Petter A backfiring

What is the best way to set up the timing on a petter a11
The petter I recently purchased lets out quite a loud back fire through
the carburettor every now and then and I am wondering if the timing is
out a little ? turning the magneto on the swivell adjuster has no efect
Any ideas
Thank you

Steve
Reply to
The wild eye
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Many and various possibilities. Either a blocked slow running jet giving weak mixture or a badly seated, or adjusted, inlet valve . Could just be that the fuel level in the float chamber is too low. My favourite would be that the things has been run off load for years and is thoroughly coked up. Then the odd bit of carbon breaks off and props the inlet valve open or perhaps that the inlet valve stem is coked and sometimes sticks. The impulse should trip at TDC which is when inlet and exhaust valves are rocking. hth Roland
Reply to
Roland Craven
Indeed it was a blocked slow running jet
I thought it was timing because previous to the backfire I had the magneto of to clean and adjust the points .
After opening the carb it looks like some previous owner has been inside with a hammer and chissel and mangled all the delicate soft jets .
Looks like a carb overhaul kit is needed
Steve
Reply to
The wild eye
Mangled jets or not, it sounds to me like the mag is firing on the exhaust stroke. Take it off & rotate the crank through one full revolution. Try it again.
Might be an engine speed mag though, in which case it would make no odds!
Regards,
Kim Siddorn
Reply to
Kim Siddorn
Oh!I thought they all did that! better have another look at my 30 Petter A's CJ
Reply to
Colin Jacobs

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