MOPED ARMY

retard your timing if you are pinging. check for a little melted spot on your piston.

okay, i think(having read your other posts) that you might not be pinging. pinging usually happens when you run high compression, but it could also be your timing. sure, your pipe should cause things to compress a little better, but i doubt it would cause any pre-ignition.

how pre-ignition or pinging usually happens is when things get too hot or too compressed and the fuel air mixture ignites before your piston reaches the proper spot. with a low compression head i doubt this could be happening.

try putting a little extra gas tank on, with high octane gas in it. run it for a while and see if that makes any difference. higher octane is less likely to pre-ignite.

Could it be engine noise resonating through the pipe? Steel tend to do this.

7 or an 8?? I thought it's supposed to be 5 or 6!

if you use octane booster be sure it 2t safe.Lucas octane booster in the red bottle is not