I am finally getting to fix this MC21 that I have had and ridden very little ,the bike has low compression,about 95psi,and the lower cycinder runs intermittently,my Question is if im going to do a top end rebuild ,should i go ahead and take the crank out and put new seals and bearings(providing the crank is good ) on it,and if so could I do all that with the motor in the bike or would it be easier to just take the motor out, I don't have an engine stand, also what order for engine disassembly is easiest ?thanks for any suggestions .

I just started this process yesterday. If you want to replace the main seals you pretty much have to split the case. I'm not sure if it can be done on the bike or not. The engine is pretty light and easy to get out, and you have to dissconnect or remove all the same stuff anyway. You should read all the related technical information on the this web site as well as http://www.dreamgate.ne.jp/NSR/ . The nuts that hold the cable plate for the power valve are reverse thread. Replacing the bearings pretty much has to be done by a shop becasue the crankshaft has to be broken.
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james
Its not how fast you go...Its how you go fast.
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