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Top 80 compression

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Just got timing setup  got TDC then turned the flywheel anticlockwise 090 on the dial gauge set the leading edge of the coil 14mm ahead of the leading magnet with a scribe not a felt tip pen

and when i pull it over its as if it is compressing twice ,i even doubled up on the base gasket thinking it could be that ,tried it with the plugcap off and gearbox off,no luck. Question could the magnet have any influence on this hard pull ,i welcome any thoughts ,i am considering letting Miniplane have a look at it I have run out things i can try.

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  • 5 months later...

First of all i guess you poured some oil into the cylinder and piston.

It is normal to have a nice compression after replacing piston and or cylinder.


Did you get the right size piston? They are marked A, B, C... Piston bigger than the right size coul lead to the problem you explained.


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