BQUICK
05-28-2018, 08:57 AM
A buddy has a decomputerized 1989 Yamaha Excel that has Hydrotech heads, modified horizontal intake with carbon fiber reeds, big carbs (jetted up to 172s). Only running 22deg timing. First time it melted a piston he had 87 octane in it so we figured that was the cause as Hydrotech says needs 93. Put it all back together and melted another piston. This time I had told him to run closer to 40-1 oil to be safe. Still blew.....
Only cause I can think of at this point is that one of the fuel pumps is weak causing a severe lean condition at 5000 rpm+.
Any thoughts?
BTW this is on a Hydrostream HST (82 mph with 28 chopper)
Only cause I can think of at this point is that one of the fuel pumps is weak causing a severe lean condition at 5000 rpm+.
Any thoughts?
BTW this is on a Hydrostream HST (82 mph with 28 chopper)