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G50 piston hitting head
Posted: Tue Sep 14, 2021 6:17 pm
by Scottsmith86
Can anybody help , my I have recently been putting my g50 engine together with parts that i have gathered over the years and the piston is hitting the head before it reaches top dead centre , have I got the wrong piston , does the piston need machining to the head ? Any help with this would be appreciated
Re: G50 piston hitting head
Posted: Tue Sep 14, 2021 6:21 pm
by Scottsmith86
Extra pictures
Re: G50 piston hitting head
Posted: Tue Sep 14, 2021 10:50 pm
by bjorn
Hi Scott,
From the photos it appears that the piston is of a short racing type, so that is not the problem. Nor should the head be machined. I would suggest that you (loosely) fit the cam chain box to the crankcase and cylinder head. If there is still a gap/gaps between the cylinder and head and/or between cylinder and crankcase, a (substantial) packing piece is required under the cylinder. If there is no gap, you have fitted a connecting rod that is too long. I use a G50 connecting rod on my G80CS race bike. This is 1/2" shorter than the standard G80CS rod. Could there be a (longer) G80CS rod in your engine?
Hope you manage to sort it out.
regards
Bjørn