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speed wobbling happening at +120km/h

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I'm approaching 11,000km on the bike and never had issues with speed wobbling until recently. I returned from a ride in the dirt (no major hits and/or drops) without any issue on the 120km of highway to get home but then washed my bike the next day and the wobbles haven't stopped since. My tires were a bit low at 17psi so I aired them up to 22psi – I typically ride 20psi but gave them a bit more to see if it remedied the problem. I'm on my second set of the stock pirelli mt21 which are pretty much new with only about 20% wear.

I bent the front rim slightly last november but the shop straightened it out as best as they could and balanced the wheel with some weights when the new front was installed. Again, no issues with wobble until recently. I had my suspension guy dial the settings in november as well and haven't screwed with them since. The only thing I can add is that my rear shock was weeping a bit of oil awhile back so ktm is supplying me with a rebuild kit under warranty which I will be having installed in a few weeks.

I'm not mechanical so my first place to point the finger was the leaking shock but my dealer who specializes in suspension is very confident that there isn't anything wrong with my shock and some oil residue is common. I also brought it to my independent shop around the corner and they gave it a quick 20-minute look-over. I was a bit frazzled by the wobbling so I just showed up at their door without an appointment. They weren't able to do a full-service investigation right then as it's peak season but they still took the time to check usual culprits like play in the wheel bearings, steering head bearings, suspension action, etc. Obviously they said they need more time with the bike to properly review everything but they didn't notice anything glaring at the moment. Even they said the rear shock seemed fine – that it wasn't responding as if it were out of oil.

My previous bike was the honda crf 250L and these 2 dual-sports are the only bikes I've ever owned so I'm used to the unstable characteristics of these types of bikes. I'm telling ya though – there's some weird shimmy this bike is doing once I push above the 120km/h range. And even if I find a groove at 135km/h the bike feels hypersensitive to even the small things such as uneven road, lane changes, turning my head, etc. I've tried adjusting body-position, going super-light grip, etc, etc. but something just feels uncomfortable with the dynamics once the speeds get higher. Even when there's very little wind it feels similar to when the bike buffets during heavy winds. And I've often ridden in very heavy winds – even on the skyway bridge – so I'm familiar with squirrelly dancing. The ONLY thing I can speculate at this point is the fact I did purchase a new helmet. However, it is still the same motocross helmet configuration as previously and even the same brand, just a different model.          

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The MT-21 front is suspect. I destroyed one in one ride. Hard front brake will cause the knobs to flex and wear at an angle. I have had much better luck with the T-63 front with it's shorter knobs. The T-63 is Good enough on dirt too.

Also the 690 has the rear tank, less weight on the front which contributes to speed wobble. Any weight on the rear (camping gear) makes it worse too. 

After stories of near death speed wobble crashes on the 950 I always put a damper on my "Adventure bike". Good insurance.. 

My 690 is sketchy over 80mph. With a good front tire it will go 100mph... I know guys that run up over 80 on the 690. I'm good at just over 70 on it. 

Summary -

New front tire, reduce rear weight, steering damper. 

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MT-21 is my go to tire for dual-sports with emphasis on dirt, 4 bikes now including the 690.

The tire is non-directional, or bi-directional, or bottom line you can flip it. I do so a bit after it starts showing the "angled" wear. As the nobs get shorter it wears more evenly. I'm guessing 50-100% more life, depending on rider subjectivity.

Scotts appears to be the damper of choice, but if I bought one it would be for off road, primarily for rocks and very soft cinders at speed. On road I have no issues with handling except getting blown around a bit in heavy winds which I suspect a damper would not assist.

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I've not found any issues with wobble at speed. But, I don't have a rack yet, so I've not loaded up the back. Time will tell. Still on the stock Pirelli MT21 and I like them. Not terrible on the road and plenty of grip off.

I plan to install a Scotts steering stabilizer, but like an idiot, I sold the one I had when I bought my Triumph Tiger 800XC. I guess I thought it was going to be "the" bike. Why Scotts, the product flat out works and the guys behind it support it fully and know their stuff. 

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so I finally brought the bike in to have the rear shock rebuilt kit installed/adjusted under warranty and the bike shoots straight as an arrow. I'm not mechanical so some of the following verbiage may be a little mixed up or off but he adjusted the sag (I believed he lowered it) and did some further tweaks to the rebound and possibly compression. He was saying how the bike's suspension, although adjustable, is sprung a bit too much on the high end in order to be able to accommodate worse-case scenarios such as luggage, passengers, etc. And because I weigh 170 the rear was slightly off and sitting a bit high so with the rebuild kit he was able to lower the geometry and dial in the settings more specific to my weight + riding. Very pleased with how she tracks now – 140-150km/h like butter. The only thing is because it's now sitting a bit lower I tipped it over like a moron while I was washing it the other day – I may take a bit off the kickstand so it isn't so vertical. 

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Just put on a Motoz Tractionator Desert H/T on the front. Not much time on it, but a slight weave at 75+MPH. Not bad, and not always. :excuseme:

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