Mercury 90HP 2 stroke compression on 12 yo engine

[NikTheGeek]

Just done my first compression test in years and got 8bar (116psi) on each cylinder. There was no noticable variation at all between the 3 which I thought was excellent on a 12 year old engine, however, I don't know what the compression should be as I can't find the info in the workshop manual. Anyone know?

Having said that, the compression tester is a Draper one and not a proffessionally calibrated one, so there's nothing to say it's spot on accurate anyway. 120PSI rings a bell, but anyone know for sure?

tnx

Nick

[_Ed_]

The actual reading is really irrelevant. What is important is they are all the same. Reason for that is they never all wear or fail at the same time, so one will go out against the others. just FYI compression test should be done with throttle open full, 2 strokes doesn't make so much difference but on a 4 stroke can be a huge difference in readings.

p.s. 12 years is young! The 'newest' engine I have I think is 1992?!! and the EFI on the fletcher is 1988 They all compression test just fine!

[Ianfs]

I'm no expert on this sort of thing, but what Ed has said agrees with the Mercruiser Manual for my V6 which doesnt give a PSI rating but a differential between the cylinders. If the differential is above a certain amount then it suggests it needs looking at.
I would therefore guess that it's the same for all engines.
Ed that's a good tip about opening the throttle fully, the book didn't give that info. I'll have to try that this Winter, before she is put up for sale. Cheers.