I had the head shaved 5 or 6 years ago when I bored it to .060 and it ran fine from then until now so static compression ratio was only effected by boring it .020 (.5mm) which that shouldnt effect it much. But I got some high octane fuel today which i was gonna get some the other day but could only get the bigger jets because no one was at the airport, but anyways im gonna give that a try tomorrow. I did run it earlier today with .380 jets in it and it still is not flooding. That just dont seem right to me because I have 2 friends with banshee's and one is bored .020 over and dont know bore size on other but they are both ported with same exhaust as me and they are only running .340 main jets.

 

Well I rode the banshee today with some high octane fuel and the .380 jets and rode it pretty hard after i checked my plugs a few times and it didnt melt any electrodes off so I guess my problem is solved. Looks like I might need to jet it back down though and just run the high octane fuel my plugs were pretty wet after I eased it back to the house, and it is hesitating just a little when I hit the throttle but other than that everything is good. Thank you for your help everyone I appreciate it.

 

I hope it solved your problem Chevytech25.
If you have the cc of the combustion chamber and the gasket thickness, bore and stroke I could work out the actual compression that you are running.
Sometimes you are right on the edge with detonation. Just a little bit more and you drill a hole in your piston.
If you drill another hole let me know so I can learn and not go down that road again.

BTW: I re-read your post again and one thing I would do is look for a fuel restriction. Go from the tank to the carb. I burnt up a real good supercharged small block one time because it would not pull in high gear. The fuel line to the multi carb had a restriction from the factory. Melted the top land off of 5 heavy forged pistons in about 8 seconds.

If it feels lean on the top, back out of it and do a plug chop and see what it tells you.
Good luck.

 

Chevytech25,
glad to hear you got it running again. I have one piece of advice for you about fuel delivery for your carbs.. Get rid of the the stock petcock valve on your tank and replace it with a pingel valve. eleminate that tee fitting to the right carb. . Best bit of insurance I ever did for my Banshee... never have restricted fuel flow again...

 

sorry for renewing an old topic but for your future reference i think its called spark knock caused by low octane fuel and does burn holes in pistons just for future reference