Yz250 transmission bearing not in completely

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2/23/2020 4:35 PM

A couple weeks back I posted about cracking my case installing a transmission bearing. Well a very reputable shop welded it back and installed the bearings for me and said it was good to go. I was looking at them and noticed the countershaft bearing was slightly higher on one side, as if it wasn’t completely in. Well I went ahead and put it together since he said it was good and everything was fine. The bearing holders went on, transmission went in good, it shifts fine, Bearing spun fine,no binding, but it’s just been in the back of my head that what if it’s not fine. I told him about it and he said if the bearing holders were able to go on, it doesn’t matter. Anybody had experience with something like this? What I’m thinking is, the tolerances are so close for lining up transmission shafts and bearings that if it were to not work, it would bind or not even go together. That could be my optimistic thinking.

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2/23/2020 7:25 PM

I would thing that after a couple of heat cycles the bearing will seat itself.

Paw Paw

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2/23/2020 7:29 PM

Paw Paw 271 wrote:

I would thing that after a couple of heat cycles the bearing will seat itself.

Paw Paw

Thanks for the reply. I am of course going to make sure I can’t hear or feel anything abnormal when I finish it. Which will hopefully be this week.

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2/25/2020 4:57 PM

Paw Paw 271 wrote:

I would thing that after a couple of heat cycles the bearing will seat itself.

Paw Paw

How hard should the front sprocket be to turn? I just put it on and it turns smoothly but it does require a little force. It definitely does not free spin (which I don’t think it should anyway). I can’t remember how hard it should be and I can’t see how much my tire rotates compared to before because I have all new drive components. And my old chain was a regular chain and this one is a big o ring chain.

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2/26/2020 6:06 AM

It should be obvious if it's binding. It should feel smooth with a bit of drag.

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2/26/2020 6:12 AM

Scrambled wrote:

It should be obvious if it's binding. It should feel smooth with a bit of drag.

It turns smooth with no drag feeling. Just feels like it’s harder to turn over than usual. I have a buddy who has a yz250 and we are gonna take his chain off today and see if there is much difference.

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2/28/2020 5:51 AM

It should be very easy to spin by hand without the chain fitted and in neutral.

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2/28/2020 6:01 AM

Scrambled wrote:

It should be very easy to spin by hand without the chain fitted and in neutral.

I’m going to take it back apart

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2/28/2020 7:47 PM

It will not spin, but should rotate smoothly . Remember that you have seal and gear drag on it even if in neutral.

Paw Paw

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2/28/2020 7:52 PM

Paw Paw 271 wrote:

It will not spin, but should rotate smoothly . Remember that you have seal and gear drag on it even if in neutral.

Paw Paw

I put the bike on its side overnight to see if it would leak oil after being welded and it dropped out about a cap full. Just tired of “rigging” it up. In search of a new one for a reasonable price. There is still a hair line crack that goes through the bore (where the seal sits) out into the outside of the case. If I could put a very very small amount of JB weld and I KNOW it would work, I would do it but I think no matter what oil is gonna find a way out. After taking the seal off to inspect the leak, I used a set of depth mics and mic’d the way the inner race of bearing sat on transmission shaft throughout rotation. No difference. Guess bearing was properly seated after all and it was just in my head.

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2/28/2020 8:05 PM

Paw Paw 271 wrote:

It will not spin, but should rotate smoothly . Remember that you have seal and gear drag on it even if in neutral.

Paw Paw

I found an 06 yz250 engine case. This will fit correct? It does not have the neutral switch thing but you just do without it and it is the same?

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2/28/2020 10:00 PM

Paw Paw 271 wrote:

It will not spin, but should rotate smoothly . Remember that you have seal and gear drag on it even if in neutral.

Paw Paw

Blackjack31 wrote:

I found an 06 yz250 engine case. This will fit correct? It does not have the neutral switch thing but you just do without it and it is the same?

I believe the center cases have been the same since 99. The kick start shaft and it's accompanying right side case were reduced in size in 02.

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