WD Motorcycle forum

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Nov 9, 2019 - 5:36PM

BSA M20 1942 piston height

Hi,
I am the new owner of the BSA M20. Please help.
I found a piston problem when repairing the engine. This is unusual, but the piston seems to be too low. At the top dead center, the piston is not in the same plane as the cylinder. Please can you measure the height of the piston? Many thanks.

Marcel

email (option): marcel.fekete@mpsa.com

Ian Wright

Nov 10, 2019 - 12:25AM

Re: BSA M20 1942 piston height

How far below the top of the cylinder is the piston?...If it's 9mm (.354") you may have an M21 piston fitted...Ian

email (option): ian@wright52.plus.com

Marcel Fekete

Nov 10, 2019 - 10:04PM

Re: BSA M20 1942 piston height

Thank you for your response. I measured 5, 42mm. In my opinion, this is not the standard BSA piston. It will be a modified piston from the car. Or something like that.

Many thanks Ian

email (option): marcel.fekete@mpsa.com