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FIRELS1
09-29-2016, 02:04 PM
Any idea of where peak power is on a fl-250. Dg pipe, 9.5:1 compression, 34mm carb. ported head. Turing about 7800 now but feels like it's not getting on the pipe. I am thinking 8800-9000? Anyone have a dyno sheet of a modded fl-250? Thanks.

Mississippian
10-28-2016, 05:07 PM
Welcome to the FL250 forum. I don't have a dyno sheet, but your dead on for RPM's. When I was racing mine in the late 80's, I was getting high 10,000 RPM's.

What did you do for the head porting? I used to polish my exhaust port and rough up the intake. I also polished the dome of the cylinder head.

The idea of roughing the intake is to help atomize the fuel.

K-fab
10-31-2016, 06:15 PM
Any idea of where peak power is on a fl-250. Dg pipe, 9.5:1 compression, 34mm carb. ported head. Turing about 7800 now but feels like it's not getting on the pipe. I am thinking 8800-9000? Anyone have a dyno sheet of a modded fl-250? Thanks.
New engine build?
If it's a newly ported setup, the tuning will be different - plug chop time.

Ported head? Or polished dome and ported cylinder?

Was it running better at an earlier time?

What's your compression? Not the 9.5:1 ratio, but the actual compression pressure reading (you'll need a gauge).


Welcome to the FL250 forum. I don't have a dyno sheet, but your dead on for RPM's. When I was racing mine in the late 80's, I was getting high 10,000 RPM's.

What did you do for the head porting? I used to polish my exhaust port and rough up the intake. I also polished the dome of the cylinder head.

The idea of roughing the intake is to help atomize the fuel.We did the same thing with the jet ski engines - rough paper the intake and polish the exhaust port and header until they shined. Extrude-Hone was a great process back then. Polished the crank and the inside of the cases too.