[Sai Werd]

Please help!!!


I've had my DR650 laced with Excel Rims on the stock hubs for sometime now. My problem is that at high speed 75, 80, 90+ I get a high speed wobble. The front end gets really flighty, almost to the point of a tank slapper.

What can I do? I've tried a few things already; raising the forks through the trees, changing to a thicker fork oil, re-balancing my front wheel.

Please let me know your thoughts. I'd really love to geet tis sorted soon!

Thanks!

 

[Crow]

Fork brace

steering stabilizer

 

[YZFnwithme]

Raising the forks probably made it less stable, rather than more.

Good luck.

 

[Sai Werd]

Fork brace

steering stabilizer

I have an SRC Fork Brace.

 

[TomCRMI]

Did you try changing tire pressure ?
Also different types of tires help reducing the "shimmy"
... my CBR1000F was pretty bad also, especially when rolling out with throttle shut at around 70-80 mph.
I then switched to a Bridgestone BT-50 or 54 ??? don't quite remember because it's been a while ... anywho ... it totally eradicated the issue. Never had it again after that, even when the tire was almost bald.

 

[Sai Werd]

I run Avon Distanzias. They are "supposed" to be great tires! I love their grip so far. Hate to have to change tires already (only 1500 miles at most!).

 

[RichieB]

Raising the forks probably made it less stable, rather than more.

Good luck.

+1

My XR650R wobbled worse when i raised the forks up in the triple clamps.


If you lower the front you gotta lower the rear too.

 

[Crow]

Or ya might try raising the front back up and then lowering the rear. You have now effectively quickened your steering(reduced your rake). Lowering the rear with the stock height up front would slightly increase the rake and slow things down a bit up there. Just an idea.

 

[nmilne]

What pressures are you running?

 

[Sai Werd]

What pressures are you running?

Mid 20's (25-28psi).

 

[Quickbrit]

You might want to try relaxing...

Sometimes you can inadvertantly put input into the bars. Try and grasp the bike with your thighs using a looser hand grip and countersteering with your palms rather than pushing and pulling.

Just my 2c's

MikeE

 

[apa]

Is the wobble on Accel or Decel? What is your shock preload set at?

 

[Sai Werd]

Is the wobble on Accel or Decel? What is your shock preload set at?

The wobble is at high speed whether I'm accelerating or keeping a constant speed. It feels like its on the verge of a tankslapper, when the front gets really light and gets all flighty.

I'm debating on changing tires to see if its does anything. I've already sent the rim back to East Coast just to make sure there is no hop in the rim.

Kinda running out of options.

 

[Canadian_SMR]

Im going to agree with Quickbrit on this one. See if there is any thing you can find about your riding style that could do it. are you locking your arms on the bars? white knuckled death grip? As well, check to see if your sitting on the back of your seat, try crowding the tank abit and see if that makes it go away? Some of the guys up here who are running there race bikes on quick tracks cut holes in there front number plate *since you most likly have a light on it you cant do that* and cut there tank shrouds *the long plasticy things from the front of your tank* just put some holes in them about an inch around and 5 on each or so. to reduce the wind getting under it and lifting it up. i rember my lc4 did about the same thing at around 80 mph. But then my dads duke2 dident at all. Some times its just the nature of the beast. Also to look on your tire when you mount rubber to it make sure it evenly seats completly around it and take out the tire lock on the interier of the rim if you havent yet. Sounds kinda stupid but i watched a good rider *shafty machanic* ride 2 weekends ago and his rear wheel was hoping 2 inchs in the air and he dident have a clue what it was. :infrandom

 

[K-9]

you might also try snugging up the stearing head bearings, not too tight, but good & snug, btw, yes the front end up is the most stable at high speeds.

 

[Sai Werd]

No white knuckles, and pretty much balls on the tank.

I have noticed that when the wobble happens, if I lean all of my weight over the front of the bike it calms down. That's why originally I thought to raise the forks through the yokes to put more weight over the front end.

BTW, the DR650 doesn't have tank shrouds.

Also, once I can find a wrench big enough, I will make sure the steering head is tight.


ANYONE ELSE?!?!?!? :hammer:

 

[brian]

If you put on a slick it will help, abit.........maybe......You are goin 80-90 mph......shit thats fast......when I'm doin that speed my KX does the same thing a little less dramatic,tuck and hold on its the nature of the beast........Its a "Big" dirtbike with stock/soft suspension, ain't designed to do what you want....it isn't a sport bike for gods sake.....take the front fender off, give it another try, get your suspension lowered abit and revalved etc etc etc I put my Distanzias back on a few weeks ago for a race and was surprised how weird they felt compared to rains and a slick.......My MZ street tard gets light on the hwy past 75, street tires helped abit and stiffer suspension, I even lowered the bike (abunch) still feels the same way, its a big bike with older technology frame ya da ya da..............

 

[apa]

Sounds like a tire problem to me but...... Check your stearing head bearings by puting it on a stand so the front wheel is off the ground then take both fork bottoms in your hands and push and pull on the forks. If the bearings are loose you will feel a clunk clunk. While it is off the ground turn the bars from one side to the other. Do you feel any knotching or sticking?

 

[Sai Werd]

Sounds like a tire problem to me but...... Check your stearing head bearings by puting it on a stand so the front wheel is off the ground then take both fork bottoms in your hands and push and pull on the forks. If the bearings are loose you will feel a clunk clunk. While it is off the ground turn the bars from one side to the other. Do you feel any knotching or sticking?

I just changed the fork oil and haven't felt any free play, nor knotching or sticking.


argh!

 

[Kwota]

No white knuckles, and pretty much balls on the tank.

I have noticed that when the wobble happens, if I lean all of my weight over the front of the bike it calms down. That's why originally I thought to raise the forks through the yokes to put more weight over the front end.
:hammer:

raising the forks in the triples will steepen the steering head angle which will make the bike turn in quicker or be more twitchy and responsive.

changing to a wider profile tire on a sportbike, say a stock 60 to a 70, means that you'd have to raise the forks to compensate for the extra tire height and its slower steering effect.

the front of my crf gets fairly light on the gas at high speed, but i'd say the key to your solution is to play with the rear shock and return your forks to stock level in the triples. softening the rear will relax that steering head angle further and will give you a bit more stability. if its only doing it when you're on the gas it just means that the bike wants to wheelie and its at the point where the front wheel is just skipping along the pavement.

the thing is that there's many factors at play here. tires/suspension settings/body position/death grip on bars/wind resistance/pavement/tire pressure/steering bearings/wind; just try to eliminate as many as you can while you're figuring it out. by the way, that's pretty quick for a motard, and that could be it too...