Ok, Who bought some of those used/ returned under warranty engine blocks from thatsdax for 25 bucks apiece? I bought 4 and am VERY pleased. So far I've pulled the heads on 3 of them to take a peak and don't see any wear/slop on connecting rod bearings or any piston scuffing or abnormal cylinder wear. Two of the engines already have gotten new rings and headgasket and put back together. I have already run one of the engines on a bike of mine and am very pleased. With new rings it fired up instantly and runs very smoothly. Power is a little low due to new rings not being fully seated yet and I haven't added my special brew to the gas to compensate for the high altitude induced excessively rich fuel mixture setting (6 oz per gallon of 15% radio control fuel...note don't do this at regular (low) altitude or you'll fry your engine from lean mixture....at my high altitude I need a smaller jet to compensate for the "thinner" air but this is a poor man's solution that works fine). rcjunkie PS: I kinda got carried away about octane and our engines. Higher octane typically won't help a well tuned running engine. However, ifyou are running your carb too lean or have excessive carbon buildup...higher octane would improve performance caused by these issues. Lean mixture can cause detonation and power loss....high octane would reduce chance of detonation/preignition. Carbon buildup on cylinder can increse compression ratio slightly but it often is a trigger for preignition and high octane can help prevent this. In either situation it is better to resolve the condition than to treat the symptom with high octane fuel.