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Discussion Starter · #1 ·
I just had a terrible experience with a high speed wobble and I am looking for the cause. I just posted a lenghty explanation of what happened on the Yahoo V8Cyclegroups web site. I know many of you bounce back and forth between sites so maybe you could read it there. I just wanted to cover both sites for as much feedback as I could get.
Thanks,
Rick
 

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Rick , I have to agree wiyh Adrian . I think it could be your alignment. That combined with the softer sidewalls would do it . I know from my experience with alignment you can't have your belt track perfectly in the center of the pulleys and have perfect alignment unless you adjust the pulleys themselves . I did the laser alignment on my bike and what a difference in handleing . My belt tracks slightly off to the outside of the pulleys but the wheels are aligned perfectly and I can run right up to 150 without even a quiver . Good luck
 

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Just in case someone doesn't have access to V8cyclesgroup.
19775 From: Rick Carnevale <[email protected]>
Date: Fri May 7, 2004 10:14am
Subject: HIGH SPEED WOBBLE!!!


OK guys, I need some help with this one. I experienced a high
speed wobble yesterday that required a laundry check, if you know
what I mean!! I have never had this problem before so I will start
at the beginning.
My bike is a 1996 SB Boss Hoss. It has had a car rear tire since
new and I never had a problem with it. It was a Bridgestone SF108.
The size was a 215/70 R15 and the speed rating was "S" which is only
rated at 112 mph. This was the factory installed tire that came with
the bike. I recently made many changes to the bike but the only
thing that I think could be causing this wobble is the rear tire that
I changed to. I now have a Uniroyal Laredo 235/70 R15 with the same
speed rating as the Bridgestone I took off. I am told that this tire
is made by Michelin and is a good tire. I am also told that Michelin
makes the best riding tire (for a car) and that maybe the sidewall is
too soft for a motorcycle application. I also replaced the front
tire with the same exact kind of tire that I had on it. A Metzeler
Marathon 880. Both tires where high speed balanced and I don't think
the problem is there either. No other changes where made to the
front end of the bike. I did change from a clutch to a single speed
auto with new style pulleys and belt but I don't think any of this
could be the problem. I plan to check the alignment of the rear
wheel to the front with a lazer line level that I just purchased but
I think I will find that to be good too. I am able to ride with no
hands and the bike tracks dead straight. Here is the other weird
thing. I can cruise the bike at 85 to 90 mph with no wobble. But if
I am accelerating with wide open throttle and I go through that speed
range, it goes into a real nasty wobble. I know for sure that the
swing arm bushings, rear shocks, and all that stuff are good because
I just had all that apart and checked everything. I even put all new
wheel bearings in both wheels. The wobble is not in the front end.
The handlebars do not shake. The whole bike seems to try to flop
from side to side. Not fun. It does not come out of the wobble by
useing the rear brakes either. I just had to hang on and let it slow
down by itself. It straightened out at around 70 mph. Everything I
have written here seems to point to the tire but I would like to hear
from others that have had some experience with this sort of thing.
Lastly the air pressure. I used to run 28 to 30 psi in the old tire
so I set this one the same. Then I read where several people said to
run around 36 psi in the rear (car) tire to PREVENT a high speed
wobble. So that is what I had in it. 36 in the rear and 46 in the
front. What is happening here??????? Puzzeled but lucky to have
not crashed!!!!!!!!!!!!!!!!

Rick
 

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Rick , I know you said you checked you neck bearings ,but once I had a Harley that had a wobble I couldn't detect until I tightened the neck bearings and the wobble diappeared.
 

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high speed wobble

Does the high speed wobble only happen with a car tire?
I changed over to a car tire and shifted about 85 and the
wobble became very violent. 'bout had to change my pants!
I never had this with the motorcycle tire, I think I am going
back to it.
 

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Discussion Starter · #6 ·
HIGH SPEED WOBBLE!

In my case I think the wobble is in the car tire that I had just put on. I had run a Bridestone car tire for 27k miles and never had a wobble. I replaced it with a Uniroyal and I think the sidewall is too soft. I only got the wobble when I was accelerating at wide open throttle through the 85 mph range. I can run it at a steady speed of 90 mph with no problem but it seems to go to **** under torque. I have another car tire on order that is a "V" rated tire. It should be fine. I will let you know in about a week or so after I get to try it out.
Rick
 

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With the roads that we have around here, it is hard to tell. I have had a couple of experiences where I thought I might need to clean my pants. I checked all of the alignments etc, and found no problems. The only thing that I came up with is 2 lbs lower air psi than I normally run. You may have something there, I never had any problem with the 230 as far as wobble. When I asked Monte about changing to a car tire on a 2000 model, he told me to stick with the 230 because of a chance of a high speed wobble. I am pretty hard headed and wanted to find out myself. I am thinking of going back to the 230, just haven't done it yet.
 

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Russell
I also have a 2000 small block and love the look of the car tire and have been thinking about changing. I keep, however, remembering the first test ride I took on a Boss which was a 99' with a car tire and how I told the dealer that unless they went to a rounded tire I wasn't buying. Sticking with the Avon.
Joe
 

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zenbiker said:
Russell
I also have a 2000 small block and love the look of the car tire and have been thinking about changing. I keep, however, remembering the first test ride I took on a Boss which was a 99' with a car tire and how I told the dealer that unless they went to a rounded tire I wasn't buying. Sticking with the Avon.
Joe
The only problem with the Avon is they WON'T hook up! If you like to putt around that is good but for the more perfomance minded the Avon pretty much sucks! There are some pretty good low profile Car tires with rounded edges but I have the MT on mine now with about 250% more contact area but the handling is suspect. No high speed problems but I have only had it to 160(still breaking in the new tranny and engine).

This bike is not made to go as fast top end as lets say the Busa not to say it won't but not with me on it! I took my Busa that fast almost everytime I rode it in to work if the traffic was clear and it is smooth as glass. My BH gets a little ugly at over 150.
 

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Dave,

I agree, the 230's are a bit weak on the traction scale, but they do awesome burnouts :lol:

A nice alternative is the 280 Metzler.....I started running one this spring and found the traction to be way better than the Avon. You can still turn it but it is controlable. Elliot and Breedlove ran Metzlers and Elliot had some wear issues.......but so far I really like the handling as we ride a lot of country 2 lane twisties......

One thing I tried to do when I redid the bike was to follow Marv Jorgensons' theory........set the bike up to run hard 0 to 100 or so......as he says, if you haven't beat them by 100, you probably aren't going to. Considering the trans power shifting issue I typically will run someone to about 130 as that is about 6000 rpm and time to shift...........so far it works.

Tim
 

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BTW, for those guys who like to run 250 or 280 tires but don't want to buy 2 new wheels, Sturgis wheel is making the Mirage in an 18" that matches the stock BH exactly. Would only have to change rear.

Tim
 

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Tim,

Thanks for the tip--have a call and email into Sturgis wheel. I hope this all works out because the MT is a 255 60 15 and the square shoulder along with the weak sidewall makes sweepers a challenge to say the least.
 

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Discussion Starter · #13 ·
High Speed Wobble

Well I thought it was the tire and I was right. I replaced that soft sidewalled Uniroyal with a Firestone Firehawk PV-41. This is a police vehicle high speed pursuit tire that is "V" rated for 150 mph. I put about 200 miles on it over last weekend and then gave it one hard blast from about 50 mph to 100 mph and there was no more wobble!! Damn good thing because I wasn't ready for another scare like the last time with the other tire! Wasn't carrying any spare shorts!!!!! Boy, am I glad that is over.

Rick
 

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GRUMPY said:
BTW, for those guys who like to run 250 or 280 tires but don't want to buy 2 new wheels, Sturgis wheel is making the Mirage in an 18" that matches the stock BH exactly. Would only have to change rear.

Tim
Tim---You got some bad information as I just hung up with Sturgis Wheel and they have never made a 18inch wheel as you described but mentioned that someone named Egotripp might. I am looking into that right now. Let me know if you find out anything. :D
 

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Dave,

Go to Boss Hoss of New England web site. Look in their accessories area and it is the last item of the 30 listed.

I was sure that Sturgis was the manufacturer of the Mirage. I had Mirage wheels on a HD a few years back and they were Sturgis made. Possibly NE Boss Hoss is having someone widen the rims, but they have to be 18" to fit the 250 or 280 (I think), but then again, I'm Norwegian :roll:

Tim
 
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