Riding instability

[ral299]

Greetings all, I'm hoping someone out there may have some ideas for me. When I get up to the 100+ speeds my bike gets pretty unstable in the front end, to the point I have to back off. At normal speeds it tends to want to steer to the left, and will do so if I release the grip on the handlebars. If cornering at high speeds it gets pretty unstable.
I have put a 17' wheel on the back, and have already been checking into if that is the problem, so I'm looking for other ideas that would cause the instability. The mechanics at the local shop seem to be out of ideas, and paying them to tinker aimlessly is too expensive.
I just had the oil and pressure taken care of in the front forks. Skipping the tires and wheels, does anyone have an idea what might be causing the instability? Swing arm, steering head, any ideas you might have will be greatly appreciated. THanks for any input,

 

[shawn kloker]

Going straight or in the turns?

 

[ral299]

normal speeds it wants to veer left. High speeds it wants to wobble out of my control. High speed corners same thing, a speed wobble starts. Lower speed cornering I feel it, but its manageable.

 

[shawn kloker]

normal speeds it wants to veer left. High speeds it wants to wobble out of my control. High speed corners same thing, a speed wobble starts. Lower speed cornering I feel it, but its manageable.

I would check your motor mounts and right side removable frame to make sure everything is tight.Possibly your neck bearings and races are bad but I think your are feeling the frame flex in turns.The best cure for it is frame braces.Solid motor mounts help but not as much as frame braces.

Did you buy this bike used and are you sure the frame is not bent?

 

[4gasem]

So you are running radials front AND rear right?:ummm:

Head bearings and check the torque on the swingarm bearings. Tire pressue is where??

I had my Max to a gps verified speed of 128 last weekend 140 on the speedo and it was like a rock...:eusa_dance:

Stock forks?

 

[ral299]

I bought it used, its a 97 with just under 30k. I was told it was never down, and I've never put it down. I'm running radials front and rear.
What should the torque be on torque be on the swing arm bearings, and is there an easy way for a very novice mechanic (me) to check the head bearings or is this shop stuff?
Tire pressure is 32 front, 37 rear, I always check them before I hit the road.
I'm planning on putting the frame braces on before this next season because of the frame flex. I like to corner fairly aggressive on it. With the braces on are the motormounts still needed?
When checking the motormounts what am I looking for? I wasn't aware that there is a removable portion of the frame on the right side, but I will look for it and check it out.

 

[4gasem]

I bought it used, its a 97 with just under 30k. I was told it was never down, and I've never put it down. I'm running radials front and rear.
What should the torque be on torque be on the swing arm bearings, and is there an easy way for a very novice mechanic (me) to check the head bearings or is this shop stuff?
Tire pressure is 32 front, 37 rear, I always check them before I hit the road.
I'm planning on putting the frame braces on before this next season because of the frame flex. I like to corner fairly aggressive on it. With the braces on are the motormounts still needed?
When checking the motormounts what am I looking for? I wasn't aware that there is a removable portion of the frame on the right side, but I will look for it and check it out.

Frame braces are the easiest and it's amazing the difference they make too... I am also running a full Race-Tech front end too.

I run 35-36psi in the front and closer to 40 in the rear but I'm a pretty heavy guy with all my gear and such...:whistlin:

I believe torque is 4ftlbs on the rear but I would check it out first. I check mine with 1200 miles on it last winter and it was loose...:surprise:

 

[shawn kloker]

Put the bike up on the centerstand and wiggle the swingarm back and forth.You will be able to tell if the swingarm or rear diff is loose.

The same with the front end,you can jack the front wheel off the ground while on the center stand.let the bars bounce down in each direction to the stops.It should hit and only a slight bounce off of the stop.You'll also feel if it is tight or loose.Races stop signed?

Its a good idea to check all the bolts to make sure nothing is coming loose.I blue loctite everything on mine.With the solid mounts things will fall off with out it.

 

[Buster Hymen]

I would check your motor mounts and right side removable frame to make sure everything is tight.Possibly your neck bearings and races are bad but I think your are feeling the frame flex in turns.The best cure for it is frame braces.Solid motor mounts help but not as much as frame braces.

Did you buy this bike used and are you sure the frame is not bent?

It sounds like improperly adjusted neck bearings to me. It may be some of the other items you've mentioned but I haven't seen those as being the problem as often as the bearings. Let me find the routine to adjust it and I will post it.
Here is a good link here, with pictures. Start with this adjustment first and let us know if that fixed the problem.
http://md.co.za/vmax/furbur.htm

 

[davidon]

Agree with Buster readjust the head bearings first. Also I think your air press is too low. I'm running 40 front and 40 rear on radials

 

[4gasem]

It sounds like improperly adjusted neck bearings to me. It may be some of the other items you've mentioned but I haven't seen those as being the problem as often as the bearings. Let me find the routine to adjust it and I will post it.
Here is a good link here, with pictures. Start with this adjustment first and let us know if that fixed the problem.
http://md.co.za/vmax/furbur.htm

Added to links page B!

Good one!:thumbs up:

 

[shawn kloker]

Agree with Buster readjust the head bearings first. Also I think your air press is too low. I'm running 40 front and 40 rear on radials

I like to run 25psi or so in the rear.Even with radials mine will smoke the tire all the time with 40psi.I drop it down to 8-10 psi at the strip.

 

[jfeagins]

My experience (and unprofessional opinion) with tank slapping is that most of it can be avoided by insuring the balance and overall condition of the rear tire. Spin balance is the best. And make sure the rear wheel is not bent even the slightest. Head bearing setup is also very important, but the gyro effect of a bad rear tire/wheel combo will amplify at high speeds to the front end.

Front tires that are out of balance tend to cause wheel hop and not as much high speed wobble, but shouldn't be overlooked either.

Again, this is only my experience over the 30+ years I've been riding.


:ummm:

 

[4gasem]

Not sure I can agree with that... I had a BRAND NEW WHEEL from U.F.BLOW and it was over 100 thou out of tolerance. It was WAY out... I had the bike to about 115 with that wheel and felt nothing...

Needless to say I don't have that wheel or any of his wheels on my bike anymore...:whistlin:

 

[xirtam22]

I'm new to the V-Max - used to sports. I'm experiencing instability over 100 all the way to 130. I had to back off at that point because it got scary.

Not tank slapping, but more of an overall waver. I did the bouce test and it is loose. Going to tighten things up according to the furbur fix - link listed earlier in this thread (thx) and retest.

I'll post the results. Any other suggestions are welcomed from a newby to upright riding. :cheers:

 

[Buster Hymen]

I'm new to the V-Max - used to sports. I'm experiencing instability over 100 all the way to 130. I had to back off at that point because it got scary.

Not tank slapping, but more of an overall waver. I did the bouce test and it is loose. Going to tighten things up according to the furbur fix - link listed earlier in this thread (thx) and retest.

I'll post the results. Any other suggestions are welcomed from a newby to upright riding. :cheers:

After the neck bearings, the best handling mod is a set of radials.

 

[gleno]

Agree with Buster readjust the head bearings first. Also I think your air press is too low. I'm running 40 front and 40 rear on radials

I've had the same problem and it was the steering head bearings being loose.

If the front tyre is low 30's psi you will amplify the shake, especially in corners.

I agree with Davidon about those tyre pressures. I'm running 40 front and 40 rear radials and the bike is much better behaved even if the ride is a little harsher.

Does anyone think to check to see if their shock absorbers are working to spec?

How would you test them?

 

[ral299]

Thanks again to everyone for their suggestions! I checked the rear for any looseness and there doesn't appear to be any. I adjusted the rear springs from their soft position to the hard position, and that seemed to make a pretty noticeable difference.
I'll adjust the tire pressure to 40 40. For the steering head bearings, to adjust those is that the same as the Furbur fix?

 

[gleno]

Thanks again to everyone for their suggestions! I checked the rear for any looseness and there doesn't appear to be any. I adjusted the rear springs from their soft position to the hard position, and that seemed to make a pretty noticeable difference.
I'll adjust the tire pressure to 40 40. For the steering head bearings, to adjust those is that the same as the Furbur fix?

Furbur Fix also re-seats the steering head bearings.