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I am rebuilding my 1971 CB350 K3. Motor is sitting on the bench and I just put the head cover on. I noticed when keeping my thumb over the spark plug holes I felt less compression on the right side than I did the left. So just to check I did a compression test. I got 35 on the right and 55 on the left. Granted there is no oil in there but should these be equal at this point? Any ideas would be helpful particularly ones that don't have me diving back into this top end.

Thanks in advance for your help.
 

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Are you confident that your valves are seating correctly? I'm not sure how accurate your readings could be knowing that there's no oil in the engine. I'd put some oil in it and spin her over somehow til you see oil in the top end. I could be wrong but that's what I'd do.
 

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Im sure you put lots of oil on the rings and cylinder walls and the rings were spaced correctly. Since its still on the bench I would take the cylinder head back off and do a leak test on the valves. This is not proof positive of a great valve seal but a leak will show up. Also check the head gasket you might have got a bad one in the kit. Did you check the cylinder head and cylinder for flatness before assembly? I know you dont want to take it back down but how will you find the problem if you dont. Valves set, head torqued and low compression problem somewhere.

I hope someone can help but these are my thoughts.

Bill
 

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What compression tester did you use? Have you verified it is accurate? Before taking the engine apart check the valve adjustment and cam timing.
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