Reply To: Petter A1 backfiring through exhaust.

[disco2]

Hi it’s Will I have just had a look and these are the numbers I can see. It’s a wico mag looks like 676B it could be a 5 not a 6 at the start but I can’t see it well enough to be certain. The engine is a Petter A1 3hp @ 1500rpm serial number 1522000. I had a look at the points opening times and it appears the points are opening with the piston a bottom mot top dead centre. If my understanding is correct they should be open just before tdc. So perhaps the mag has been off and re fitted half a turn out.
Thanks for your help and advice
Best wishes William