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What should the compression be on a newly rebuilt CB350 engine that is not broken in yet with tri ground valves? The CLYMER manual and my source says the compression for the stock engine should rise to the peak in about 5 to six kicks with the first kick about half of the compression and each subsequent kick adding half of the previous to the total with the throttle wide open. So say 80, 120, 140, 150, 155. This engine takes 15 kicks to get to 155 on both cylinders. The first time I did the right cylinder it got to 180 and the second time I did the left cylinder it got to 170. But on multiple subsequent attempts I could only get to 155 on both. Perhaps due to so much fuel in the cylinder from all the kicking diluting the oil and causing quicker leakage? I would get 30 on the first kick, 10 on the second and so on to 155. So the compression gets high enough eventually but it won't start.:confused:
 

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155 sounds fine to me, especially if the rings haven't seated yet. What's the manual say for a spec? Probably around 150-170 and less than 10 between the two. Make sure you're holding the throttle wide open and compression tests are best done after you run the bike and warm it up (if possible).
 

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The Clymer manual says 140 - 170 psi at sea level, so I am right in that range. It says up to a 25% difference in cylinders is OK or a change of 25% over time in identical conditions indicates a problem. So for my bike there is table that says one could be at 155 and the other as low as 116 psi.
 
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