compression readings

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knm
Posts: 6
Joined: Tue Apr 05, 2005 7:38 pm

compression readings

#1

Post by knm » Sun Mar 16, 2008 1:26 am

took compression readings on my pan rear was 62lbs. front was 65 lbs. is this normal good or bad . had one guy tell me it should be 90 to 100 lbs.



Jack_Hester
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#2

Post by Jack_Hester » Sun Mar 16, 2008 2:26 pm

Very low. Stock engine should be as the fellow said. 90 - 100#.

Jack

Cotten
Posts: 6911
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

#3

Post by Cotten » Sun Mar 16, 2008 3:10 pm

A cam with a lot of overlap will display low readings at kick speeds.

I would put airpressure upon each sparkplug hole at TDC and listen at the carb, pipes, and timing hole for unusual leakage. If there is none, and it doesn't use oil, I wouldn't fix it.

....Cotten

rickstone

low compression

#4

Post by rickstone » Tue Mar 25, 2008 3:13 pm

did you make sure the engine was warmed up good?
I get low readings when cold too.
more important that the two numbers are close together than high readings.
an old bike builder told me that kick starting to get compression readings is not very good indication of true compression. just too hard to get good readings when kicking. look for cylinder differences, and if close and bike has good power and is running good, don't worry too much

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