G
glenwill
Guest
One possibility is that you might not have had the vacuum port (to the petcock) plugged when you did your first check, and it was able to suck enough air to give you a better compression reading.
I don't think that the vacuum port will give it enough air to get a full, PROPER reading, but that is one possible reason for the higher reading.
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Hmmm...yes, that's a definite possibility. I did plug it when I was adjusting the air screws, but I don't remember whether I had it in when I did the first compression test. Thanks for thinking of that.
What about the numbers? My Clymer manual says that compression should be 128+, and that less than 92 means it needs a rebuild. I am well above the rebuild threshold, but 2 cylinders are below the minimum of 128. Is this a concern?