I'm baaaaack!!!..... with a problem! By Gti (Read 601 times)

[Gti]

I recently purchased a +4mm crank from Scooter elements, and had my piston shaved, when trying to the case together yesterday, when i put the fastener in the case and tighten it up, the cr5ank will not spin freely. Why? This is perplexing and I am almost at my wits end with this project!!

Thanks in advance1

[jct842]

Get a hold of scooter elements, they know what they sell and are in the best position to help.

[Alleyoop]

With the +4 mm crank I think you need thicker gaskets to clear.
Alleyoop

[justbuggin]

pull it back apart dry fit the case together without the crank in it and measure the space between the main bearings and measure the space from outer edge of the crank bearings the case should be just a little bite bigger than the crank or it will pinch the bearings tight

[Gti]

just,
what if the the case is a bit smaller? what is the fix for that other than a new case?

[Alleyoop]

It is NOT the case, it is the LENGTH of the Crank Arm that is heading the HEAD and will not allow it to rotate. So depending on If the JUG is to short then a thicker gasket needs to be put between the JUG and the CASE so the PISTON on the CRANK DOES NOT go higher than the JUG and Hits the HEAD.
Alleyoop

[Gti]

I haven't even gotten as far as the head. If I get a chance tomorrow I will shoot a quick video. Alley if is one that I have learned from you and this experience is to check and double check as you go along. So at the pint I am at now is the engine is no further than putting the engine halves together. I check to make sure the engine and chain will spin free and the chin is not bound up. I can turn the engine to a point and when the crank arm would be at TDC the engine will not turn, the chain is still attached and all else seems fine.

[justbuggin]

if it is too tight then check to see if the bearings are pressed all the way on the crank and check if there is anything the crank is hitting on i would put the crank in one half of the case and rotate it to see it clears ok and then do the other side as well

[Gti]

I didn't try that but I put it together without the gasket and all that to see if it would still do it and it did. But if I get time tomorrow I will try to do each half to see. I thought the case was a bit dry to I coated everything with motor oil, was going to try some assembly lube to see if that would help.

[justbuggin]

some thing else you can try is to tap the crank side to side with the case together to seat the bearings into the case halves so they are not bounded up

[Alleyoop]

Before you put the CRANK in the case did you check if the CRANK ARM rotated on the Crank itself. Then also check to make sure the Counter Weights are NOT BINDING on the INSIDE OF THE CASE ITSELF. If all that is good then it has to be the BEARINGS.
Alleyoop