2008 YZ250 not shifting

chase383
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chase383
Edited Date/Time 7/13/2012 7:12am
While racing on the weekend, I noticed that my YZ250 would go into (what I would describe as...) a false neutral. It did it quite a few times during the moto. The next moto the shifter completely locked ( I am assuming in 3rd)

I have not had a chance to open it up and take a look yet... but was wondering if anyone else has had the same problem and might know what to look for...

My first and un-educated guess would be that I may have bent a shift fork.

I haven't raced this bike often, actually it has very few hours on it, so I was a bit surprised by this.

If anyone has any ideas/info, I would appreciate it...
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PicardsFacepalm 9/20/2010 3:55pm
9/20/2010 3:55pm
Sounds like a shift fork? What kind of oil are you running. Yamahas shift for shit with synthetic. I had to move from AmsOil full synthetic to Yamalube semi-synthetic. It made a world of difference.
chase383
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chase383 9/20/2010 5:25pm
9/20/2010 5:25pm
PicardsFacepalm wrote:
Sounds like a shift fork? What kind of oil are you running. Yamahas shift for shit with synthetic. I had to move from AmsOil full synthetic...
Sounds like a shift fork? What kind of oil are you running. Yamahas shift for shit with synthetic. I had to move from AmsOil full synthetic to Yamalube semi-synthetic. It made a world of difference.
I was running just regular 10W-30 for the first bit and then changed over to Bel-Ray Gear Saver SAE80W.
chase383
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chase383 9/21/2010 1:17pm
9/21/2010 1:17pm
Yikes, sounds pricey... I really hope that isn't what it is.... I will hose the bike off tonight hopefully get the covers off...
chase383
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chase383 10/18/2010 8:08am
10/18/2010 8:08am
Finally had some time to get the bike some what apart..
The shift drum seems to be completely locked in place. Would this mean badly bent shift forks?
Looks like I have to split the cases regardless, unless anyone has another idea..

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Snapper
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Snapper 10/19/2010 12:50pm
10/19/2010 12:50pm
Yep, that needs tearing down. You'll probabaly find a tooth off of a gear wedged underneath the shift drum or something. I'd say 4th gear let go, sorry to say!
526
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526 10/20/2010 6:13am
10/20/2010 6:13am
So then at Aztalan you may not have had me in one more lap ? like you told me Smile
chase383
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chase383 10/20/2010 8:46am
10/20/2010 8:46am
526 wrote:
So then at Aztalan you may not have had me in one more lap ? like you told me Smile
LOL.. Joe is that you?? Actually I was riding my 125 that race.. which has been a very reliable bike..
The 250 though, I only have about 6 hours on it and raced it twice and this happens.

Good to hear from a fellow "MXVET.com"!! Smile

526
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526 10/20/2010 10:53am
10/20/2010 10:53am
A 125 ?????? That doesn't boost my Confidence LOLOL
Moto Mofo
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Moto Mofo 10/21/2010 9:50pm
10/21/2010 9:50pm Edited Date/Time 10/21/2010 9:52pm
Pardon my ignorance, but for the life of me I can't figure out what pin you speak of.



I recently purchased an '08 with low hours, and it started having shifting issues the third time I rode it. Split the cases, found a broken 4th gear and gouged out shift drum where the broken pieces had been wedged between it and the case. Everything else looks fine, but now that the tranny/shift mechanism is reassembled it still won't shift correctly. Sometimes it runs up and down through the gears just fine, but sometimes it just can't make the jump to the next gear. I bought one of these things new back in '06, rode it for a couple years and never had any problems at all.
chase383
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chase383 11/6/2010 2:48pm
11/6/2010 2:48pm
For those that are interested..
The problem was the end spline (clutch side) on the main axle. A couple of the splines sheared off and became lodged in the shift drum therefore locking it in 3rd.
I'm guessing the main axle was defective.. luckily no other damage was done.
Thanks for your opinions guys..
wet paint
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wet paint 11/8/2010 1:12am
11/8/2010 1:12am
Moto Mofo wrote:
Pardon my ignorance, but for the life of me I can't figure out what pin you speak of. I recently purchased an '08 with low hours...
Pardon my ignorance, but for the life of me I can't figure out what pin you speak of.



I recently purchased an '08 with low hours, and it started having shifting issues the third time I rode it. Split the cases, found a broken 4th gear and gouged out shift drum where the broken pieces had been wedged between it and the case. Everything else looks fine, but now that the tranny/shift mechanism is reassembled it still won't shift correctly. Sometimes it runs up and down through the gears just fine, but sometimes it just can't make the jump to the next gear. I bought one of these things new back in '06, rode it for a couple years and never had any problems at all.
We had the same problem. It would go through all gears then not want to the next time .Turned out it was a small burr in the case where the shift fork went in. The shaft that the forks are pinned to slides in the case from left to right and visa versa when you shift . I got the burr out then took scoth bright and a flat screwdriver and cleaned all of them. It shifted better than ever before after that. It seems a lot of clutch fiber and trash ends up in there and can not get back out. Now when I split cases I always clean those holes with scotch bright. It makes a difference.
will lange 7/13/2012 4:21am
7/13/2012 4:21am
This happend to me.. Teath broke off and destroyed the oil pump too.. Cost £1600 to have repaired!
chase383
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chase383 7/13/2012 7:12am
7/13/2012 7:12am
will lange wrote:
This happend to me.. Teath broke off and destroyed the oil pump too.. Cost £1600 to have repaired!
It ended up being a defective main shaft... some bits off the end teeth broke away and did some damage.
Bought all new gears and main shaft and it has been fine ever since.

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