I have a 2002 lowrider that I did a Head Quarters Dyna Sport package rebuild to. After one year I have just put on 10,000 miles since the rebuild. Just checked compression. I wish I would have done a compression test immediately after the build to have a point of comparison, but I didn't.

Both cylinders are at 220 psi exactly, then both are at 240 psi exactly after adding 1/2 oz oil. This build is rated as 11:1 compression.

My factory manual says anything above 90 psi is ok and if there is a significant jump in psi after adding oil it is an indication of worn rings.

Questions: Obviously my manual's specs are for a stock bike. Does 220 seem appropriate for 11:1 compression?

Also, assuming 220 is reasonable, is the 20 point jump to 240 psi significant or am I ok there?

Thanks for your opinions.

 

Adding oil will always raise the numbers some. Doing a leakdown test warm to hot engine to show what's really going on, but it sounds excellent to me. As for 11-1, don't know but you are up there. Not a lot of point on checking a new engine for leakdown or compression, since it's not seated . Once broke in is the best time to get the numbers.
Ron

 

Thanks rbabos. wouldn't 10k on the rebuild be considered broken in? 26K total on the bike.

 

I meant I would have checked it at about 1k for a baseline, so you missed it big time.
Ron

 

Your CCP will depend on static (11.0:1) compression and then the cam you are running. Earlier intake close, higher the CCP.

For a HQ build at 11.0:1 and a cam such as the HQ0039, your CCP is right in the ballpark.

 

Thanks Dalton. For a cam I have the HQ0033 (tornado) - gear.

 

Another question: forgive my ignorance, but what is the difference between CCP and PSI? What is CCP? I don't have it with me right now but I could swear my compression gauge measures PSI.

 

You are measuring cold cranking pressure in pounds per square inch.

 

Thanks very much.

 

What kind of gas do you have available in your area??
Scott