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.
MC21 Rothmans
RS250
RC31
CRF250X
748R
Porsche (many)
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