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Old 11-07-2012, 06:23 AM   #1981
gtbensley
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Quote:
Originally Posted by DFH View Post
Is this wobble through the handlebars when decelerating & when he has one or both hands off the handlebars? Both the front & rear wheels on motorcycles have a natural resonant flutter frequency, like a supermarket trolly wheel that flaps like crazy at certain speeds. Its easy to envisage the front wheel flutter rotating about the axis of the steering head, but also the rear wheel can do the same thing rotating around the steering head, but as the distance from the steering head to the rear wheel contact point is much greater the rear wheels flutter frequency is lower. The tricky part is when the natural flutter frequency of the front wheel becomes a harmonic of the rear wheels frequency. As the mass of the rear wheel & its lever ( basically all the motorcycle from the stem rearwards) has considerably more inertia the rear wheels attempt to flutter excites the front wheel into flutter mode. All bikes do this, but the road speed at which this occurs can be modified by design. The usual option is to design this flutter harmonic point to occur at low road speeds (30 to 45 mph for those that like feudal measures) and use the rider as an organic steering damper. Coast down through this speed range on any brand new, bog stock bike with both hands off the bars & you will spot the build & decay of harmonic steering flutter

As I said before all bikes have a point of harmonic flutter, so why is this a problem for your friend now & not before?

Things that will make the flutter point more obvious include tyres worn flat in the middle from too much slabbing, adding weight to the rear of the bike especially rigid hard panniers & double especially a loaded top box, rear suspension with too much sag, too low tyre pressures.

So start with the obvious. tell him to ride with both hands on the bars... death grip not necessary.
Cast a critical eye over how much crap he is carrying on the bike... or post a piccy so we can all waggle a finger at him.
Set tyre pressures @ 36psi front 42 psi rear from cold
Set preload so the bike sags 35 mm @ the rear with rider & all luggage installed. My guess a 12 year old VFR with stock shock & spring this will be impossible, but let us know how much sag their is now.
Check condition of tyres. Never ridden on Shinkos but any tyre worn flat in the centre from slabbing will cause problems long before its at legal limits.

Good luck & get back to us with how its going.
Thank you for the response.

The wobble is there when he rides with both hands on the bars, it can be while he accelerates, holds a steady speed or starts to slow. Yes there is a lot of crap on the bike and that's what I figured was causing it initially. We removed all the gear though and it's still there.

We have already set the tire pressure to what you suggest as we'll as looking for flat spots on the tire. Sag is all the way up.....but there is still probably more like 42mm of sag.

Lose head bearing maybe? What about raising the foks 1-2mm to see if that changes anything? We will be in San Diego until Friday morning and hope to solve it by then.
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Old 11-07-2012, 11:06 AM   #1982
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Quote:
Originally Posted by gtbensley View Post
Thank you for the response.

The wobble is there when he rides with both hands on the bars, it can be while he accelerates, holds a steady speed or starts to slow. Yes there is a lot of crap on the bike and that's what I figured was causing it initially. We removed all the gear though and it's still there.

We have already set the tire pressure to what you suggest as we'll as looking for flat spots on the tire. Sag is all the way up.....but there is still probably more like 42mm of sag.

Lose head bearing maybe? What about raising the foks 1-2mm to see if that changes anything? We will be in San Diego until Friday morning and hope to solve it by then.
When I encountered similar symptoms on my '94, it was a similar situation: I was loaded for a trip when I first noticed it, but could make it happen even after unloading. Adding pre-load (stock shock) helped, as did unloading the bike. What finally resolved the problem was replacing the steering head bearings.

After removing the bearings from the bike, I re-assembled them in my hands, and could feel the slight notch in each one. While they were on the bike however, I could feel nothing but smooth operation.

As above, start with the easy stuff first, but I believe that your primary suspect should be steering-head bearings. They're cheap and easy to replace, provided you have the right tools and something to support the bike with while you've got the front end off. I've still got the special socket for the nut, and the pin-spanner wrenches; if they're required on your 2000, you're welcome to the use of them. I'd offer work-space here in Morro Bay, but I don't even have a driveway anymore.

Good luck with it, and tell us how it goes!
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Old 11-07-2012, 05:02 PM   #1983
DFH
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Quote:
Originally Posted by gtbensley View Post
Thank you for the response.

The wobble is there when he rides with both hands on the bars, it can be while he accelerates, holds a steady speed or starts to slow. Yes there is a lot of crap on the bike and that's what I figured was causing it initially. We removed all the gear though and it's still there.

We have already set the tire pressure to what you suggest as we'll as looking for flat spots on the tire. Sag is all the way up.....but there is still probably more like 42mm of sag.

Lose head bearing maybe? What about raising the foks 1-2mm to see if that changes anything? We will be in San Diego until Friday morning and hope to solve it by then.
By flat spots on the rear tyre I mean the centre of the tyre worn down flattening the profile rather than flat spots as if the tyre had been locked & skidding. Should be easy to spot. I assume that the bike has the Shinko 009's fitted front front & rear at the same time. Mismatched tyres, especially at different points of their wear life can cause these kinds of problems all by themselves.

The normal wear pattern for tyres as they age, especially with lots of slab miles is for the rear tyre to flatten off in the middle of the tread & for the front to become more pointed. The rear wear is obvious, the bike is pushed along by the engine through the rear tyre contact patch. Do some miles heavily loaded & even constant, moderate cruising speeds can wear a tyre out surprisingly quickly. The front tyre wears to a point because it does not do much work until the brakes are applied, then the tyre contact patch is mashed into the road. It is designed to flatten out at the contact point to give more grip under brakes & this flattening out wears the outside edges of the contact point much more than the centre. If a bike, as rough rule of thumb, can go from 100mph to zero in half the time it can go from zero to 100 then you can get an idea of the forces involved.

So I would consider replacing both tyres as a set before stripping the bike down & changing steering head bearings, especially as its such a labour intensive job. On the upside actually checking the steering head bearings is dead simple & should be your first step. Lob the VFR up on its centre stand (leave the luggage on so the front wheel is off the ground) and check the bearings. Turn the bars left to right, by fingertip force only. The bars should turn with a little resistance, not flop from lock to lock (bearings too loose) & without a notchy feel, especially just off centre (bearings worn & damaged, replace). Next step kneel down and grasp the bottom of the forks from the front & pull back & forward firmly (any clunking? bearings too loose). To tighten the steering head bearings leave the bike on the centre-stand. Loosen the top triple clamp allen bolts & handlebar clamps bolts on the fork tube. Loosen & back off the chromed centre bolt on the top triple clamp & slide up the triple clamp up the steering stem. Lift clear the locking washer (with tabs) & using a drift loosen the castellated locking nut. Using the drift tighten in small steps the lower castellated nut, testing the tension as described above. Once you are satisfied with the bearing tension tighten down the locking nut (lining up the notches so you can refit the locking washer tabs in the notches) using the drift, but being cautious not to tighten the lower nut in the process. Slide down the triple clamp & tighten down the centre nut firmly, then finally tighten the allen bolts clamping the fork tubes followed by the handlebar clamps.

It is my opinion (from 15,000km away I admit) that as the bike clearly changed from being OK to being a wobbly mess during the trip that something has changed in a more marked way than the gradual change that comes with stuffed head bearings. Now that you have checked their tension what next?

You have eliminated the weight of the touring luggage so cross that off my list.

Replace the tyres as a set with stock-sized quality sport-touring rubber... Tyres have a dramatic effect on the riding experience & you are touring for the fun of it so don't cheap out here.

If the wobble is still present after re-tensioning the steering head bearings & replacing the rubber then the next cab off the rank is the rear suspension. If the sag with rider & luggage with max pre-load is 42mm then the rear spring is too soft. I'll assume that with the preload at max you have adjusted the rebound damping to max as well to help control the spring. It is possible that the shock has lost its damping through aged seals, even if oil leaks are not apparent the shock could have well lost its damping due to it suddenly loosing gas pressure.

I would'nt raise the forks up in the triple clamps as what you are doing there is experimenting on ways of disguising the symptoms of a problem, not a cure.

Have fun

DFH
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Old 11-08-2012, 11:27 AM   #1984
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Battery

The battery on my 6th Gen was showing it's age in the cold weather and I started looking at new ones. Came across this and wanted to share with anyone else who may need one. http://www.st-owners.com/forums/show...S-battery-sale Can't believe how expensive these are otherwise.
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Old 11-09-2012, 03:16 AM   #1985
Ray of Sunshine
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The battery on my 6th Gen was showing it's age in the cold weather and I started looking at new ones. Came across this and wanted to share with anyone else who may need one. http://www.st-owners.com/forums/show...S-battery-sale Can't believe how expensive these are otherwise.
When the battery on my VFR went dead I went to the local NAPA got a new gel battery for AFAIR $80.00



Of course, a month later the Rectifier officially StB'd and was replaced. Twenty minute operation.
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Old 11-09-2012, 08:08 AM   #1986
AWolff
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6th Gen Passenger Backrest?

Has anyone found a source for a passenger backrest for 6th gen VFRs besides Corbin? I've checked with Sargent and it's not offered as an option, and Givi makes a topcase with backrest pad but I don't really want a topcase.

Any other source?

-AWolff
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Old 11-17-2012, 12:58 PM   #1987
rat110
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Im so pumped! Next week I'll be in a position to actually buy a vfr800

Im going on another test ride on one today. 5th Gen, Yellow with black rims.
35,000 KMS, for about $5000 Australian. Everything is expensive over here, so that price is normal.

I have test ridden about 5 different types of bike, and the Viffer just speaks to me. My wife loves the look of it and is happy for me to fork out another grand on new gear to go with it YAY!

Anyways, enough computing, I have a bike to go test ride!
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Old 11-18-2012, 01:39 PM   #1988
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Old 11-18-2012, 03:49 PM   #1989
seantx
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Very nice! Congrats sir.

I had to go check the garage after seeing that.



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Old 11-18-2012, 04:06 PM   #1990
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Quote:
Originally Posted by gtbensley View Post
It spins fine and when the front is suspended it doesn't seem to have slop.
There have been some great answers on your headshake problem. Google .headshake' and you'll find many different make and model bikes do this around 40-50mph, especially while decellerating.

I have a Honda ST1100 and the 50K+ miles I rode it, I have run 3 different front tires. The OEM tire had no headshake, Bridgestone BT023s have NO headshake, while Avon Storm and Storm ultras shake like a dog crapping a peach seed. I know of dozens of ST1100s that can not run Avon Storms on the front, doesn't maytter if the head bearings are stock or changed to tappered roller bearings.

You could have mechanical problems, but i'll bet a dollar to a doughnut that the bike doesn't like that front tire.
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Old 11-18-2012, 07:45 PM   #1991
mike884
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Been driving my new to me 94 750 around A LOT, and I'm freaking hooked! This bike is a riot, if a bit cramped. Now if I could only shove this motor into my vstrom.... honda where is my crossrunner!
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Old 11-24-2012, 04:48 PM   #1992
rat110
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I picked up a new to me 99 VFR800 in yellow on Friday night.
I freaking LOVE IT!

Ive just been taking it gentle on it as I am still getting used to a bigger bike with 3 x the power of my last one

http://i128.photobucket.com/albums/p...800/MyVFR1.jpg

http://i128.photobucket.com/albums/p...R800/MyVFR.jpg

rat110 screwed with this post 11-24-2012 at 05:01 PM
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Old 11-24-2012, 07:15 PM   #1993
yooperbikemike
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Quote:
Originally Posted by BuddingGeezer View Post
There have been some great answers on your headshake problem. Google .headshake' and you'll find many different make and model bikes do this around 40-50mph, especially while decellerating.

I have a Honda ST1100 and the 50K+ miles I rode it, I have run 3 different front tires. The OEM tire had no headshake, Bridgestone BT023s have NO headshake, while Avon Storm and Storm ultras shake like a dog crapping a peach seed. I know of dozens of ST1100s that can not run Avon Storms on the front, doesn't maytter if the head bearings are stock or changed to tappered roller bearings.

You could have mechanical problems, but i'll bet a dollar to a doughnut that the bike doesn't like that front tire.
My experience with Avons on ST11's was that they needed a shitload of air pressure, like 48 PSI, to work.
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Old 11-25-2012, 09:30 AM   #1994
rich tintera
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Quote:
Originally Posted by rat110 View Post
I picked up a new to me 99 VFR800 in yellow on Friday night.
I freaking LOVE IT!

Ive just been taking it gentle on it as I am still getting used to a bigger bike with 3 x the power of my last one

http://i128.photobucket.com/albums/p...800/MyVFR1.jpg

http://i128.photobucket.com/albums/p...R800/MyVFR.jpg
Man, that really looks minty. Congrats!
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Old 11-25-2012, 11:24 AM   #1995
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Quote:
Originally Posted by rat110 View Post
I picked up a new to me 99 VFR800 in yellow on Friday night.
I freaking LOVE IT!

Ive just been taking it gentle on it as I am still getting used to a bigger bike with 3 x the power of my last one

http://i128.photobucket.com/albums/p...800/MyVFR1.jpg

http://i128.photobucket.com/albums/p...R800/MyVFR.jpg
Mmmmmmmmm, beautiful!
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