only do that if it's humid. it was very humid here last sat. your best bet is leave timing and jetting alone and take a little fuel pressure out of it. when its hot there is less oxygen in the air to burn so you need less fuel. try a 1/4lb check plugs and mph. depending on how hot it is probably take a 1/2lb away.I'd probably leave the jetting as it is and sneak a degree of timing in it and see if it picks up.I put a degree in mine last Sat and it picked up a tenth.