Rebuild - Spacer required?

[Ken.Wallington]

I'm in the process of rebuilding the bottom end of the engine for my new trials bike. Can anyone recommend the best workshop manual for the 350cc singles?

I need to understand whether there is a spacer between the two bearing on the crankshaft drive side.

Thanks

[john.nash]

Is this clear enough ?

From the draganfly website

http://www.draganfly.co.uk/shop/pi17996 ... egoryId=82


The Waller Guide (on the AOMCC member's site) is pretty much the same as the workshop manual:

http://www.arielownersmcc.com/members ... terIII.PDF

[Ken.Wallington]

Yes it is, many thanks

[john.whiting]

You need three spacers on the drive side,one of.165in next to flywheel,one between ballbearings.285in,one between ballbearing and sprocket.586in.The genuine parts are of hard steel,but if missing,Ive made them out of mild steel bar,as they are all tightly held together by the drive spring and the only wearing face is the one against the sprocket,which should be hard if possible.Regards John.

[Ken.Wallington]

Thanks John, from the diagram the ones next to the flywheel and between the bearing are the same size, is that correct? I think I have them next to each other next to the flywheel. I'm learning....

[john.nash]

As John said, they are different sizes:

1446-35 Distance collar next to flywheel, .180" NH 1935-58
1447-36 Distance collar between bearings, .285" NH 1936-58

You also need shims on the timing side to get the play correct.

Here's the shock absorber (with spacer) which goes on the outside of the crank.:
1250-35 Spacer behind engine sprocket, .586" 1935-55

[john.whiting]

A slight discrepancy on the inner spacer,this dimension must be shimmed to centralize the flywheels,no matter what size is quoted .The between bearing spacer must be exact,say+or- .002 or the bearings will be endloaded by the spring,the outer spacer sets the chainline and is not so critical,say +or-,.020 is ok.Centralizing the flywheels is one of the important parts of assembling a single,otherwise the piston may be forced against one side of the cylinder.Then the end float can be set with shims.Sounds like a lot of trouble,and many people say "I cant be bothered with all that hassle".While the motor is apart is a good time to check your bigend for clearance and alignment,then you wont be plagued by excessive vibration.Regards John.