High Speed Thumping

[Go Far]

I've got an '06 and it has the thunk. Or a kinda 'cunk' that resembles the old school skateboard wheels on a concrete sidewalk------at SPEED-----

Kinda a hard thumping. Fast and multiple cunks per second.

Like others, I've only experienced this at track speeds starting at about 105, and living out west, we've got a lot of tracks. B)

I'm reading this thread and finding that others are getting the same sensation when on the track and the thought occurs to me that this could be a aerodynamic issue-

Could the centerstand be tappin the undercarriage at speed? That seems to be the mass of the object causing the thump.

Has anyone noticed if a headwind or tailwind effects the speed that the thumping shows up?

 

[SPORT]

Center stand hitting undercarriage? Doubt it as the thumping is VERY consistant. You could almost strike a melody to it. I remember feeling the thump up at the front of the motorcycle; like it qwas from the windshield, maybe in the forks type of feel. Not sure if a drive shaft would give me that feeling...

 

[TownsendsFJR1300]

With the thumping happening at a certain RPM/speed, under load, I would think running the bike on a dyno, at that speed/RPM, the cause of thumping would show. If you can feel the thumping while riding it, you should be able to pinpoint it standing next to it (looking/watching/feeling for vibrations)...

 

[Kirrilian]

With the thumping happening at a certain RPM/speed, under load, I would think running the bike on a dyno, at that speed/RPM, the cause of thumping would show. If you can feel the thumping while riding it, you should be able to pinpoint it standing next to it (looking/watching/feeling for vibrations)...

This was my thought as well since it is really hard to do this while you're riding at these speeds but I don't know where to go for a dyno around here. I am assuming that the dealers would have one?

 

[Dragan]

Kirrilian,

Have you check your engine mounting bolts? You may retight bolts and check if any difference. This is not a big job.

Bolts M12 at 49 Nm (35 ft-lb)

Bolt M10 at 45 Nm (32 ft-lb)

 

[Kirrilian]

Kirrilian,
Have you check your engine mounting bolts? You may retight bolts and check if any difference. This is not a big job.

Bolts M12 at 49 Nm (35 ft-lb)

Bolt M10 at 45 Nm (32 ft-lb)

I will check them but I am curious why you suggested that?

 

[Dragan]

I had some kind of vibration and little bit thumping on the rear left side of the bike. After re-tightening engine mounting bolts, most of the vibration gone and thumping goes to lower level. It still exist but much less then before, almost acceptable.

Hope it will help in your case too.

 

[Bulldog9]

Reading this with interest, have had this or something like this on almost all my shaft driven bikes to varying degree. The only one that has not was my FZ1 (ala chain).

My .02... I dont think it is dangerous or a problem, just the nature of the beast. Found it first in echem.... 1986, went crazy for 2 years trying to find the source of this low oscillating thump thump thump. When it popped up again on my Concours (95), I did the same at first, but ended up finding nothing mechanically wrong, not the tires, wheels, bearings, clutch basket, engine main and trans bearings, or the final drive, wheel bearings, I even retourqued engine mount bolts, changed fork springs, rear shocks, steering head bearings, eventually taking all the body work off the Concours at one point in my fanatical search for the mystery thump. In the end, I put over 100K on both bikes without an issue. Had something similar on the RT I owned, but that bike only lasted 8 months diddnt have the power I needed. On the RT it was more like a hum hum hum than a thump thump thump, but the harmonic was there, either real or imagined. Had a slight amount on the FJR(03), but I only rode that for 3 months (deployed to Afganistan, EX sold it for the $$) When I came back, I got the FZ1. I felt NOTHING on the FZ1.

So my experience with this (FWIW) is not so much with the FJR, but with two other Shaft Driven motorcycles. I found I could control and predict exactly when and where it would occur, usually in top gear, at certain speeds. On the XS it was at about 85, on the Concours about 95 or so. Solution? change something.... Either drop a gear and hold to the speed, raise or lower the cruising speed, or just let it talk to you! If I diddnt want to hear/feel it, I would stay in 4th gear on the XS, and 5th on the Concours, and NO harmonic thump, or I would bump the speed up/down. In the end I lived with it. Of course I spent these many hours of discovery on a closed track

I suggest you ride and find the exact spot the thumping starts, then experiment with the throttle to make it appear and dissapear. When it appears, drop down a gear and hold your speed. I bet if you play with throttle and speed, you will discover it again elsewhere. I think this phenomenon happens when load, speed, ratios and the individual wear of the bike all kind of sync up just right through the final drive and shaft.

Then again, you could just have an out of round rim :dribble:

 

[Kirrilian]

I had some kind of vibration and little bit thumping on the rear left side of the bike. After re-tightening engine mounting bolts, most of the vibration gone and thumping goes to lower level. It still exist but much less then before, almost acceptable.Hope it will help in your case too.

Ok thanks, I was just wondering where you were getting that from and that is definitely possible considering that my stem nut was only hand tight when I got the bike :blink:

 

[Kirrilian]

Reading this with interest, have had this or something like this on almost all my shaft driven bikes to varying degree. The only one that has not was my FZ1 (ala chain).
My .02... I dont think it is dangerous or a problem, just the nature of the beast. Found it first in echem.... 1986, went crazy for 2 years trying to find the source of this low oscillating thump thump thump. When it popped up again on my Concours (95), I did the same at first, but ended up finding nothing mechanically wrong, not the tires, wheels, bearings, clutch basket, engine main and trans bearings, or the final drive, wheel bearings, I even retourqued engine mount bolts, changed fork springs, rear shocks, steering head bearings, eventually taking all the body work off the Concours at one point in my fanatical search for the mystery thump. In the end, I put over 100K on both bikes without an issue. Had something similar on the RT I owned, but that bike only lasted 8 months diddnt have the power I needed. On the RT it was more like a hum hum hum than a thump thump thump, but the harmonic was there, either real or imagined. Had a slight amount on the FJR(03), but I only rode that for 3 months (deployed to Afganistan, EX sold it for the $$) When I came back, I got the FZ1. I felt NOTHING on the FZ1.

So my experience with this (FWIW) is not so much with the FJR, but with two other Shaft Driven motorcycles. I found I could control and predict exactly when and where it would occur, usually in top gear, at certain speeds. On the XS it was at about 85, on the Concours about 95 or so. Solution? change something.... Either drop a gear and hold to the speed, raise or lower the cruising speed, or just let it talk to you! If I diddnt want to hear/feel it, I would stay in 4th gear on the XS, and 5th on the Concours, and NO harmonic thump, or I would bump the speed up/down. In the end I lived with it. Of course I spent these many hours of discovery on a closed track

I suggest you ride and find the exact spot the thumping starts, then experiment with the throttle to make it appear and dissapear. When it appears, drop down a gear and hold your speed. I bet if you play with throttle and speed, you will discover it again elsewhere. I think this phenomenon happens when load, speed, ratios and the individual wear of the bike all kind of sync up just right through the final drive and shaft.

Then again, you could just have an out of round rim :dribble:

It is interesting that you have seen this from other shaft driven motorcycles, I dont have any experience as this is my first shaft drive. I have tried different RPMs, gears, and speeds and the only way I can get it to do it is in 5th gear going those speeds. But on the other hand, it is stretching it a bit to go that fast in 4th gear!

 

[TownsendsFJR1300]

With the thumping happening at a certain RPM/speed, under load, I would think running the bike on a dyno, at that speed/RPM, the cause of thumping would show. If you can feel the thumping while riding it, you should be able to pinpoint it standing next to it (looking/watching/feeling for vibrations)...

This was my thought as well since it is really hard to do this while you're riding at these speeds but I don't know where to go for a dyno around here. I am assuming that the dealers would have one?

Most dealerships down here don't have one however the shop I frequent, an aftermarket high performance MC shop, (Superbikes and Ski in Ft Myers, Fl) has one as they do jet kits, powercomanders, etc... I do know Harley Davidson of Gainesville has a dyno.... I do believe strapping the bike down, getting it to speed, (while standing along side it while its doing it) should be revealing...

 

[Kirrilian]

I am going to ask around and see who may have one but I have a feeling that what Bulldog9 said may be true, what if it is just something that is inherent with shaft drives? My only rebuttal to that is why isn't everyone having this issue then? Until then I'll stay off the "track" LOL, its too damn cold to go to the track anyway!

 

[rhody]

Reading this with interest, have had this or something like this on almost all my shaft driven bikes to varying degree. The only one that has not was my FZ1 (ala chain).
My .02... I dont think it is dangerous or a problem, just the nature of the beast. Found it first in echem.... 1986, went crazy for 2 years trying to find the source of this low oscillating thump thump thump. When it popped up again on my Concours (95), I did the same at first, but ended up finding nothing mechanically wrong, not the tires, wheels, bearings, clutch basket, engine main and trans bearings, or the final drive, wheel bearings, I even retourqued engine mount bolts, changed fork springs, rear shocks, steering head bearings, eventually taking all the body work off the Concours at one point in my fanatical search for the mystery thump. In the end, I put over 100K on both bikes without an issue. Had something similar on the RT I owned, but that bike only lasted 8 months diddnt have the power I needed. On the RT it was more like a hum hum hum than a thump thump thump, but the harmonic was there, either real or imagined. Had a slight amount on the FJR(03), but I only rode that for 3 months (deployed to Afganistan, EX sold it for the $$) When I came back, I got the FZ1. I felt NOTHING on the FZ1.

Bulldog9,

I think with your experience on every shaft drive bike you have owned says that inherent in all shaft drive systems is the potential given a certain rpm, load (usually heavy), gear ratio (usually 5th or top) that any shaft drive bike whether it be a Yamaha or Kawasaki lives a set of circumstances that cause a thump, clunk, cunk or however you choose to describe it occur.

Since you were thorough and almost fanatical in removing every potential caused for the thump, that leads me to a question.

That is, is there a factory rep or person who may have access to a Yamaha/Kawasaki/Honda, engine/shaft drive engineer to ask them what in the design of the engine/transmission coupling that causes this. Since this quirk has been around for as long as you describe, someone, somewhere must have an official name for it. Hopefully it's not something like PTSDSD, (post traumatic shaft drive system design disorder !!! lol)

I know some knowledgeable soul out there has the answer..... this thread now has 71 replies and I think a bunch of us would like to know what the "root cause" really is....

P.S.

I like TownsendsFJR1300's idea of strapping it to a dyno to make it happen, but wonder if the downward force of the straps would dampen it, if not and you can hear/feel it, we still are no closer to a good explanation of why it happens. All we can say with certainty is that the guy standing on the bike may hear and or feel it, and those around him may hear it as well.

 

[Kirrilian]

PTSDSD, (post traumatic shaft drive system design disorder !!! lol)

Well I guess we have a formal name for this affliction now heheh

But wouldn't it be PTSDSDD?

Try saying that fast 10 times!

 

[rhody]

PTSDSD, (post traumatic shaft drive system design disorder !!! lol)

Well I guess we have a formal name for this affliction now heheh

But wouldn't it be PTSDSDD?

Try saying that fast 10 times!

Yeah I left off the last D before I posted, then noticed, I am not the anal enough to go edit it though.....

 

[Bulldog9]

Bulldog9,
Since you were thorough and almost fanatical in removing every potential caused for the thump, that leads me to a question.

That is, is there a factory rep or person who may have access to a Yamaha/Kawasaki/Honda, engine/shaft drive engineer to ask them what in the design of the engine/transmission coupling that causes this. Since this quirk has been around for as long as you describe, someone, somewhere must have an official name for it. Hopefully it's not something like PTSDSD, (post traumatic shaft drive system design disorder !!! lol)

I know some knowledgeable soul out there has the answer..... this thread now has 71 replies and I think a bunch of us would like to know what the "root cause" really is....

P.S.

I like TownsendsFJR1300's idea of strapping it to a dyno to make it happen, but wonder if the downward force of the straps would dampen it, if not and you can hear/feel it, we still are no closer to a good explanation of why it happens. All we can say with certainty is that the guy standing on the bike may hear and or feel it, and those around him may hear it as well.

When I first noticed it on the XS, It bothered me and I played around a bit, and just accepted it as part of the bike. It was about 7-8 years old at the time (30 years now... :dribble: ) and had maybe 3000 miles on it. But 8-10 years later when I bought the Concours new is when I really went nuts thinking there was something wrong. It was a new bike, shouldnt do this, so over the first 2-3 riding seasons I experimented. I had forgotten all about this. Looking forward to seeing if my FJ will have the same problem. From June of next year till December, I will be commuting from Columbia SC to Alexandria Virginia every weekend, I'm sure on that long track called I95 that stretches between them that I will have ample opportunity to see if when and where this occurs.......... Lets see, 5th gear about 110?

Looking forward to the Dyno test myself.

 

[Kirrilian]

Bulldog9,
Since you were thorough and almost fanatical in removing every potential caused for the thump, that leads me to a question.

That is, is there a factory rep or person who may have access to a Yamaha/Kawasaki/Honda, engine/shaft drive engineer to ask them what in the design of the engine/transmission coupling that causes this. Since this quirk has been around for as long as you describe, someone, somewhere must have an official name for it. Hopefully it's not something like PTSDSD, (post traumatic shaft drive system design disorder !!! lol)

I know some knowledgeable soul out there has the answer..... this thread now has 71 replies and I think a bunch of us would like to know what the "root cause" really is....

P.S.

I like TownsendsFJR1300's idea of strapping it to a dyno to make it happen, but wonder if the downward force of the straps would dampen it, if not and you can hear/feel it, we still are no closer to a good explanation of why it happens. All we can say with certainty is that the guy standing on the bike may hear and or feel it, and those around him may hear it as well.

When I first noticed it on the XS, It bothered me and I played around a bit, and just accepted it as part of the bike. It was about 7-8 years old at the time (30 years now... :dribble: ) and had maybe 3000 miles on it. But 8-10 years later when I bought the Concours new is when I really went nuts thinking there was something wrong. It was a new bike, shouldnt do this, so over the first 2-3 riding seasons I experimented. I had forgotten all about this. Looking forward to seeing if my FJ will have the same problem. From June of next year till December, I will be commuting from Columbia SC to Alexandria Virginia every weekend, I'm sure on that long track called I95 that stretches between them that I will have ample opportunity to see if when and where this occurs.......... Lets see, 5th gear about 110?

Looking forward to the Dyno test myself.

No no no no no, we're testing on the "track" see? Because doing these speeds on public streets is illegal and dangerous and I'm sure that no one on this board does anything like that...

Also, I put a few feelers out for a dyno, we'll see what happens. I'm not taking it to a dealer unless I absolutely have to, I doubt they have one anyway.

 

[ghost]

Did you experience the problem before you mounted the Road Smarts ?

I'd never had any high speed problems at all until I tried these tires -"thumping" started at about 95 and felt like I had lost a tire weight. I rebalanced the front tire - it made no difference.[ Tire was okay BTW ]

I replaced the front tire with a PR 2 and the thumping stopped - at least at any speed I was willing to try on the street.

The rear tire was not replaced. [ Did you notice the R/S front and rear tires are manufactured in different countries ? France /Japan ]

I'd bet if you replaced the front tire, your thumping would disappear.

 

[OGRE]

The thumping I'm experiencing happens regardless of tires... from brand new to old, PR2's to Z-06's.... I also want to clarify that the noise/vibration I feel is somewhat annoying, but I'm not worried about it. It doesn't seem like anything that is gonna cause the drive train to fail or cause a wreck. It almost feels like too much torque with too little revs or something... kinda like if you if you slow for a stop light, light changes, you release the clutch still in 5th at 10-15 miles an hour and try to twist the throttle. The bike almost shudders, aproximatly 2-3 thumps per second at 100 mph. I'm not gonna take the bike apart or rush to the shop with it, I'm just curious about the cause.

 

[Kirrilian]

Did you experience the problem before you mounted the Road Smarts ?
I'd never had any high speed problems at all until I tried these tires -"thumping" started at about 95 and felt like I had lost a tire weight. I rebalanced the front tire - it made no difference.[ Tire was okay BTW ]

I replaced the front tire with a PR 2 and the thumping stopped - at least at any speed I was willing to try on the street.

The rear tire was not replaced. [ Did you notice the R/S front and rear tires are manufactured in different countries ? France /Japan ]

I'd bet if you replaced the front tire, your thumping would disappear.

It did it with the stock tires (Metzlers I think?) and it is still doing it with the RoadSmarts.