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BF15 Compression

hippovet

New member
I checked the compression on my new-to-me 2008 BF15D today. With a cold engine and full throttle, the top was 120psi and the bottom was 170. With a warm engine and full throttle, both cylinders were 180.

Looks good to me. Am I correct? Why such a big discrepancy between cold and warm top cylinder?

Thanks
 
When the engine is hot the bores and rings have oil present creating a better seal where as the bore is relatively dry in a cold engine. Being the top cylinder that is low, it may have scoring caused by an overheat. If it runs okay and doesn't use oil then leave it as is but I think you will find it uses oil.
 
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