Cylinder compression

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Jul 19, 2022
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Hello all
Just purchased a 74 850 from the USA which to my amazement started with fresh fuel battery etc
Had been stored for 25yrs + but turned over on the kick start ok

I intend to do a full refurb but to get an idea od the engine health I want to test the compressions

Does anyone know what pressure in psi or bar I should expect?

Cheers
NigeB
 
I would say 125-150 psi on a stock 850 - it is more important that both cylinders are within roughly 10 psi of each other. Check it warm and hold it at wot while spinning the engine over
 
135 psi both cylinders '74 850 MK II

6 kicks WOT warm

 
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