Cranking compression test

[andrelouro88]

Hi,

I did a compression test on my bike and she gave me rear cylinder 195 psi, and front 197 psi from a 117 CI engine what is normally the compression on this engines?

Best Regards.

 

[Jersey Big Mike]

Hi,

I did a compression test on my bike and she gave me rear cylinder 195 psi, and front 197 psi from a 117 CI engine what is normally the compression on this engines?

Best Regards.

What work has been done to that engine? That seems high to me for a stock 117 in a BDM.

 

[andrelouro88]

I don't know i bought this bike in a auction i'm starting to work on her i had two bikes with this engine one is a 2004 version with the 117ci and had 125/124 in each cylinder, and then i tested my engine and it was 195/197psi that why i am asking this is to much of a difference.

 

[HMAN]

Sounds like there was engine work done? Not a bad thing ifn it was done right.

 

[andrelouro88]

I hope if that is true is a good thing if it was done right...

 

[Jersey Big Mike]

Well I always drop to the math.
Normal air pressure 14.7 psi Now and 10 times increase ie a 10:1 compression ratio would be in the 147psi

Based on that the bike in the original query is about 13:1 -- Damned high

 

[Jwooky]

@john sachs