1974 Norton 850 Commando Starting Problem


Motorcycle Classics tech expert Keith Fellenstein

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Q: After letting my 1974 Norton 850 Commando sit for around four years I began to fit some new parts and upgrades. Among them is a Yamaha 650 reed valve which has been installed on the breather hose which exits at the right rear area of the engine. The bike now seems harder to kick over than it did a few years ago. Could this be caused by the valve? I also replaced the oil seal on the left side of the crankcase which required the removal of the primary but it seems doubtful that this could be the cause of the starting problem. It is as if the bike has more compression than before. Thanks.

— Pete Morland/via email

A: The only way I can think that valve would make starting more difficult would be if it was installed backwards. Remove it and blow through the valve. One way will let air through and the other won’t. We’ll call the one that does the inlet. Install the inlet to the timing chest at the right rear of the engine.

4/11/2019 10:35:52 AM

Did you drain the sump? I also have a 1974 Norton Commando 850. I have had a Yamaha 650 PCV valve in it for about 5 years. No difference, the Commando is always hard to kick over. (Unless you put on an electric starter as I did last year.)

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