Help! Crankcase bearing holes oval shaped.

[dave125]

Hello everyone

I recently purchased a 2001 cr125r with a full top end rebuild and later found the main bearing holes in the crankcase were oval shaped. The engine is making a slight knocking sound but still goes like nothings wrong.

Should i still be riding it?

Without having to buy a new left and right side crankcase $$$ what would be the best way to fix this problem?

[Ixion]

Arggh. Shit. I would not suggest riding it .

How oval is oval? If it is not too bad, Loctite make a special version of their wonderful goop, especially for this purpose.

If it is too bad for that, you may be able to get a machine shop to bore the housings out to circular again, and insert some thin sleeves (Loctite will keep them in place)

[Paul in NZ]

Stop riding before you fuck it completely.

Yes - this is a big problem BUT I'll bet a sack full of drunken hampsters that this is not the only example of MX wizardry to suffer this and some enterprising sod will have found an answer. Here the internet is your friend.

The compond shit is definately a last resort - its OKish at stopping bearing outers from spinning but lets face it if Mr Hondas finest alloy couldnt stop it pounding itself to death what show has some goop got?

A competent engineer should be able to advise a cure although its devilishly difficult to maintain alinghnment (sp) Being a single its simpler of course.

However - being a race bike maybe new cases from the USA are a better bet?

[wbks]

That bike is old as hell. I had an '01 I sold a couple years ago. If they are anything like kx's I would just buy a new bike or try and find some parts from the wreckers because my casings were over $900 which is rediculous considering your actual bike is probably only worth $1200. When did you buy that bike?

[dave125]

I only got the bike a couple weeks ago, its my first bike.
I've rung just about every motorbike wreckers in the country and still cant find any second hand cases.
I mite just put some loctite in the oval holes, this should do the trick.

Cheers for all the help guys

[k14]

This is quite common for old cases in RS125's. Get a good machinist to put a set of brass bushes in there and that usually does the trick. Still doesn't change the fact that the cases are flogged and the only way to properly fix is with a new set of cases.

[wbks]

Do what k14 said if you don't want to sell and cant afford new casings. Putting loctite in it wont to shit. Its suposed to stop seat bolts and fairing bolts etc from coming loose, not major engine parts. Brass bushes sounds good.

[Paul in NZ]

Do what k14 said if you don't want to sell and cant afford new casings. Putting loctite in it wont to shit. Its suposed to stop seat bolts and fairing bolts etc from coming loose, not major engine parts. Brass bushes sounds good.

Gah! Loctite is a brand name of a whole RANGE of products... One of which will temporarily sort this out....

Look - FFS do a proper job - Take the bloody bearing specs to a proper bearing factor and find one that will fit the crank and is bigger OD than std - (the OD of the widest part of the oval) perhaps you can find a proper bearing that can sort the problem.

Alternatives are welding up the bearing recess and re machining?

Gluing the thing up and flogging it so some unsuspecting muppet is BAD karma and surely what you were bitching about?

[Pixie]

Loctite 660 Quick Metal Press Fit Repair

>Repairs worn shafts or housings
>Repairs worn keyways
>Permanent repair - Cured strength 2180 - 4350 psi

Or
Loctite 680 Very high strength - Cured strength nominal 4060 psi

[rudolph]

At work we would bore the hole over size and fit a steal sleeve but in most cases this will weaken the case, on a couple other old bikes witch had no fit left in the bearing housing we had the outside of the bearings hard chromed to build it up but I think this might not work on modern cage bearings.

[slimjim]

yea..as all have said...its only temp been a fix..and tig and reboring back to orginal is bloody unlikely to work for any length of time...gota find some replacement cases...

[oyster]

years ago we had a '96 RS125 with a sloppy main bearing. About 0.1 clearance I think from memory. This is the perfect amount for a Loctite film(the correct grade of course) to form and hold well. Over 2 years of racing we replaced the bearings at 1250Km (half crank life) and each time the Loctite film was happily still there doing it's job. The clearance never got worse and the bike was quick, 45hp / 200km/hr plus as they're meant to be.
Later owners sleeved the cases and had lots of trouble, seizing bearings (too tight?) I think now it has new cases and BTW is the NZ current No 2.

[Pixie]

years ago we had a '96 RS125 with a sloppy main bearing. About 0.1 clearance I think from memory. This is the perfect amount for a Loctite film(the correct grade of course) to form and hold well. Over 2 years of racing we replaced the bearings at 1250Km (half crank life) and each time the Loctite film was happily still there doing it's job. The clearance never got worse and the bike was quick, 45hp / 200km/hr plus as they're meant to be.
Later owners sleeved the cases and had lots of trouble, seizing bearings (too tight?) I think now it has new cases and BTW is the NZ current No 2.

These Loctite products and the like from other manufacturers,are often used in original production processes as they often result in a more durable assembly in mass production.