[arooni]

Hi folks;

While passing through Napa valley on Highway 29; there were some intense twisty turns. I've been riding motorcycles about one year now; and I'll confess I don't feel incredibly comfortable with them.

In any case when I was in these turns, I noticed that the bike seemed to be wobbling a bit at these low speed intense turns. I will mention that my bike is fully loaded with probably too many things. In addition, I have noticed I can duplicate the type of wobble if I'm going at a slow speed straight ahead and push hard on the side of the handlebar (it almost seems like I can get the bike to a resonant frequency where it wobbles a bit).

I guess I'm wondering what this might be, how serious it might be, and how I might deal with it?

My gut is that the bike just has too many things on it.

 

[greywolf]

My bike is harder to handle with a full luggage load because a small change in bank angle makes a large change in weight influence. It's often referred to here as being top heavy. That being said, do you have a fork brace? That makes a difference.

 

[DougInKY]

I think Greywolf meant a fork brace, not a fork brake as he put in his post.

 

[OydnaR]

can I assume you have checked for loose fasteners, most notably the steering head bearing, and tire pressure



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[arooni]

My bike is harder to handle with a full luggage load because a small change in bank angle makes a large change in weight influence. It's often referred to here as being top heavy. That being said, do you have a fork brake? That makes a difference.

I do have a fork brace; I think I should check to make sure it's tightened and installed correctly.

 

[arooni]

can I assume you have checked for loose fasteners, most notably the steering head bearing, and tire pressure

Steering head bearing was checked and tightened to spec thanks to Sprocket prior to leaving on my trip. It may be worth testing today when I look at the bike.

I check tire pressure every time I ride more than around the town miles. It was within spec.

 

[Black Lab]

Steering head bearing was checked and tightened to spec thanks to Sprocket prior to leaving on my trip. It may be worth testing today when I look at the bike.

I check tire pressure every time I ride more than around the town miles. It was within spec.

"Spec" is too loose. Your steering head bearings are too loose. Tighten them up and the symptom will go away.

 

[ozart]

I agree with BL that tire pressure spec is too loose, but not steering head bearings.

 

[Black Lab]

I agree with BL that tire pressure spec is too loose, but not steering head bearings.

Unless grossly under inflated, a "lower" tire pressure will not cause this symptom. You actually will have better traction because of the increased contact patch. But, you will also wear your tires out faster too, because of this.

Loose steering head bearings cause the symptom the rider is experiencing.

 

[arooni]

Unless grossly under inflated, a "lower" tire pressure will not cause this symptom. You actually will have better traction because of the increased contact patch. But, you will also wear your tires out faster too, because of this.

Loose steering head bearings cause the symptom the rider is experiencing.

That's definitely worth checking before I take off.

 

[tmcgee]

That's definitely worth checking before I take off.

There's only a very narrow range where they are correct, neither too loose nor too tight. My procedure was to tighten in small increments until there was no wobble at 30-40mph with my hands off the bars. No need to go tighter than that.

 

[Black Lab]

arooni, I was actually thinking of you today, and your original post. This past weekend, I attended the 38th annual, International Floatplane Fly-in, held in Greenville, Maine. Because this weekend's trip was not a "ride", I decided to do something very unconventional for me. (A story, with photos and video will be posted about this past weekend, in the near future.).

I was camping at a local campground, and watching the events happening during the fly-in, (From Thurs evening - Sunday afternoon). Because I wasn't traveling anywhere, I packed my bike up for "camping". That means, cooler, cast iron frying pan, cooking utensils...... all of the HEAVY stuff that you would usually take with you in a car, jeep, or "pop-up" trailer!

Here is what my bike looked like when I left the campground this morning in Greenville, to head the 2.5 hrs back to Mount Desert Island, where I live.

If you have followed the work that I have done on my motorcycle, you will know that I have now have tapered roller bearings installed in place of the OEM stem head bearings. (Here is how I did it: http://www.stromtrooper.com/mainten...w-replace-upgrade-steering-stem-bearings.html)

Inside that cooler I have, my tent, my sleeping bag, my clothes, my frying pan, and several other prized possessions. Likewise for the topcase as well!

I am HEAVILY packed!

But, I have no decel - wobble, nor do I have "pumping" of my front wheel in tight, fast, or slow turns. And, I can maneuver the bike as nimbly as is humanly possible, (Dirt_Dad, if you are reading this, maybe you would be kind enough to corroborate what you have witnessed with me riding my bike?)

ANY issue with "pumping" in turns, or the famous "wobble" is directly related to stem head bearings. The best remedy is to replace them with tapered roller bearings and tighten them accordingly, (What works best is to snug them up, then back off the adjusting nut no more then 1/2 turn). At the very least, tighten up the OEM bearings by NOT following the specifications that Suzuki has printed in their Service Manual.

 

[arooni]

@ Blacklab:

I wish you lived along the West Coast so I could buy you several kegs of beer and we could knock this out on my bike. I don't have powertools etc... so I would love to find someone who can assist on the way down. Seems like its worth doing (but would take a half a day huh)?

 

[greywolf]

I have properly adjusted tapered roller steering head bearings and still notice a large difference in ease of handling a bare bike compared to a loaded bike at crawling speeds. 15mph should be fast enough to make handling easy though.

 

[Black Lab]

I have properly adjusted tapered roller steering head bearings and still notice a large difference in ease of handling a bare bike compared to a loaded bike at crawling speeds. 15mph should be fast enough to make handling easy though.

It should be noted that, your bike, as well as many other rider's, choose to ride with sidecases. There is a BIG difference in handling characteristics of a bike loaded with sidecases compared to a bike loaded on its centerline axis with gear. (Which is how I pack my bike; dry bags cinched across the rear seat. All of the weight is on the centerline axis of the bike, and not "hanging out" from the centerline. This DOES make a difference!)

 

[tiller4me]

I am suprised no one has brought up suspension settings. Overloaded, under sprung, under damped can cause same symptons. Did you set your sag for your load? I haven't checked the DLV, but every other bike I have needed a stiffer spring when I added load to get the sag and travel right. Of course, me being 210 lbs doesn't help either, since most Japanese manufacturers think we all weigh 150 or so lbs.

 

[rtb]

When mine did that it was because the lower pinch bolts were loose.

 

[arooni]

I do have an aftermarket Hyperpro progressive spring on the rear and progressive springs on the front as well. Not really sure how I should adjust the preload as the least loaded setting on this spring is equivalent to the stock with max preload.

Any suggestions for how to set it? I have been riding with the preload cranked all the way up, but want to try highway 1 with a lower setting as it will lower the backend and perhpas make the bike more stable in the twisties? Especially considering the difference between stiffness of the stock spring and my Hyperpro one?

 

[greywolf]

The Science and Black Magic of Suspension Setup

 

[Sprocket]

"Spec" is too loose. Your steering head bearings are too loose. Tighten them up and the symptom will go away.

I helped arooni (David) adjust his steering head bearings shortly before he left Seattle. When we finished, they were definitely not loose--if anything, they might have been a little too snug. The service manual specifies that with the front wheel just off the ground, it should take between 200 and 500 grams of force parallel to the centerline of the bike applied at the end of the hand grip to make the front end begin to move. Our first two or three adjustments resulted in needing more than 500 grams of force, and after our final adjustment, it took just a smidge over 500 grams.

David, if you haven't already done so, I'd recommend putting the bike on the center stand and have someone push down on the back of the bike enough to elevate the front wheel off the ground. Then you can move the bars and see if the resistance is about what it was when we worked on it. A little force--but not a lot--should be needed to make the bars move. The movement should feel smooth with no perceptible hitches or bumps as you move the bars left and right. If turning is too loose or too tight or you feel unevenness in the movement, it might be that the wobble is caused by the steering head bearings.

I'm not an expert on suspension setup, so I have little to add about what may be causing the wobble. However, it doesn't seem too surprising that a heavily loaded bike with worn tires has a tendency to wobble.

A lot of people report changes in wobble behavior after changing tires. Maybe your wobble problem will go away when you have both new tires on the bike. If not, I guess tweaking the suspension is the next thing to try (assuming the steering bearing checks out OK).

I'll be interested to hear how this gets resolved.