Hi, Could someone please tell me what the average engine compression should be for my 79 sporty. I have the Haynes and the HD manuals and I can't find it in either manual. Should it be hot or cold, wet or dry or a combination of some sort. I tried a search and it told me that a security something was invalid. Thanks in advance. Ride safe.

 

Engine compression should always be measured with a fully warmed up engine. The book says 120, with no more than 10% difference - i think most are higher. Mine are 155.

Check it dry. If the value is low do it again wet. If it goes up then the rings are not sealing. [The oil in there makes them seal better during the test].