Two Stroke Motocross

Two Stroke Motocross Forum => Technical => Topic started by: stepupmx on May 20, 2011, 09:11:33 PM

Title: 08 YZ 250 popping out of gear
Post by: stepupmx on May 20, 2011, 09:11:33 PM

Has anyone had any problems with YZ 250's popping out of gear. I have replaced the shift forks, all the gears looked good and all clutch components have very little time.

Title: Re: 08 YZ 250 popping out of gear
Post by: Coop on May 21, 2011, 05:39:37 AM

Does it pop out in just one gear all the time or any gear?

My guess would be worn out dogs on the gear(s). It's not always the teeth that wear out on gears, but the dogs seem to wear faster on some bikes. This could be from improper shifting, bad oil, etc.

Title: Re: 08 YZ 250 popping out of gear
Post by: SachsGS on May 21, 2011, 06:40:34 AM

Like Coop said,examine very carefully the engagement dogs on the suspect gears and I think you'll find they are rounded off.Japanese gearboxes have cast gears and once the surface hardening is damaged they wear very rapidly.

Title: Re: 08 YZ 250 popping out of gear
Post by: stepupmx on May 21, 2011, 11:09:53 AM

It has been happening in 3rd. 1st and 2nd are fine and once it starts happening in 3rd I don't shift up I just let off and idle it back to the truck. Is there anything else that could cause this before I split the cases again? I change the oil every2-3 rides but ride in the sand a lot so Im sure the gearbox takes more abuse than normal. Thanks for the advise

Title: Re: 08 YZ 250 popping out of gear
Post by: SachsGS on May 21, 2011, 02:18:40 PM

Throw your bike on a stand and pull the clutch side cover and the entire clutch assy. off.This will allow you an unobstructed view of the shift selector mechanism.Get a friend to give you a hand and as you rotate the rear wheel shift the gearbox up and down paying very close attention to the shift mechanism and it's action.You may find the shift selector "star" is chipped in the third gear detent area or something else has gone haywire there. :D

Title: Re: 08 YZ 250 popping out of gear
Post by: stepupmx on May 21, 2011, 07:27:43 PM

Great, thanks I will give it a shot and thank you guys for the feedback

Title: Re: 08 YZ 250 popping out of gear
Post by: TotalNZ on May 21, 2011, 11:05:18 PM

Quote from: SachsGS on May 21, 2011, 02:18:40 PM

Throw your bike on a stand and pull the clutch side cover and the entire clutch assy. off.This will allow you an unobstructed view of the shift selector mechanism.Get a friend to give you a hand and as you rotate the rear wheel shift the gearbox up and down paying very close attention to the shift mechanism and it's action.You may find the shift selector "star" is chipped in the third gear detent area or something else has gone haywire there. :D

X2

Title: Re: 08 YZ 250 popping out of gear
Post by: Coop on May 22, 2011, 06:28:06 AM

Yes Sachs has good advice. If that doesn't reveal the problem, unfortunately your next choice then is to split the cases and look at the gears and dogs on the gears.