Ciao crank bearings

I've been changing my ciao crank bearings before I fit my 65cc kit however twice now I've put the engine back together and the crank doesn't run freely as if there's some resistance between the crank and the casings ? I've froze the crank and heated bearings on both occasions and the washers are in place under the bearings so I'm confident they are seated properly on the crank. After my second attempt I have just watched another video where the guy says to make sure the correct bearings go on the correct sides . My question is are the bearings different and how do you tell which is which ? I can't see any differences or markings on the old bearings but there maybe some on the new ones but will obviously have to split the engine again to find out ... cheers again .. steve

Re: Ciao crank bearings

You may not need the same shims if you sre using an aftermarket crankshaft

Re: Ciao crank bearings

It's the original crank it's only the bearings I have changed

Re: Ciao crank bearings

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Re: Ciao crank bearings

where the bearings damaged when u took it apart the 2nd time? ru using a case gasket? lastly did u mod the intake and or crank lobes? sometimes even the slightest burr on the crank will make the crank lobe rub on the itntake patch. i think i ran a sharpie all over the lobe and whatched where it scraped off.

Re: Ciao crank bearings

Please post the exact bearing numbers as they are printed on the bearings.

Re: Ciao crank bearings

There was no damage to bearings As far as I could see I will have to strip again today to see if there are any markings on the bearings but they look exactly the same to me maybe just swapping them round will do the trick?

Re: Ciao crank bearings

Brandon Weiss (Detective brandon to you) /

If you did not heat the case when closing it to allow the bearings to seat into them in a resistance free manner, you probably "side-loaded" the crank bearings. This can be the source of your resistance, and will make the bearings short lived. (That is, if you installed the bearings on the crank first. If you installed them in the case first, you would need to heat the bearings when closing the cases to expand the inner race and allow the crank to slide right into them....same problem) Just speculation.

Re: Ciao crank bearings

Ye I heated the case first and put bearings on crank first is there a difference in bearing size between the bearing on ignition side of crank and the small case side? The cases are all bolted back together but the crank is not spinning as free as it should

Re: Ciao crank bearings

Brandon Weiss (Detective brandon to you) /

> Steve Davies Wrote:

> -------------------------------------------------------

> Ye I heated the case first and put bearings on crank first is there a

> difference in bearing size between the bearing on ignition side of crank

> and the small case side? The cases are all bolted back together but the

> crank is not spinning as free as it should

Did you put the bearings in the case, or on the crank first?

Re: Ciao crank bearings

Bearings went on crank first and heated the cases when fitted crank in

Re: Ciao crank bearings

Looking at the old bearings there is possibly a tiny difference in sizes hats to tell without a vernier to measure I'm just going to strip again and swap the bearings over will let u know how it goes

Re: Ciao crank bearings

The bearings are the same size one has the c3 tolerance. I’ve had the crank feel tight in the case before when it was installed. While the cases are hot after they are bolted together tap the small case half over where the bearing sits with a mallet it usually helps seat the bearing and allows the crank to spin free.

Re: Ciao crank bearings

So I've split engine again swapped the bearings over they did have the same numbers stamped on so assuming they was the same as each other but thought I'd swap them over anyway I also removed the oil seal during the fitting this time and put back in later.. it may have been the oil seal the bearings extra heating or just pure luck ! Either way the crank is now running nice and free so thanks to everyone who gave input ...

Cheers

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