only one worn rocker

iridius · New Member Joined: Oct 20, 2009 Posts: 2

The engine of my old 650 started making a knocking sound from the upper right side. I took the top end off and figured out that cause of the sound was a slightly worn cam lobe and a very badly worn valve rocker. The only wear I saw was on the lobe and rocker for the right exhaust valve. All the other 3 rockers and cam lobes looked perfect. All four valves and look the same and all the oil passages were clean. The pivot for the right side exhaust valve rocker was smooth as the other three.
So my question is this: What caused just one cam lobe and rocker to wear so badly? Any ideas on what would just one rocker to wear?

xsjohn · Posted: October 20, 2009, 7:29 pm Post subject: Re: only one worn rocker

Could check oil pump..........set side clearance to .002 thousands ........there is a recent post of mine on that subject......check oil passage to that side from the oil riser tube .......and the right cylinder runs a bunch hotter than the left .........at some point something has to give..........I would think the right exhaust area is the highest temp location on the engine.......what year bike........

Use an oil that is high in zink...........the only two I know of since the reduced the Zink in oils is Rotella Diesel 15/40 (or a diesel oil) and Valvoline VR1....20/50........I use one quart of each............

xsjohn

iridius · New Member Joined: Oct 20, 2009 Posts: 2

Thanks for these suggestions. The engine is a 1975. About 2000 miles ago, I had the cylinders bored 1st over and I replaced the pistons and rings to match. The oil supply tube is open in both sides. I will check the oil pump and try to locate the oil you suggest.

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