Originally posted by markp27
Ok, first the technical details. I'm using Runner Time Top 16% fuel, a 6TF plug and 0.4mm of head shims. The motor is a Novamega 3P (#2106) which now houses the Palmaris internals.
Air temperature was 10C and very little humidity.
Mark, did you check the head clearance as per the method ziggy mentioned? Perhaps you need to shim down with 16% nitro ! I'm using 25% and with hot climate conditions here, we stick to 0.3 mm with the 7TF plug. What's the head clerance measurement on the JP FX? Perhaps try to follow that one.
Don't know if you read my previous post here but what I found out was my head clearance with the stock 0.3 mm shim was 0.8 mm on the NovaMax crankcase ! I think that's too much. JP FX crankcase may differ from your old SX12 NovaMega crankcase.
On the Gen 1 BRB, I took out the stock 0.3 mm shim and ran it as is without shims with 0.5 mm head clearance (approx 0.02"). Now for safety reasons, I run with just 1 copper shim (0.1 mm). I think that's the ideal head clearance with 25%.
I have not measured the head clearance on my BRB Gen 2 in the normal Novarossi NSR crankcase. Will try and post some numbers.
With 16%, I think it should be less than 0.5 mm head clearance. Try aiming for 0.4 mm head clearance. Measure it with the solder tip. You may require different number of shims to get to the head clearance you want.