High speed wobble

[Biker Dash]

I have a mild wobble issue with my 03. I am nearly 100% certain that it is caused by uneven airflow over my windshield. It starts between 85-90mph, and by 120, it is at a point, while not yet tank slapping, enough that I want to back off the throttle and bring the bike back to speeds that will not send me to jail immediately. This issue never happened before I mounted a windshield, which is why I feel that is the most likely cause of my wobble issues.

At some point, I would like to have a custom mount built up that will ensure that the windshield is perfectly even in its mounting. I hope, in my case, that will correct the issue.

 

[VMax-Mike]

the giving mini Vmax windscreenand I could take my bike to 135 miles per hour with no shake.stock setup on the bike suspensionI've had the bike had a hundred fifty miles per hour but I did have a steering stabilizer at that time

 

[VMax-Mike]

if you have an odd windscreen I could see it causing it. what kind of front tire do you have and how new is it

 

[jfeagins]

Make sure you have proper air pressure in your tires.

Then, just for chits & grins, put your bike on the center stand and check the back tire for side to side run out. While up on the stand, jack the front end up and check the head bearings for proper torque, and also check the condition of your wheel bearings - front and back for any slop. Won't hurt to check the swingarm bearings too.

 

[Lotsokids]

Make sure you have proper air pressure in your tires.

Then, just for chits & grins, put your bike on the center stand and check the back tire for side to side run out. While up on the stand, jack the front end up and check the head bearings for proper torque, and also check the condition of your wheel bearings - front and back for any slop. Won't hurt to check the swingarm bearings too.

I have the mini V-Max windscreen installed. Shouldn't be an issue. I think I have a Metzler front tire, and both front and rear tires are nearly new.
All the items mentioned above are the next steps I need to take. Centerstand is not installed at the moment (removed for exhaust). But I have it, so It's possible to temporarily install it for the checks.

 

[VMax-Mike]

what metzler do you have?

 

[VMax-Mike]

I think the metzeler is only h rated 130mph. if i was you and was going over 130mph i would put a front tire that is rated for at least 149 mph. and i would have the balance on the other tire checked before i had it changed. just to know if it was out of balanced. the shinko is a good tire.

http://www.motorcycle-superstore.co...paign+Brands&gclid=CJXAjrzLo8QCFUk2gQodmakAAw

 

[Lotsokids]

Still haven't had time to install the center stand yet, but here is the situation...
Front tire air pressure was very low. Serviced front and rear with air. Still vertically unstable. Sometimes it wobbles, but not 100% of the time. The wobble comes only on hard acceleration over about 60 or 70 MPH. I still believe I have a front / rear wheel tracking issue that causes the wobble. When I let go of the bars, the bike leans immediately to the left... severely. I cannot continue without hands on the grips. I presume that a wobble comes when slight dips in the road and acceleration affect the weight on the wheels, which would cause a problem if you follow me.

I will probably need to take it to a shop so they can check the tracking / alignment or something. But I still plan to check it on the center stand first.
Thinking out loud. I hope this made sense.

 

[Traumahawk]

Check the bearings for the rear swing arm. I wonder if they were tightened up off kilter?

 

[Lotsokids]

Alright, I got the center stand installed temporarily and did a "shakedown" of the suspension. Rear swingarm is tight. Forks and front end is tight. But when I did a runout of the rear tire in second gear, I found something. Side-to-side seemed good, but there was an issue in the center tread. In the first video, you can see the line on the sidewall moving. I used a simple allen tool taped to a pole as a reference, but you can see the results.

http://vid5.photobucket.com/albums/y177/Lotsokids/V-Max/New VMax/MOV_0070_zps3iqme5sy.mp4

http://vid5.photobucket.com/albums/y177/Lotsokids/V-Max/New VMax/MOV_0072_zpszoersspb.mp4

 

[Traumahawk]

What kind of tire?

 

[Lotsokids]

What kind of tire?

Pirelli 170 / 80 - 15

 

[Lotsokids]

The wobble is back. Now worse than ever... but only occasionally. I think it is worse on windy days. The maintenance shop checked all the wheel bearings and the steering head bearings and said everything is O.K. It's sometimes so violent that my arms hurt when I get home from holding the bars so tight. It's like riding an untamed horse.

So I'm left with a few ideas:

1. The front tire. I have not changed it since I've owned the bike. But there is no "pocketing" in the tread and appears to be in good condition.

2. The vertical angle of the front tire compared to the rear. When I release the bars while riding, the bike leans immediately to the left. I suppose maybe something could be tweaked or maybe it could be adjusted by raising or lowering one of the forks in the triple tree.

3. Road condition. Hungary has TERRIBLE, uneven roads. Seems at certain dips where the bike gets light, then the full weight comes back down, the wobble returns. The wobble is minimal on the main highways or at the drag strip. But nearly daily on the roads to and from work, the wobble shows itself. Almost every time under hard acceleration over 80 MPH.

 

[jfeagins]

The wobble is back. Now worse than ever... but only occasionally. I think it is worse on windy days. The maintenance shop checked all the wheel bearings and the steering head bearings and said everything is O.K. It's sometimes so violent that my arms hurt when I get home from holding the bars so tight. It's like riding an untamed horse.

So I'm left with a few ideas:

1. The front tire. I have not changed it since I've owned the bike. But there is no "pocketing" in the tread and appears to be in good condition.

2. The vertical angle of the front tire compared to the rear. When I release the bars while riding, the bike leans immediately to the left. I suppose maybe something could be tweaked or maybe it could be adjusted by raising or lowering one of the forks in the triple tree.

3. Road condition. Hungary has TERRIBLE, uneven roads. Seems at certain dips where the bike gets light, then the full weight comes back down, the wobble returns. The wobble is minimal on the main highways or at the drag strip. But nearly daily on the roads to and from work, the wobble shows itself. Almost every time under hard acceleration over 80 MPH.

Here's another possibility: How is your BACK TIRE looking? If you have a center stand, put the bike on it, start it up and let it idle. Check for side to side run out in the tire. My OEM dunlops were traditionally bad about this. I'd develop the wobble, change to new tread, and all would be OK again, at least for another 1500-1800 miles before the rear tread would again become a bit out of sorts from side to side.

 

[[email protected]]

. When I release the bars while riding, the bike leans immediately to the left. I suppose maybe something could be tweaked or maybe it could be adjusted by raising or lowering one of the forks in the triple tree.

I think the bike going left is normal on a vmax with stock wheels and swingarm. I used to notice the same thing and I've seen a few others mention it here. Maybe because the rear wheel is offset to the right meaning more of the weight is hanging off the left... I don't know the reason but have experienced this myself.

I could change my seat position to correct but I didn't feel centered on the bike. After switching to a new rear wheel and swingarm, both with custom offset to help center the wheel, I now longer feel the bike wants to go left with hands off the bars. Maybe its just my brain and body trying to justify the expense :confused2:

I wouldn't suggest altering your fork height in the trees. That will cause issues. There is a whole train of thought on limiting "stiction" (static friction) in the suspension components. Altering fork heights would have a huge negative effect on stiction.

Head bearing adjustment, tires, and swingarm bearing adjustment are the usual suspects.

 

[Dorney]

I think the bike going left is normal on a vmax with stock wheels and swingarm. I used to notice the same thing and I've seen a few others mention it here. Maybe because the rear wheel is offset to the right meaning more of the weight is hanging off the left... I don't know the reason but have experienced this myself.

I could change my seat position to correct but I didn't feel centered on the bike. After switching to a new rear wheel and swingarm, both with custom offset to help center the wheel, I now longer feel the bike wants to go left with hands off the bars. Maybe its just my brain and body trying to justify the expense :confused2:

I wouldn't suggest altering your fork height in the trees. That will cause issues. There is a whole train of thought on limiting "stiction" (static friction) in the suspension components. Altering fork heights would have a huge negative effect on stiction.

Head bearing adjustment, tires, and swingarm bearing adjustment are the usual suspects.

My bike has stock wheels & swing arm & tracks straight with hands off bars.

Dave

 

[fastestz1]

you really should check the rear wheel/bearings,rear tire and most
important swingarm bearings,you would be amazed how much the rear
of any bike effects the handling

 

[Lotsokids]

Here's another possibility: How is your BACK TIRE looking? If you have a center stand, put the bike on it, start it up and let it idle. Check for side to side run out in the tire.

Yes, I checked the runout (I think the video is posted in this topic earlier somewhere). There was a very slight deformation in the sidewall. Rear tire was worn, so I replaced it recently.

It's just very strange. One day with same riding style, there may be no wobble. The next day I'm looking for a seatbelt to stay on it.

The only consistency is HARD accelleration, over about 80 MPH, and it shows up, and my bike wants to kick me off.

 

[Steffi]

Wheels out of balance? Lost a weight maybe?

 

[sdt354]

A visual inspection of the head bearings/races is what I'd check. I pack & adjust the bearings yearly for that reason. It gives me piece of mind when up in three digit land, where I don't like surprises. A deep groove in the race will let you adjust the pre-load and pass the bounce test. But the bike can & will shake like mad anyway. Like Dorney stated, a stock set up bike should not head shake.
Steve-o