440EX breaking up @ 3/4 throttle

[85atc350x]

I'm having trouble with my 440ex breaking up at about 3/4 throttle. I bumped the main jet to a 175, and the pilot jet to a 148, and have the mixture screw 2 1/2 turns out. I run 110 octane fuel. I have a dg exhaust system, k&n air filter, web cam, 12.5:1 compression, and a ported head. I'm currently running it with the airbox lid off, And the stock # spark plug........Any Suggestions??????

[44oEX]

ok well first of all the pilot would be a 48 not a 148 ( I hope ) and I would go back down to a 42 you don't need a 48. as for the cutting out part Play with the needle clip position. one up or down I don't remember. if it makes it better but still not perfect go one more notch. if it's worst go the other way.

[85atc350x]

Yeah, I meant a 48 pilot. Thanks, I'll try playing with the needle.

[pead_24]

check the color of the spark plug?

[MIKE400EX]

Might also want to try a colder plug like a DPR9Z.