crank bearing trouble

Hey guys... just got my new OEM crank bearings for my rm250. I heated the cases till the were HOT and had the bearings in the freezer for a few hours. my problem was when i tried sweating them in they would go half way in then stop. So i pretty much beat the crap out of them to get them in all the way till they were about flush with the inner case. I didnt hit the inner race, just the outer one. do you guys think i damaged the bearings? they spin freely and dont bind up or anything. I just dont want to have problems down the road

If they spin freely you shouldn't have a problem. The problems arise when you press them in and they don't spin. I just took a guys RM250 apart that he pressed the bearing in and didn't check to make sure it spun. He was sure it was rusted by some mysterious water leak. I pressed out the bearing and it spun fine.

You should be good, even if you beat up both sides of the bearing you have about 1/2 inch of surface area that makes contact, It's screwing up the seals that causes the problems. Just make sure to do a vacuum check when you put it together.

how would i go about performing a vacuum check?

Go to the Thumpertalk Honda 2 stroke page. There is a sticky for making a leak checker for a 2 stroke. You can buy all the parts at Home Depot or Lowes for about 20 bucks. The sticky shows how to do it, but basically you plug the exhaust port. Remove the intake before or after the carb, connect an air pump and pressurize the case. Check over 15 minutes that the pressure does not decrease. It's a good way to know that you have put all the parts back in the correct spot.

Good luck. You should be fine.

You can buy leak testers but they cost about 200 bucks, I would suggest the Home Depot route. In theory you should do a leak test any time you take the bike apart. Air leaks will cause it to run lean. If you have the engine out to change the bearing it's really easy to do a leak test on the bench before you put the engine back in place.

ohhh you mean a leak down test haha sorry didnt really make the connection between the two. My dad has a tester i think so ill give it a shot. thanks man

Yeah, leak down/vacuum test. Just depends if you prefer to suck or blow....... Vacuum is sometimes easier because you can freeze a potential leak to see if the pressure change decreases, but most people don't have vacuum pumps laying around. Pressurizing the case is a whole lot easier. If your dad has the stuff you are set. One suggestion, next time use a press when you are putting your bearings in. It is a whole lot easier and you won't damage them. If you don't have one any machine shop should or you can buy a cheap one for $50 bucks.

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