Case bearings dropping out easily!

[Kenneth S (222)]

Hi Guys,
I am rebuilding my CR250RZ motor, and when I stripped down the cases, all the bearings fell out without much trouble at all, including the crank bearings. They don't have any play in them when you slip them back in, but will just fall out with a tap on the other side. This doesn't seem right to me. Has anyone experienced this before?
Kenneth

[Davey Crocket]

If you can push all the brg's in and out by hand then I would be looking for another set of cases.....that red stuff is no good Kenneth.....are the engine mounting holes flogged out?.....you could locktite a couple if that's all that was wrong but all of them means it's had something go wrong big time.

[KTM47]

Its a Honda.

[Kenneth S (222)]

If you can push all the brg's in and out by hand then I would be looking for another set of cases.....that red stuff is no good Kenneth.....are the engine mounting holes flogged out?.....you could locktite a couple if that's all that was wrong but all of them means it's had something go wrong big time.

The engine mounting bolts at the bottom are well worn and there is a crack in the case next to one...

[GMC]

Odd that they should all be loose.
Perhaps the cases had been sandblasted at some stage?

[pancho]

 Loctite bearing mount?

[Kenneth S (222)]

Thanks for the comments guys. I have a better understanding now

[JIM77]

What's the best way to tighten up the tolerance on engine mount holes? I've read that they can be a major cause of vibration, any ideas for shimming them?

Was reading an article on Eddie Warren recently and Apparently he used to shim his engine mounts to reduce vibration, not sure how though.

[alexbrown64]

Hi fella's, Ive just run into the same problem with loose main bearings in the crank case on a 1983 yz125k.  The left hand main bearing can drop into position by hand with no heat and can be pulled out by hand again with no tapping or heat.  There is no freeplay once it is in.  Looks like something let go in there once upon a time... see pic below.....Bearings are new AllBallsRacing.  The ones that came out must be loose too as when i split the cases the bearings stayed on the crank.
What are my options?  Do you think green 620 loctite will be ok?  Or try new OEM bearings?  I want to get a lot of years out of the bike.. there is a decent set of cases on Ebay for $99 plus post.. would that be the best option?  Anyone else had a similar story and a solution.  Kenneth, did you come up with a solution for yours?
Cheers,
Alex

[Tomas]

You can get steel sleeves fitted to restore correct press fit for crank bearings. http://www.klemmvintage.com/mxblueprint.htm (scroll down)  this will be good enough for racing motor if you are going to race the bike. also you can try gooogle to find odd size bearings. honda has some. i find honda bearing for my RM125 that has its O/D just slightly bigger (4mm) than stock RM bearing. Had  cases machine to the right size an fitted it in. no steel sleeve needed. give it a go. it is also good to have spare set of cases. The spare set may need some work too. I have 3 sets but luckly only one needed machining. also i would go with SKF or similar bearings for your crankshaft and gearbox. all balls is ok but not sure who  make those bearings.

[Simo63]

On one of my YZ125D motors I had a machinist make up a jig to remove the original ring, manufacture and pressed in new metal rings so she's like a brand new motor.  Second hand 1977 cases are all as worn out as each other so this was a more permanent fix.

I can give you the guys contact details if you want.

[sleepy]

Best to machine it out and press fit a steel ring in place and then machine to size to give correct bearing fit. The loctite would only be a temp fix.

[sa63]

if its loose (on the way to being flogged out) how critical is determining the centre point for machining - what tolerance is acceptable? i take it the c3 bearings help with this?

[alexbrown64]

Tomas, the link you sent had some great ideas on case machining.  It is however, $130 US per side for machining and ring.  This is ok when you have a rare case or due to age they have all become like that as you wont get much change out of $400 AU for a pair including post both ways but it is still a great option.  Simo, can you give me the guys number... i suspect locally it cost more but i could ring him in the new year and discuss options.  I may go with a second set of cases just to have some spares.  Then keep the really worn ones to get machined in the future.  Sleepy, do you know anyone in OZ that does the machining and press fitting?  Here in WA, its over $100 an hour for most workshop jobs so it can become prohibitive unless it is really necessary.  I have all new bearings and seals for the bike which are all OEM (mostly Koyo), exept the mains which are AllBallsRacing but still have "Koyo, Japan" stamped on them.
Cheers,
Alex

[alexbrown64]

Sa, what are C3 bearings?
Cheers,
Alex