125-200cc Crank & Case Advice

Finally got around to spitting the cases on a an old bottom end I picked up as a spare a few years back. I believe it to be a 2000-2001 CR125.
Was great to find it has the wider ratio gearbox in it (main shaft & 1st gear is 11T not 14T)
The plan is to fully rebuild it with a new rod & mains and use it in my 2004 CR165 but it looks like the main bearings may be an issue:

The RHS main bearing & casing has picked up. Was a good fit in the case, to remove it heated the case and tapped out the bearing with a suitably sized socket.



The LHS main came out of the case on the crank when split and it looks like it may have been turning in the case?


Any advice on how to go forward with this as I don't want to throw a load of money into new bearings, rod etc if its not going last?

Was thinking about having the cases machined and looking for oversized bearings, or having the cases sleeved?

Any advice would be greatly appreciated

Can you fit the trans internals to you 04 cases?

As the main bearing sits in a steel sleeve as long as there are no big burrs and the new bearing is a good fit I doubt if you would have any problems running those cases .

Dimple the steel sleeve in the case with auto center punch (all over) and use bearing retaining or cylindrical locktite on it

Loctite make a bearing liquid just for this. I can't recall the name, but I have used it several times over the years with excellent results and no failures. Check with the folks at Bearing Services or go to the Locktite web site.

Paw Paw

Thanks for the suggestions!

Have now sent the crank crank off to have a new rod pressed, new main bearings are here ready to go in and I have some Loctie 638 somewhere so I'll give it go

Loctite 601 bearing retaining compound

Maybe give the bearing seat a VERY LIGHT sand before application. Just to give remove any high spots & give the compound some more surface area to bond to. And I really do mean "Very Light"

& yes the older trasmission will work in the newer cases should the above mentions fail - I have done this exact mod