He has a 1986 Honda xr250r, he let me and my buddy ride it one year, an we deformed the cylinder till it was egg shaped. He sent it out to get fixed, they bored it 40 over, and finally it was round. Also he bought a new crank, and now he needs t get it out of the bearing, and the bearings out of the cases. We got the cases split, and the crank out of one bearing, but we would like to know if there is any "backyard" way of getting the crank and bearings out, without going to a mechanic or dealer.
My Father needs help.
- Thread starter mdavidso
- Start date
Ol'89r
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- Jan 27, 2000
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Heat the cases until you can sizzle a drop of water on them and they will expand enough for the bearing to drop out. You may have to use a drift and a hammer to nudge them a little bit. Use a large torch or heat them in an oven. If you use a torch, keep the torch moving at all times. Don't concentrate the flame on any one spot. Aluminum melts at a very low temp.
It would be a good idea to replace the main bearings if you are going to all of the trouble to replace the crank.
Reinstall the crank the same way by heating the cases first.
It would be a good idea to replace the main bearings if you are going to all of the trouble to replace the crank.
Reinstall the crank the same way by heating the cases first.
Ol'89r
LIFETIME SPONSOR
- Jan 27, 2000
- 6,958
- 45
Matt90GT said:
Make sure they heat the cases first. Simply pressing the old bearings out and the new ones in will wear the bearing bosses. After you do that a few times, the bearings won't stay in the bosses. If you heat the cases properly, you don't have to use a press. Also, make sure the machine shop is a motorcycle machine shop and not the average automotive machine shop or lawnmower shop. Check with your local dealer and ask who they use.
IMO, this is not as critical on most XR engines since the bearing bosses have a steel liner but, on all aluminum bearing bosses it is a must.