[Public-List] atomic 4 compression test

Sandi & Mark Bisset sandimark at rogers.com
Sat Dec 1 08:27:35 PST 2012

We are currently rebuilding an old Atomic 4 and trying to determine a baseline for compression. We were testing the engine when it was cold, using a battery, and got results in the 100-110 range. Adding oil increased compression to 115-125ish. The plugs are fouling very quickly in regular useage (black soot, not oily) and the engine is running rough at times with significant vibration. It has been suggested that it needs a ring and/or valve job. But the compression seems to be in the specified range.
Any thoughts would be much appreciated. 
Mark Bisset

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