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Speed Wobbles - SMS 630

notoriouz

notoriouz

Husqvarna
A Class
I'm curious, for those of you that ride 630's, what speed can you get up to before the speed wobbles are too much?

I'm trying to figure out if there is something wrong with my bike; I've read of people getting to upwards of 180 kmph.

I did the same thing I do with any new toy and took the bike to the highway and pinned it, I got to 150 kmph and had to back off because the speed wobbles were so bad.

Can anyone chime in and let me know what's up on your end? Just trying to get some information!
 
Could be a bunch of things... Tire pressure, suspension, did you change your tire and forget to bounce the front end before snugging up pinch bolts? Some people need to balance their wheels. I don't have that problem. I can pull 100mph and its smooth as glass.
 
1lunger said:
Could be a bunch of things... Tire pressure, suspension, did you change your tire and forget to bounce the front end before snugging up pinch bolts? Some people need to balance their wheels. I don't have that problem. I can pull 100mph and its smooth as glass.
Click to expand...

Wow, you just mentioned a lot of simple things that completely slipped my mind when I was thinking about it. I'll have to check my tire pressure tomorrow. When you say "bounce the front end", what exactly do you mean? I had my wheels taken off the bike to have the rims painted, when I had them put back on I had the front wheel re-balanced. I didn't have the gear to take the wheels off myself.

Is there some sort of simple test I could do myself to see if it may be my suspension? Something tells me it wont be, but I'd like to be positive.

Sorry for any lame questions I'm asking, I'm a "newb" but I'm trying to keep learning. Motorcycles grab my attention like nothing ever has.
 
Have someone help check your sag in the rear. Unload the rear (hold it up) and measure the distance from the tire or axle to the fender.
Next, sit on the bike in your normal position and measure the same points. The distance should be ~3.5-4" less. If it's less, you start reducing effective rake/trail in the front, making it less stable.

Couple quick questions:
Was the bike new when you got it?
How much do you weigh?
What kind/size tires?
 
Alright, I'll get a buddy to help me check the rear suspension sag as soon as I can, it's rather miserable weather-wise around here lately.

The bike was not new, I got it second hand; he was the only other rider. The bike had around 5100 kilometers (3168 miles) at the time I purchased it.
I'm only little, lol. I weigh about 130 pounds.
The tires that I'm using are Continental ContiForce's and I believe that they are 4.5 150's. I could be wrong on the size, I'm not certain but I'm pretty positive.
 
Ok, at 130 lbs, you're about 100lbs lighter than than the person the bike was set up for from factory :p

My guess is that your sag is short. If it is, loosen the spring perches on the rear shock and screw them up on the shock body to increase the sag and effectively lower the rear.

Ultimately, you'll probably need a lighter shock spring.

ETA: When I'm gunning down the highway, I'll slide my butt way back on the seat to get more weight on the rear, and it's plenty stable up to my 110mph top speed.
I'm 200lbs without gear, though.
 
I'll have a look the next chance I get and make the proper adjustments. I was told at one of the dealers here that my bike had been lowered, the guy who I bought it from didn't mention that it was lowered (not that I recall anyway). He said that by doing that it would have made the rear suspension more "squishy". Is that true? The bike does sag down quite a bit, even when someone small like myself gets on it. I never would have guessed that it might be too stiff still, definitely need to look at that.
 
There are different ways to lower a bike, one is adjusting the spring on the rear, and the other is replacing the lower link.

If you back the spring off to the point that there is no longer any preload, the spring rate becomes more progressive, very "squishy" then getting firm. You need some measure of preload for a proper spring rate throughout the travel.

If the spring has been loosened to the point where there is no preload, you need a softer spring and more preload.
 
When the dealer showed me why my bike was lowered he pointed to 2 circular silver coloured rings that were on my spring, one was right on top of the other. Would that indicate that it was backed off so that there is virtually no preload? This is like an information overload for my brain right now, lol. Trying to take it all in and make sense of it is hurting me.
 
On another thread ... I tried practically everything to get rid of the wobble. It came on a varying speeds, depending mainly on the road surface. Eventually, set the front and rear suspensions back to the original setting and had the wheels very carefully balanced. This worked! (But it still has to be re-done fairly regularly)
 
notoriouz said:
When the dealer showed me why my bike was lowered he pointed to 2 circular silver coloured rings that were on my spring, one was right on top of the other. Would that indicate that it was backed off so that there is virtually no preload? This is like an information overload for my brain right now, lol. Trying to take it all in and make sense of it is hurting me.
Click to expand...

Yes, those are the spring adjusters. They are tightened against each other like jamb nuts.

If you're as light as you are, and it's got the factory spring, that's probably part of your problem.

In the meantime, check your air pressures and rear wheel alignment. Stand far behind the bike and see if it's visibly angled one way or the other.
 
organ donor said:
On another thread ... I tried practically everything to get rid of the wobble. It came on a varying speeds, depending mainly on the road surface. Eventually, set the front and rear suspensions back to the original setting and had the wheels very carefully balanced. This worked! (But it still has to be re-done fairly regularly)
Click to expand...

That's good to know, if all else fails I will have to try this.

RDTCU said:
Yes, those are the spring adjusters. They are tightened against each other like jamb nuts.

If you're as light as you are, and it's got the factory spring, that's probably part of your problem.

In the meantime, check your air pressures and rear wheel alignment. Stand far behind the bike and see if it's visibly angled one way or the other.
Click to expand...

Thanks for the help, I'm going to try and check a few things today if the weather cooperates.
 
Hi Notorious,
This may sound silly but I think you should do a quick test before you go deeper or spend any money on that issue.
Remove your mirrors, go for a ride and see if you still get the head shake. If not... you found the cause, they are misaligned.
When I first bought my bike she came full stock and had a massive head shake starting around 130km/h.
Tried everything from tire pressure, suspension settings, body positioning but nothing really solved it.
One day I woke up and thought... damn, it can be the mirrors! I remove them and the front end wobble completely disappeared.
I'm in 'track mode' now with no mirrors at all, but after that I carefully align them and got quiet decent results.
Give it a try.
 
vmoreira said:
Hi Notorious,
This may sound silly but I think you should do a quick test before you go deeper or spend any money on that issue.
Remove your mirrors, go for a ride and see if you still get the head shake. If not... you found the cause, they are misaligned.
When I first bought my bike she came full stock and had a massive head shake starting around 130km/h.
Tried everything from tire pressure, suspension settings, body positioning but nothing really solved it.
One day I woke up and thought... damn, it can be the mirrors! I remove them and the front end wobble completely disappeared.
I'm in 'track mode' now with no mirrors at all, but after that I carefully align them and got quiet decent results.
Give it a try.
Click to expand...

Wow, so simple yet I never thought of it. I've been wanting to get rid of those huge mirrors and get a bar end mirror, this might make me do that sooner than I had imagined.

It makes sense though, with how big those mirrors are they must create some crazy drag when doing highway speeds.

Thanks for all the input, you guys have given me so much information to look into. Never expected to get so many replies with different possible solutions!
 
Ha, never considered the giant mirrors, I yanked mine within the first couple weeks and put on some inboard bar-end mirrors.
Good for a quick check, but not so easy to see directly behind me.
I always do a head check anyway.
 
RDTCU said:
Ha, never considered the giant mirrors, I yanked mine within the first couple weeks and put on some inboard bar-end mirrors.
Good for a quick check, but not so easy to see directly behind me.
I always do a head check anyway.
Click to expand...

Same here, it's too easy for me to just turn my head and check what's going on around me. Would you be willing to link me to the mirrors you bought? I'm trying to find some good bar end mirrors but most of the ones I've come across seem really cheap, cheap enough that I feel they'd get ripped off with the smallest amount of cross winds.
 
Just had to adjust my lever mounts and switches a bit to wedge the clamp between them. No big deal.
 
Loose stem head bearings will make mine wobble like a mofo. Otherwise I've had it up to 90 without issue. At that speed the knobbies feel like they are skating. :eek:
 
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