690 Enduro Handlebar Wobble

[cjdad76]

Had my 690 for a couple of years now, rode it through Spaini to Morocco for 3 weeks and apart from the lack of protection at motorway speeds and the uncomfortable seat, the bike has been fantastic!

However! Since I have been back, it has developed a wobble through the handlebar at speeds over 65/70mph. It is not a vibration, but a wobble, most noticeable when accelerating and the front end is light or just by exceeding 70mph. The faster I go the worse it gets, beginning with a slow wobble, getting increasingly worse if I don't back off the throttle and weight the front end of the bike up. This issue was not there before putting 4500mile on her on my Morocco trip.

I have checked the following:
- Front tyre pressure, OK
- Front wheel balancing, OK
- Front wheel bearing, OK
- Head bearings, OK
- Rear tyre was badly worn, so I have replaced/balanced that, OK

I am now at a loss of where to go next. It is unrideable over 70mph.

Has anybody suffered a similar thing?

Any ideas would be appreciated!?!?!

[spooky]

Originally Posted by cjdad76

I have checked the following:
- Front tyre pressure, OK
- Front wheel balancing, OK
- Front wheel bearing, OK
- Head bearings, OK
- Rear tyre was badly worn, so I have replaced/balanced that, OK

I am now at a loss of where to go next. It is unrideable over 70mph.

Has anybody suffered a similar thing?

Any ideas would be appreciated!?!?!

had the same problem on my LC4 640.... with 28lt. tank, 43mm forks and 70/260 rear spring.

solved the problem by reducing the pre-load on the rear 70/260 spring for a few windings, and changed the fork from 43mm and springs with 4.2nm (std. Enduro) to the 48mm fork with 4.4nm spring from the std. Adventure, now all the wobble is gone.
well OK I did fit a SCOTTS steering damper too, but I think that's for comfort and security only when getting a kick on the front wheel on ruff surface, may helps a bit but doesn't solve the wobble problem.

yes care about the ware and balance of the front tyre too.

I know the situation riding such a bike is fringening

hope you get it sorted... start by relaxing the rear spring a bit...

[JonStobbs]

Check your chain, especially the rivet or split link if you have one.Over the years i've found that big singles tend to eat chains faster than multi-cylinder bikes and the weak link is always the actual link itself especially on O or X ring chains.A Scottoiler will help to prolong life but inevitably the link wears out.

[Mickey D]

Tires are usually the cause of this. What front tire are you using? Are you using the stock tires? First thing I would do is go back to NEW Stock tires, front and rear.
Suspension settings can affect a wobble but going to new forks and changing springs is ridiculous. Not required and will not always solve the problem.
Just about every dual sport bike I've owned has had a bit of a wobble depending on tires, speed and sometimes suspension settings. XL Hondas,
XR Hondas, KLR's, DR's, KTM's.

One thing to try is to relax your grip on the bars. Death gripping the bars will make a wobble a worse or induce a wobble.
Double check your head bearing adjustment. (I know you checked them ... but are you sure the adjustment is correct?) Make sure they are not set too tight or over packed with grease.
Suspension: Increase front pre-load a touch. Might help, no guarantees.
But really tires are usually the key. Most 50/50 tires are pretty stable, but knobbies like TKC's, T-63's, MT-21's can get the front into a wobble at certain speeds on pavement. Most times it won't go into a tank slapper ... but for peace of mind you need to reduce the wobble or make it go away totally.

Good luck. Let us know how things go!

[Magnon]

Is the front rim true or is the front tyre wear unven due to heavy braking.

[spooky]

Originally Posted by Mickey D

Suspension settings can affect a wobble but going to new forks and changing springs is ridiculous.

I'm not talking about NEW fork and springs.... eBay buy and sale did cost me about £100 to do the upgrade...

see.. the Enduro has softer springs and is designed for riders up to 75Kg... without a lot of gear on the back.
regarding that I'm using the bike for travelling, the 28lt. fuel tank, and all the stuff loaded on the bike, plus my self about 95Kg plus 13lt. water strapped to the tank, makes a big difference to the stock bike... so... the forks was not designed to cope with the extra weight.... the Adventure set-up is much harder to cope with the weight.... and read the error notes of the WP-manual... it clearly says, that if the bike get this wobble by higher speed, it's the result of either "to soft springs in the forks" or "that the rear spring has a pre-load that is to high" !! regarding the WP-manual: it says, "reduce the pre-load on the back or fit stronger springs in the forks" ... don't forget, often the pre-load on the rear spring is set to high or wrong for the average ride....

well just to justify my upgraded set-up with all the 2nd hand eBay parts... it was well done and didn't cost me a lot, solved the problem of wobble and copes way better for my needs in the long terms.... that's all that's matters to me...
Ohh yae... I had a well worn MT21 on the front... only turned it around and carried on riding it, there was way less wobble as well... my advice:
reduce the rear pre-load by a few windings, and fit a new tyre on the front or turn the one you have around if still ok and only worn a bit.

[spooky]

just a bit of springs and the way it is needed to do some alterations to it for different needs.... OK this chart is for a LC4 640... but gives a pretty good idea why there are so many options to change springs in the first place...

LC4 / WP suspension - front
Fork suspension what spring ?
Spring rate:
3,8 N/mm, 4,0 N/mm rider under 75Kg
4,2 N/mm std. SXC 625 + Enduro 640 used for single rider and competition
4,4 N/mm std. SM + ADV 640 → 2004 used for offroad, rider over 95Kg, light luggage
4,6 N/mm std. SM + ADV 640 → 2005 needed for travel, touring, luggage or 2-persons
4,8 N/mm std. LC8 950 + Rallye 660 needed for heavy luggage + high speed rallye
5,0 N/mm std. SM 640 + SMC 660 '02/'03 only for SM sport

LC4 / WP suspension - rear
Mono shock damper what spring ?
Spring rate:
50/260 for light weight rider
56/260 std. on LC4 from 1993
60/260 std. Competition LC4 1994
63/260 std. LC4 SXC 625 → 2005
66/260 std. LC4 Enduro → 2005
70/260 std. LC4 SM, ADV '97-'05
75/260 std. Rallye, SM → 2004
80/260 for Rallye and very heavy luggage

well this may brighten up some confusions about the importance of changing springs for different purposes.

in case there was some thing suspension wise altered on this 690 for the trip to Morocco... let's say for luggage or so and is still like that... well go back to the standard settings and see if the wobble is gone.

[Mickey D]

Most riders change springs and damping to get better performance off road, not to cure a wobble. Its true, preload settings make a difference on a wobble, so fiddling could cure the wobble ... but may screw up the performance off road. I'd let a PRO deal with it if you are unsure how to proceed.

By changing preload you are altering the geometry of the bike by either raising or lowering the bike ... IE : you are changing the Rake and Trail slightly, which on a bike with a 21" front, can be noticed as making the bike either more stable (less rear preload) or less stable (more rear preload). Adding preload raises the bike UP slightly. Some bikes are very sensitive to this, others not so much.

So stiffness has an effect and the amount of rake and trail that are added or subtracted (via preload or different spring or ride height changes) makes a difference with a wobble and a bikes high speed stability and the way it feels when turning on the road. One can also raise or lower the fork tubes in the triple clamps to affect front to rear bias and alter geometry. I've done this on nearly every off road bike I've owned for the last 20 years) On certain shocks you can also adjust the "Ride Height" rather than adding more preload. There are LOTS of adjustments on modern bikes and shocks/forks to optimize performance. Ideally, they must all be correct and in balance for rider weight, load and intended use.

Based on my test ride on the KTM 690, I'd say the stock suspension is optimized for off road performance. It's on the soft side but good in less aggressive riding. Very plush actually, nearly ideal I thought.

More aggressive riding would most likely require stiffer springs and more rebound damping. Same requirements hold true for a heavily loaded travel bike. But once the weight is OFF the modified bike, it may be a little weird on the paved roads. Trade offs and compromises are part of the deal here.
Can't really be avoided.

[Magnon]

[quote=Mickey D;301195]
Based on my test ride on the KTM 690, I'd say the stock suspension is optimized for off road performance. It's on the soft side but good in less aggressive riding. Very plush actually, nearly ideal I thought.

quote]

Mine must have been made with different suspension to the one you test rode then

[Mickey D]

Maybe you should read your owners' manual and learn how to adjust your suspension. The bike I rode was set up by Scott Harden, former KTM manager and racer. Performed well in the desert in fast riding.

[Magnon]

I'd agree that the suspension is optimised for off road and is quite good in most conditions. It is probably the best available on any out of the box trail bike but the springs are a lot stiffer than on my 530, which means a lot of damping has to be used to be any good, both compression and rebound on the forks are out of range at 15 clicks or less so I'd hardly describe it as plush or on the soft side- just something you get used to.

[colebatch]

I am with Mickey D and suspect tyres ... what tyres are you running? How worn is it, show us a foto of it.

Some off road tyres have no stability at all on the highway, while others are just fine ... and thats new or used.

[cjdad76]

Front Tyre: TKC80, done 4000 miles on it but still pretty good nick, not showing any major signs of wear.

Rear Tyre: Was a badly worn TKC80, originally put on at the same time as the front, now replaced with original Metzeler Sahara as supplied new, only 1000miles on it so nearly new.

I'm running in the Cambrian rally this October, so will have new tyres front and back for that. Guess I will get to see whether they improve the situation!

Tried increasing the pre-load on the rear spring and hardening up dampers all round - no effect whatsoever.

[Mickey D]

Couple other things to check ... just in case you've missed them.

(Sometimes the simplest things can catch you out )

1. make sure the front and rear axle nuts are tightened to the proper torque setting. They need to be very tight! Spacers in correctly ... not turned round or missing?

2. Check the Top Nut on the head stock. I believe it has a torque setting too. (not sure what the 690 has here)

You mentioned you checked steering head bearings ... good. Be sure they are set to proper tension .... not too loose or too tight. Then torque the Top Nut to spec.

Worn tires can do weird things ... and sometimes roads can fool you too.
Here in the USA we have something called "rain gruves" on our Freeways. These are slits cut in the roadway to improve wet weather grip as they channel off water. They cause slightly worn Moto tires to go crazy! Bike frickin' wanders and shakes all over. Point is, road surface can have an affect too.

How she working in the dirt? Balanced? Goes down the track straight under hard acceleration?

Out of ideas. Best of luck.

[Roadcat]

I noticed exactly the same thing yesterday whilst on the motorway on my 690e. A slightly disturbing shimmy when accelerating between 80 and a ton. The heavier I accelerated the worse it got until I slacked off. Interestingly it doesn't happen every time and if I back off the throttle for a few seconds and then open it up again everything is fine.

Checked the obvious things and the only thing that stands out is that the front tyre, although not too badly worn, could do with reversing. The tyres are stock. Haven't checked out the head bearings yet but it's not likely to be the suspension as this is a completely new issue and I haven't touched the suspension for a while.

She's due a service once I get some money, so if I can't solve the problem I'll get the KTM dealer to take a look at it.