George,
Novels are a diesel unto themselves, there fuel requirements are a bit fussy, some will run ok on low ether fuels but most? wont and need the 40+ ether , I would run 25% oil at least a 50/50 castor olive should be ok. As you say they lose performance if run hot due to the high expansion of the alloy cylinder- the piston is low expansion high silicone / nickle plated. Andy W reported around 12,000RPM on a cox 8x4 from memory.
Stewart