Originally posted by Top Gun 777
I would sugest to stay with #7 for most of the cases ( 6 for EFRA in Europe). Just worm up engine really good before you do your initial race tunning. His combustion chamber looks pretty good for me, Check the pipe, might be too short for that particular load.
Normally I would switch to a #7 when the temp goes above 25C (approx 80F) - do you think I should change to a #7 even at cooler temps? I have one still from the Winternats, I could try it out if you think it would help in this case?