Movs .60
 

Hi - I have a 60 with a really tight contra piston it won’t move when you back it off.I it’s not gummed but really tight.

Sorry movs

Damn spell check. Mvvs

MVVS 60 Diesel tight contra piston
 

Is this a Davis Head or a is it from MVVS? You might want to try a heat gun to warm the top section of the engine and see if you can get it to move.

Best, DennisT

tight contra fix.
 

I found always that MVVS and MPJet contras are too tight. You can get the contra out and spin it in a lathe and polish it down with oily 1000 grit paper to make them more of a sliding fit. Don't overdo this!!! On some engines it is easier to get the contra out from the liner by tapping it down the bore rather than out the top due to the bore being slightly tapered. Easier to refit the contra the same way.. PAW's see to have the right contra fit from new.

I ‘m just set it when it’s hot and leave it there and use heat to start it when it’s cold thank you for your reply