when I get under high acceleration in say 2nd,3rd,4th, etc - I hear the engine start to 'ping' quite a bit.

It runs fine at lower speeds...

My dad is the original owner and Iknow we have never done anything to the motor - and I ride about once a month.

I noticed the pinging last time I went to pismo - and thought it might have been jetting.

Now it does the same at my local riding spot (prairie city).

Any quick ideas here guys? (I did change out the 'original' reeds - didn't seem to help)

Im in the middle of an ATC70 rebuild at the moment (4th gear went out - this one is gonna be fun, just love splitting the cases) - so I was hoping for some quick suggestions to try.

-Wayne

 

Maybe its building up carbon inside somewhere. Try a higher octane gas. Avoid octane booster if you can, I've scene it eat up all the gaskets in a sled engine before.