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Discussion Starter #1
Not sure where to post this... but I have a thud-thud-thud rhythmic vibration feeling in my bars around 3000 RPM at 40-60 MPH in 6th gear. It also occurs in that speed range in 5th and 4th gear but less pronounced.

2003 GSXR 1000 with less than 8000 miles.

The thud-thud goes away between 70-130 (have not tried faster). It could be that it's still there, but the frequency is cancelling it out or something. The bike handles stops and goes just as you would expect. It might be in my head, but it feels like the thud in the bars feels more intense as the bike has come to full operating temperature. When I pull in the clutch at that speed it FEELS like it goes away or is dramatically reduced. When I rev to 3000 in neutral and hold it there, there is no vibration. Only when moving. When I feel on either side of the crank - stator or clutch, I don't feel any vibration or thud (when driving at that speed, reaching down to feel the cover to see if I felt it there...) I thought maybe the stator is binding on something... but I was super careful. I don't think it's that and I also feel like I would feel that through the stator cover. Before the "incident" described below, I don't recall ever feeling this same thud-thudd in the bars.

Background: I put her down on the lowside on the track. Busted the stator cover. No other damage apparent. There was some amount of dirt ingested near that stator area. I wiped it out and then rinsed it all down several times with diesel in a sprayer. Then I pulled the oil pan and cleaned it. The bottom end looked very clean from underneath. I installed everything back and it fired right up. I ran it for an hour and then put another batch of fresh oil and new filter on. I've now driven it about 1000 miles. It runs great.

Some of my wheel weights did fall off in that scuffle with the ground. I pulled both wheels and balanced both of them again, and taped the weights this time. Both wheels are balanced. It's not that...

It has pretty new tires. There are no flat spots or anything like that.

I have cleaned and lubed the chain I don't feel or see anything weird in that area.

If it was engine damage I would think it would manifest at all RPM range...

I'll check the front bearings by pulling back and forth on the wheel to see for play but when the wheel was on my balancing stand it spun very freely. I see no damage to the rotors or pads, and it has new pads from my last track day.

No idea what could be causing this. Any ideas where to start (other than checking front wheel bearing which again I would think would manifest at all speeds/RPM range.
 

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Discussion Starter #3
No I just had the calipers off when I balanced the front wheel and I ensured they are torqued to spec. I'll double check when I get home today.
 

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When you say 'thud', is it audible, or do you perceive it only through your hands? If audible, how loud is it, that is, how clearly can you hear it over the normal noise of wind and machine? When switching gears, does the thud follow engine speed, or rather vehicle speed?
 

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Check the steering head bearings for play. There are youtube videos showing how.

Tires can be bad from new. Take a close look at yours. Look for a bulge while spinning it. Check if there are any noises indicating that the wheel bearings are failing. Also look for a bent rotor but, as previously said, I'd expect there to be other symptoms that are noticeable at the brake lever.

I commented elsewhere about your generator cover.
 

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Discussion Starter #6
The thud is NOT audible at all. It's only felt, and mostly only through the hands.

It's subtle - but unmistakable.

It's most noticeable in very light loads, steady speed, or slightly decelerating. When I downshift into 3rd or 4th gear it decreases in intensity.

I didn't get to check wheel bearings last night but I will check them tonight along with the head play.
 

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Discussion Starter #7
Over the weekend I double checked everything on the front end. Calipers are tight, pads are very new and are slightly dragging on the rotors but nothing there. Rotors have no cracks and are straight.

The wheel bearings have no play that I am able to detect by pulling and pushing on the wheel.

Head bearings are fine. The steering is fine.

I pulled off the front sprocket cover and inspected the front sprocket. I cleaned everything in there. Everything is fine.

The one thing was a couple rollers on the chain were tighter than others but the chain is fine.

Symptoms are still there. Must be something in the motor.
 

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"Head bearings are fine. The steering is fine."

I continue to wonder about this. Did you have the bike supported such that the front wheel was off the ground and the steering was free to turn? To do so requires lifting the bike from underneath or lifting it by the frame sliders, if you have them.

Tight rollers aren't a good thing but I wouldn't expect it to produce a thud at the bars.
 

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The thuds are regular, like clockwork, right? Do they follow the engine/vehicle speed, getting faster as you go faster? How fast are they? If you switch, say, from 6th to 4th, will it be as fast at the same engine speed, or at the same vehicle speed.
 

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Discussion Starter #10
Yes like clockwork - if I change from 6th to 4th, it changes in intensity but doesn't seem to change in frequency. As the speed changes it fades away and it MIGHT be changing frequency but but I can't pick up on it, it just seems to change in intensity. At 80 mph for instance, its' still there but it is just a super faint feeling through the bars.

How I tested steering was - had bike on rear stand and then jacked up the front end (on the headers_) so fron wheen completely free. Of course the steering stabalizer was just there but I felt no restrictions or anything weird there, and pulled and pushed on the wheel to see about the bearing.

I did find something else over the weekend. When I barely have the front brakes applied and am crawling forward at a walking pace - I can feel a tiny wobble in the bar end. I think something must be tweaked... I'm going to loosen my triple tree and make sure the forks are not tweaked off. I guess there must be some sort of rotor to caliper influence if that is occurring. Still more testing to do on it. Maybe I'll put the stock pads back on for kicks as well. Maybe something got tweaked in my lowside
 

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Yes like clockwork - if I change from 6th to 4th, it changes in intensity but doesn't seem to change in frequency. As the speed changes it fades away and it MIGHT be changing frequency but but I can't pick up on it, it just seems to change in intensity. At 80 mph for instance, its' still there but it is just a super faint feeling through the bars.
If the thud is there in the same vehicle speed range, regardless of engine speed, so that say going 60mph and shifting from 6th to 4th doesn't change its frequency appreciably, then it would seem to be related to the chassis, so you would be in the right direction, looking at the steering and wheels. On the other hand, if that is the case, I can't see why it would be there only in certain gears and why it would change in intensity when shifting gears, since that strictly concerns the engine. Given all the data so far, I would consider the drive chain as a likely candidate, but that would certainly make itself felt through the footpegs first , even if it did make it to the bars, and you don't mention that. Also, it wouldn't be entirely even, but still, perhaps checking its tension and overall condition wouldn't be a total waste of time.
 

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I use the same socket as the axle nut on mine. Just put some electrical tape over it so it doesn't mar anything.

It is starting to sound like front end damage to me.
 
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