but I took it on about a thirty minute and ride and while skipping 2nd gear it did fine. After it warmed up though it seems to start spitting and sputtering and then I have to stop and after a few minutes I can start it and it will be fine. I need to repla e the plug but any other suggestions? I rebuilt the carb aswell.
 
otherwise check for vacuum leaks, tiny gaps can open up when an engine warms up.
start the bike, let it idle, now spray some degreaser/carby cleaner on all the joins between the carby and manifold, manifold and head, and the carby to fuel bowl.
if the idle changes in any way, then there is your leak.

when you rebuilt the carby, did you blow the jets out with compressed air?
did you remove the mixture screw, and clean out the air channels?


what carby, and what jetting is it running too?
 
My67xr- thanks for all the help and links man. I really appreciate it. I found my problem in the running problem. The guy I got the bike from gave me a wrong woodruff key for the fly wheel and it had had some issues with timing because of it. I'm cleaning the carb again tomorrow and checking the valves again. I'll check the jets tomorrow aswell. Any idea what sizes they need? Also what notch should my needle be on?

Sorry to the mods if it's in the wrong spot. It was a mistake. No need to get but hurt about.. Are these bikes not welcome here? Would a build thread be unipropate?
 
Mate the drama is your bike isnt japanese from now on anything to do with this bike put it in the chinese mini section mate. By the way a good start with jetting for this sort of engine is 17.5 pilot jet and 95 main with the needle at the second bottom groove.
 
Thanks for the info man and sorry about the mix up. Bout to go take the carb apart.
 
Sorry it took so long for me to get back with you guys. its been a crazy couple of weeks. Anyway I cleaned my carb and I had the correct jets and it seems to be running better now. I took the bike apart again to figure out this tranny issue.

Heres a video on how it shifts... It doesnt seem right to me.. Any help would be awesome.


http://youtu.be/DoD4Dmyv1WY
 
when you rebuilt the carby, did you blow the jets out with compressed air?
Sometimes that does not even clear them out... especially the idle jets on smaller engines... i use the finest peice of wire i can find... its not good to do heaps to a jet but it works
 

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