MidStar07 wrote:
Thought I'd bump this thread up and see if some wisdom can be gained.

In the last week I've ridden quite a bit and done a few things that seemed to help a little, but by no means did anything eliminate the racket. One, while riding through town with my wife I reached down and turned my PMS out about 1/2 turn (not sure where it's at exactly now, but not important), and I sorta kinda think it quieted the knock/ping a little. Tried a tank of MidGrade, which seems to have had no effect whatsoever. Change my oil to Mobil 1 V-Twin 20/50, and that seems to have had no effect whatsoever, either. (I was running Mobil 1 15/50 synth.)

Here's the thing: this noise is unlike any other noise I've dealt with in the past 40 years of riding motorcycles, because it ONLY happens between about 1/16th throttle and 1/8th throttle. This leads me to believe that it's not valve train noise, since that would be happening all the time. And it's not a case where lack of octane is causing the ping, since that would get progressively worse the more throttle you rolled in. This is the point that I'm not sure I've been able to make here to the knowledgeable guys like Doc, Musky, Gram, et al,: If I'm going up a hill at about 1/4 throttle in say, 3rd gear, the motor sounds awesome...no problem. It's at the top of that hill, when I roll the throttle back into the 1/16th - 1/8th zone that my motor gets LOUD again.

I tried explaining this last year, but I'm not sure if I ever made this point exactly, that I can be chugging or revving up a hill and all is wonderful until I roll the throttle back down into that "Zone."

What this also means to me is that no explanation to date is accurate. Yamaha says that the big engine parts need good oil to keep 'em quiet. OK, so why are they quiet under a good load? Doc, you've said that if the valves are noisy when it's hot, they need adjustment. But wouldn't they be loud at all throttle settings?

I'm wondering if perhaps the TPS causes the timing to advance too far in this throttle zone?

I gotta get moving today, but I will post more later. Anyone with any ideas, please chime in!

Thanks,

MS07

Sounds like it may be something to do with drive train noise. Transmission, transfer case, main drive. The reason I say this is because you say it only happens around 1/6 to 1/8 throttle and it happens at the top of a hill as an example. This would seem to indicate that it is torque related. Under higher torque loads, the noise is not there, but when you come over the top of a hill and roll the throttle back, your torque load decreases and you hear the noise. Think of it as gearing transitioning from positive torque (under load) to negative torque (under no load like coasting or very low throttle input). If there is any gear lash in the drive train anywhere, it may be creating this noise in that small margin area where the drive train transitions from positive torque to negative torque. Like in the area where the gearing is just kind of floating with each other, no coasting, no power load. Could be a transfer case chain slapping, excessive gear lash in the tranny, or something wrong with the final drive pulley or shaft bearings. In regard to the temp, this noise may not be apparent at lower temps because the oil is holding it's viscosity better. Higher temps will lower the viscosity of oil, some oils worse than others which could allow metal to metal contact between the gearing and result in the noise. I am reaching here, but something to consider.

EDIT: I just read your post stating it was in the top end, which makes my above lengthy paragraph useless. How is your rocker bushings?