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By Peter D
#86703
Hello all, In the last couple of years I bought a 1961 500 Twin Sports. It was in boxes part from the engine which was in the frame. The engine had been restored which I verified with the firm that did it. To cut a long story short, I restored other parts and began to reassemble the bike. Gear box on, clutch fitted, primary case fitted and timing side assembled and fitted. I then went to turn the engine over. It was stiff to the point of impossible to turn over. I took the heads off, the cylinders and pistons. I poured some oil on the crankshaft bearing, and can now be turned over. the right hand piston was stuck in the cylinder, I lubricated that and it now slides up and down as does the left.

My question is, how should the crankshaft feel as it is turned over with the top of the engine off. Should there be resistance

I have a 2003 Indian bullet, and when I depress the decompressor, I can very easily turn the engine over. Much more easily than the twin.

The bike left Reading in 1961 and was exported to the USA. Some how it found it's way to Tasmania, Australia, where it lives now.

I'm hoping for some bright ideas, without dismantling the bottom of the engine.
By jack clegg
#86704
Crank should be free to rotate with no effort or resistance. It should always come to rest at TDC. A number of faults may be to blame. Strip it out & check everything. Do not trust the word of those who built it. They are biased. I suggest checking main bearings to see if they are C3 clearance (if you use CN standard bearings, the interference fit will tighten up the running clearance in the bearing). Also, crank may be misaligned, either from mismatched cases, or the timing side outer race not being assembled square in the cases. One test you could perform prior to stripping, heat the cases to 100 degrees, in an oven preferably or with a blowlamp on the crankcases. If the crank frees up when hot, this may indicate you have the wrong clearance bearings fitted.
I would also recommend you check the clearance on your pistons & bore too.
By Peter D
#86761
Thank You Jack, although I was hopeful, I expected a response like yours, so I have taken your advice and started to strip the engine. Thanks for you help, Peter D

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