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Discussion Starter · #1 ·
I'm trying to tune my racebike, which is an 06 600. Last time I had it at the track, it was running so rich it was shooting flames out of the pipe. (I know, haga's R1 does it constantly, but I can't afford that much U4.) So i got it back and put it on the dyno. the graph was horrendous. Dips everywhere, only making 86 rwhp. So after exhaustive efforts, we've got everything smoothed out. the hp curve now looks way better than it did before. good smooth power all the way to 11,500 rpm. Then the power dies. it flat lines all the way to redline.

I've tried everything I know. Fuel pump is fine, all air intake/outtake checks out. I thought the timing might need to be adjusted, so the cams have been redegreed. That resulted in a major improvement, but it didn't solve the problem. TPS is good. the power commander has been mapped, re-mapped, and mapped some more. There is no difference between U4, 93, or 110 octane, or a blend of leaded/unleaded.

Honestly, I'm running out of ideas. mechanically, the bike is fine. It doesn't run bad (besides sputtering at low rpm before all the mapping, but with a A/F ratio of 11:1 thats to be expected), it just doesn't make any pk hp. I'll post the dynos when I get a chance. I'll take any input I can get at this point.
 

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There are a ton of possibilities, obviously, and I'll let you explore the easy ones. But if after everything you still can't find an answer, consider the possibility of weakened or broken valve springs allowing valve float at high rpm. I've personally experienced this... and it was NOT an easy problem to find. Bike ran fine 'till 10K (750), then it hit a wall like the rev limiter had kicked in (in fact - it felt so much like the rev limiter that I wasted alot of time chasing down an electrical/ecu problem that wasn't there).

But, I'd definitely troubleshoot the fuel & ignition systems first before even thinking about this.
 

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Discussion Starter · #3 ·
good call. I had the engine out of the frame and didn't think about valve float. i was also think that an ecu problem may not be so blatantly rpm dependant. did you have the 750 on the dyno? what's the graph look like? when i rode it, it didn't feel like a rev limiter; the bike ran, it was just reaallly slow. did it feel like the ignition cut?
 
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