Thanks Neil,
We're using the stock ignition, so timing is stock. We normally run in temperatures between 0 and -20C ( 32 to -04F), and the speeds are high, so we definitely don't have the heat you guys would. Obviously, we have to jet richer for the cold, I'm running a 205 main, DEG needle in the middle position on a 40.5mm Keihin carb. Not sure if this matters, depends who you talk to, but the exhaust duration is approximately 190 degrees. This engine runs the stock 72mm stroke, 86mm bore.
I agree with your comment on quality of gas. That was my impression as well, if he ran race gas, then there wasn't going to be a debate on things like jetting on race day. Last year, we ran a 50/50 mix with the same engine with the compression set at 150psi, without detonation issues. Also, does it make sense that with race gas you could run a little leaner yet still not create detonation or heat issues. I'm not sure how much a change in jet size from a 205 to a 200 would make in the fuel economy of this engine, but I worked it out last year and we were getting a little better than 10 miles/gallon with this engine!!! When you are burning 35 gallons of gas per six hour race (we race 4 events), the money difference of running premium to 50/50 to race gas is huge!!! But I really don't want to burn down an engine because I'm cheap with fuel.
We're using the stock ignition, so timing is stock. We normally run in temperatures between 0 and -20C ( 32 to -04F), and the speeds are high, so we definitely don't have the heat you guys would. Obviously, we have to jet richer for the cold, I'm running a 205 main, DEG needle in the middle position on a 40.5mm Keihin carb. Not sure if this matters, depends who you talk to, but the exhaust duration is approximately 190 degrees. This engine runs the stock 72mm stroke, 86mm bore.
I agree with your comment on quality of gas. That was my impression as well, if he ran race gas, then there wasn't going to be a debate on things like jetting on race day. Last year, we ran a 50/50 mix with the same engine with the compression set at 150psi, without detonation issues. Also, does it make sense that with race gas you could run a little leaner yet still not create detonation or heat issues. I'm not sure how much a change in jet size from a 205 to a 200 would make in the fuel economy of this engine, but I worked it out last year and we were getting a little better than 10 miles/gallon with this engine!!! When you are burning 35 gallons of gas per six hour race (we race 4 events), the money difference of running premium to 50/50 to race gas is huge!!! But I really don't want to burn down an engine because I'm cheap with fuel.
