Engine knock 2005 450 wr

Engine knock 2005 450 wr

at 3500 miles my 450 started knocking loud enough to be very annoying.

I have been around bikes for many years and under stand single cylinder rattle and clutch rattle, this is not what the noise is.

I have about 5500 miles on the bike now, I use it as a dual sport 40% road 60%dirt works great except for the annoying knock, noise has been about the same for the last 2000 miles.

I have the engine apart, piston ,rod and main bearing clearance are good, the engine looks perfect in side, all the bearings are good, what I did find is .002" runout on the drive side of the crank, yamaha's max runout spec, I have repaired cranks for forty years and always get them under .0005", but I sure the .002" runout on this crank is not causing the knock.

I checked the primary drive gears for backlash, I have from .001" to .008"runout/ in the .008" contact area, there is a noticeable knock when you rock the crank back and forth, .001" to .002" would be right for backlash on these gears, the clutch gear is not centered perfect, causing the runout, I sure this is causing the knocking noise. I have order new primary drive gears from a 450 in the 4wheeler, this clutch has torsional springs built into it, should work better for street riding, hoping the new gears have less runout. Has anyone found their 450 after some miles to start knocking and if so what did you find. This is not valves lash or cam chain noise. Any ideas would be appreciated.

What is the nature of the knock? By that, when do you hear it? What makes it quiet? Is load sensitive? Is it a full speed, half speed, or double speed knock (once every stroke, once every other, or twice per stroke)? A heavy thump, or a light rattle?

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