Crank Bearing fit

Should crank bearings be a press fit onto the crankshaft? If they slide on with a snug fit is that going to be an issue? I know if they are not tight in the cases they will spin and that turns into an issue. 

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Banana_oil
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5/2/2026 7:09am

I have noticed a difference between brands. My cr125s have press fit while yz have snug fit so probably normal. 

1
5/2/2026 11:48am

1996, 1997, 2000 Rm125s 

Nairb#70
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5/2/2026 1:34pm

1996, 1997, 2000 Rm125s 

Do those cases have steel press in inserts for the main brgs.?

The Shop

5/2/2026 2:17pm

1996, 1997, 2000 Rm125s 

Nairb#70 wrote:

Do those cases have steel press in inserts for the main brgs.?

I’m talking about the crank bearings around the OD of the crankshaft 

5/2/2026 5:53pm

1996, 1997, 2000 Rm125s 

Nairb#70 wrote:

Do those cases have steel press in inserts for the main brgs.?

I’m talking about the crank bearings around the OD of the crankshaft 

I think he's asking if the case's main bearing cavities have been sleeved, that's one solution if the bearings are spinning in the cases.

The bearings should be a "press fit", I normally put the bearings in the freezer, heat the cases and the bearing drop straight in, if they slide in at normal temperatures there is an issue.

3
Banana_oil
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5/2/2026 10:34pm
I think he's asking if the case's main bearing cavities have been sleeved, that's one solution if the bearings are spinning in the cases.The bearings should...

I think he's asking if the case's main bearing cavities have been sleeved, that's one solution if the bearings are spinning in the cases.

The bearings should be a "press fit", I normally put the bearings in the freezer, heat the cases and the bearing drop straight in, if they slide in at normal temperatures there is an issue.

Agree! I thought you meant on the crankshaft.

5/3/2026 5:48am

It should be a press fit usually I did my yz with parts at room temp and pulled the crank in with a puller

5/3/2026 6:41am
I think he's asking if the case's main bearing cavities have been sleeved, that's one solution if the bearings are spinning in the cases.The bearings should...

I think he's asking if the case's main bearing cavities have been sleeved, that's one solution if the bearings are spinning in the cases.

The bearings should be a "press fit", I normally put the bearings in the freezer, heat the cases and the bearing drop straight in, if they slide in at normal temperatures there is an issue.

Banana_oil wrote:

Agree! I thought you meant on the crankshaft.

I did mean on the crankshaft……not the cases. 

40acres
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5/4/2026 7:13am

I did mean on the crankshaft……not the cases. 

Yes, they are press fit using a crank puller on each side to install.

 

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