2015 KLR650, Tourist down at 70 mph from speed Wobble! - Kawasaki KLR 650 Forum
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post #1 of 22 Old 06-21-2019, 09:47 PM Thread Starter
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2015 KLR650, Tourist down at 70 mph from speed Wobble!

I had a tourist from the PNW in my shop yesterday afternoon. He had gone down at about 70 mph by his best guess, on a straight section of highway.
The incident was observed by a following motorist and an oncoming deputy sheriff, near Yellowstone Nat'l Park. The deputy sheriff told the rider that he was certain that he would be calling the coroner, instead of assisting the rider to pick-up his heavily loaded KLR. The front tire left numerous crescent shaped skid-marks on the highway before going flat down.

The rider said that the bike had had higher speed wobbles even on the OEM tires since new.
The rider wished for me to attempt to straighten his twisted front forks, so his barely bent handlebars were better aligned with the front wheel. The upper fairing was held together and onto the bike with Duct Tape and he was continuing on south to Colorado & beyond. The RH Tusk pannier was well bent and the lid no longer could be fitted & latched, so held sort of on with bunjie cords.

As I stepped out the door to look at the situation, I commented from 40 feet away from his bike that I did not like the scalloped look of his D606 knobby front tire. He replied they were only about 1300 miles used. I pointed out the direction of the Vee pattern of the front knobs and also asked about his tire pressures. He claimed mid 20's psi.

His bike had a center stand & the 2 of us hoisted the overloaded mule up. I loosened the upper triple clamps and the lower axle clamps and straddled the front wheel and wrench on the handlebars to un-twist the forks, several times. All while discussing various possibilities of the cause of the incident. I then loosened the front axle nut, it was no where near the 65 ft lb recommend torque. Discussed that possibility.
With a few more hearty twists I had the front tire, front fender & handlebars pretty much back in-line. I offered to rotate the front D606 to the inverted 'V' contact pattern and showed him a Shinko E705 front with Front & Rear directional arrows to help explain. But also suggested that it might be better to just install the Shinko to get rid of the severely scalloped front D606. The Rear D606 was severely 'Squared Off' also, and we lightly discussed its possible bearing on the incident.

Finally I handed him a digital tire gauge for him to check his knobby tire pressures.
18 PSI in the severely scalloped Front tire and 20 PSI in the squared Rear tire. I've no idea how much or how little dirt roads he had ridden to get to Yellowstone Park, but it is 160 miles of asphalt from Grassy Lake road in the Rockefeller Parkway between the parks (Grand Teton & Yellowstone) to Lander WY.

I suggested a minimum of 34 front & 34 rear to continue his trip to Rawlins WY, on asphalt and on into Colorado. Which he conceded to inject. We tightened all of the previously loosened hardware. We could not feel any slack in the steering bearings and the top stem nut was tight.

He suggested that he would call me from some point farther south with an update and rode across the street to the restaurant for a hamburger & fries.

I recon the he just has a 'shit happens' attitude and wish him the best. I hope that he has no more wobbles & does call me.

The moral of this story might be, higher speeds need higher tire pressures. I hope I hear from him, soon.

pdwestman
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post #2 of 22 Old 06-22-2019, 06:23 AM
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Interesting tale. He seems to have been a lot more nonchalant about his situation than I would have been. I believe I would have been asking you if there was a store nearby where I could go get some replacement underwear while waiting on you to mount me some new tires.........

Then again, I'll admit I'm probably overly sphinctorial about tire condition and pressures. The insides of my riding gloves are probably dirtier than the outside due to putting them on uncleaned hands after spinning/inspecting tires and checking pressures.
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post #3 of 22 Old 06-22-2019, 08:36 AM
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Scary sheit.. after that I’d likely stop riding bikes all together.
I’m not sure his continuing on is big balls, or stupidity.

2016 KLR 650
2017 BMW S1000RR (traded in for
2018 Ducati V4S
1983 GL1100 Goldwing
2017 Yamaha R1

Last edited by dan filipi; 06-22-2019 at 10:48 AM.
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post #4 of 22 Old 06-22-2019, 09:39 AM
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I’m understanding that he rode away on the Dunlop’s??

I have a feeling you may be reading about him rather than hearing from him.

My Kaw Barn - 2004 KLR, 2006 Concours (sold), 1997 Bayou 400.

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post #5 of 22 Old 06-22-2019, 12:13 PM Thread Starter
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Yes, he intended to continue his journey on the Dunlop D606's.

I should have showed him the partially used dirt bike rear knobby leaning against my outside wall, worn out from the Inside. The cords are chaffed loose on the inside and that allows them to 'saw thru' the inner tubes. This is also caused by Too Low of air pressure & too much flexing.

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting

Last edited by pdwestman; 06-24-2019 at 01:49 PM. Reason: spelling
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post #6 of 22 Old 06-25-2019, 09:44 AM
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Worn D606's and low pressures sure could have been a contributing factor though I doubt it was the cause of his accident. Heavy loads, load distribution, aero, suspension setup and the rider are all more likely root causes IMO.

Cheers,
Dave
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post #7 of 22 Old 06-25-2019, 12:58 PM
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Originally Posted by DPelletier View Post
Worn D606's and low pressures sure could have been a contributing factor though I doubt it was the cause of his accident. Heavy loads, load distribution, aero, suspension setup and the rider are all more likely root causes IMO.

Cheers,
Dave
I suspect all of the above made some contribution, but it is necessary to match tire pressure to load and speed. If a bike is loaded at or above the GVWR, then the tires should be pretty darn close to their maximum rated pressure also. The KLR has a very flexible frame and forks compared to other bikes I have owned (well no worse than my old 100 Kawasaki). Tires get more flexible when they are hot as anyone who changes their own tires knows very well. A heavy load with low tire pressure will get the tires quite hot and that combined with the already flexible tires due to the low pressure and the flex in the forks and chassis means that a tank slapper is just waiting to happen.
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post #8 of 22 Old 06-25-2019, 02:28 PM
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I suspect all of the above made some contribution, but it is necessary to match tire pressure to load and speed. If a bike is loaded at or above the GVWR, then the tires should be pretty darn close to their maximum rated pressure also. The KLR has a very flexible frame and forks compared to other bikes I have owned (well no worse than my old 100 Kawasaki). Tires get more flexible when they are hot as anyone who changes their own tires knows very well. A heavy load with low tire pressure will get the tires quite hot and that combined with the already flexible tires due to the low pressure and the flex in the forks and chassis means that a tank slapper is just waiting to happen.
Yep; as I said, I think the tires/pressures could well have been a contributing factor and he had a bad tire choice (worn D606 front in the "backwards" direction) and the tire pressure was lower than I use even offroad......but I just don't think it's THE reason

...and while I'll concede the frame and forks are more flexible than some other bikes, I still think weak suspension (inadequate springrate AND damping) is a large contributor combined with suspension set up (sag) and loading. I personally don't think the fork diameter is as much a problem as many do.

FWIW, I rode my KLR with my D606/MT21 combo at 22PSI at 70+mph in sweeping highway turns with one hand on the bars with zero instability at the last dual sport event.

2 cents,
Dave
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post #9 of 22 Old 06-25-2019, 08:12 PM
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Originally Posted by DPelletier View Post
Yep; as I said, I think the tires/pressures could well have been a contributing factor and he had a bad tire choice (worn D606 front in the "backwards" direction) and the tire pressure was lower than I use even offroad......but I just don't think it's THE reason

...and while I'll concede the frame and forks are more flexible than some other bikes, I still think weak suspension (inadequate springrate AND damping) is a large contributor combined with suspension set up (sag) and loading. I personally don't think the fork diameter is as much a problem as many do.

FWIW, I rode my KLR with my D606/MT21 combo at 22PSI at 70+mph in sweeping highway turns with one hand on the bars with zero instability at the last dual sport event.

2 cents,
Dave
I donít think there is a THE reason, as changing almost any of the variables may well have eliminated the problem. However, tire pressure is probably the easiest one to change and thus I would consider it the primary issue as it is the one that could have most easily been changed to avoid the problem.

Springs and shocks are very unlikely to be a factor in a high speed wobble. The suspension is hardly ever moving much until things get really ugly. The issue is a resonance between the tire, wheel, fork, and frame due to their flexibility.

I have not had any noticeable instability with my KLR either, but I have had it only up to 70 or so. However, the flex in the forks and chassis is very pronounced compared to my BMW. If I do a quick swerve on the KLR, I get oscillations at both the start of the swerve and the recovery that are very unnerving. My LT on the other hand, is rock solid. It enters a swerve and exits a swerve with no noticeable oscillation at the transitions. It simply goes where it is pointed. However, it has a large casting for the main frame and the Hossack style front suspension is very rigid. And the cast wheels are more rigid than spoked wheels, so it is no surprise that it is far, far more solid during high speed transitions as compared to the KLR.
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post #10 of 22 Old 06-26-2019, 09:59 AM
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I donít think there is a THE reason, as changing almost any of the variables may well have eliminated the problem. However, tire pressure is probably the easiest one to change and thus I would consider it the primary issue as it is the one that could have most easily been changed to avoid the problem.

Springs and shocks are very unlikely to be a factor in a high speed wobble. The suspension is hardly ever moving much until things get really ugly. The issue is a resonance between the tire, wheel, fork, and frame due to their flexibility.

I have not had any noticeable instability with my KLR either, but I have had it only up to 70 or so. However, the flex in the forks and chassis is very pronounced compared to my BMW. If I do a quick swerve on the KLR, I get oscillations at both the start of the swerve and the recovery that are very unnerving. My LT on the other hand, is rock solid. It enters a swerve and exits a swerve with no noticeable oscillation at the transitions. It simply goes where it is pointed. However, it has a large casting for the main frame and the Hossack style front suspension is very rigid. And the cast wheels are more rigid than spoked wheels, so it is no surprise that it is far, far more solid during high speed transitions as compared to the KLR.
I'm familiar with other bikes; I've had 41 so far. I still say the suspension, setup and loading are more likely "primarey" causes than tires or spindly forks but I concur that a number of "weak links" add together to manifest the problem and I agree that I would start on this particular bike by changing the tires and increasing pressure to try to reduce the effect.

FWIW, my standard wobble post:

Way too many people think that addressing the symptoms by dealing with handguards, fenders, fork braces, etc. are the answer rather than dealing with the real issue which is related to suspension setup and loading. I'm not convinced that the KLR is any more susceptible to instability than any other bike with long travel, lightly damped suspension and the Owner's have a propensity for severe and uneven loading.

There are some problems that need to be checked;
- bad/lose head bearings
- condition of wheel bearings and suspension bushings
- wheel and tire condition and appropriate tire pressures.

.....beyond that, It's settings;
- proper sag settings and adequate damping
- proper bike loading
- avoiding inappropriately un-aerodynamic loads

addressing the symptoms rather than the cause can help but IMO shouldn't be done until all the aforementioned items are checked and corrected if necessary. Nonetheless these can help stability;

- fork brace
- smaller fender or lowered fender (I use a polisport as I hate both the supermoto and low mounted fenders)
- consider tank bags instead of putting everything in huge panniers which affects both weight loading and aerodynamics.


My 2001 had some high speed issues that went away as soon as the sag was set properly....and after my Cogent suspension was installed, both my KLR's have been rock steady.....even with full knobbies and low tire pressures (20 - 22PSI). Lastly, as others have mentioned, the rider also plays a part; keep a relaxed light grip on the bars and don't tighten up. Changing your position (move forward/lean forward) can help too.

2 cents,
Dave
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