Interstate "fishtailing" on the interstate

[Ceebass68]

Recent 1600 mile roundtrip from Richmond,Va to the Dragon and back. New-to-me I/S performed flawlessly. So happy after all the fuel system and carb rebuilding I did prior!! I did notice at times around 80mph and up on the highway, the bike would start to fishtail. All three bags were fully loaded (no more than 20lbs each) 1-up riding. At one point, in an attempt to catch up to the group, it got almost unrecoverable. Pretty scary. It was like the rear wheel was trying intermittently to step out and pass the front. Tried to duplicate after getting home with all bags/trunk empty. Kind of felt it but nowhere near as bad. Could this have been from windy conditions, the heavy load or something not right mechanically...? Anybody ever experience this?

Also, cant say enough good about this bike. She did GREAT in the twisties! She is a keeper for sure. Matter of fact, cleaned up the VTX and listed it on Craigslist today... X is a great bike, dont get me wrong, but cant keep both and given the choice...well, you know. X carried my son thru all that and he had a blast. He's in college and can't keep 2 bikes so...the X needs a new (good) home.

[Leathel]

what were your tire pressures?

[Ceebass68]

Set them at about 34psi front and 37psibrear. Just a tad over stock rec. checked them over the 4 days but they stayed consistent.

[old2soon]

M/C tires-42-44 front bout the same in the rear. Have a look at the shock bushings-should be centered on the upper one. RIDE SAFE.

[Jess from VA]

Not enough pressure.... for me (or your tire's longevity).  At least 40/40 on any valk specific bike tires (or car tire for that matter).  I always go to one or two miles under the max psi printed on the sidewall (measured cold) for all my bike specific front tires (now 41).  And I think if you add wind and bumps at speed (and a heavier than normal load), low pressures can just make any abnormality in ride worse.

Forget the manual recommendations (for the original crappy D201 Dunnys only, not every better quality tire you might run later).

Shock bushings?  Shock quality or settings (low)?  Have you closely looked at the wear you put on your tires during this trip?   Anything to see out of the ordinary?

I have had my interstate get wiggly in high gusting winds (and with maybe bumps/dips and/or a curve added) at freeway speeds several times, but never chronic.  And after back to steady straight and mostly level, smoothed right out.  High winds can make an Interstate into a bit of a sailboat for sure.  I had some excitement crossing a tall narrow bridge from VA to MD (way, way over the freighters passing beneath).

(301)

[Leathel]

Set them at about 34psi front and 37psibrear. Just a tad over stock rec. checked them over the 4 days but they stayed consistent.

I run 40 - 42, but with a full load 44

 Factory spec gives a smooth bump free ride but chews your tire and not enough with a heavy load

[Gavin_Sons]

check your shock bushings

[N8171S]

Have your steering stem bearings checked.

[Ceebass68]

Thanks guys. I will up the tire pressure and retry. I'll also check the shock bushings. Note that tire wear looks good and even so far with about 2,000 miles on new rubber.

[longrider]

The answers you received are spot on. How many miles on the bike.   After all these years we have learned a lot about the Valk.  The symptoms you describe are generally caused by Low tire pressure.  We all run them at the 40/40 mark or maybe a bit more.  Tires wil last much longer.  What brand do you have on there.  Avons are my choice.  A long time ago I stuck a set of new E3's on mine and it had similar symptoms.  Shock bushings should be replaced with VTX bushings and they last along time.  Steering head bearings need a bit of preload.  Last set I put in I set them a bit tighter than spec.  I think the IS calls for 7 ft lb and the standard 9.  Jack up the front and turn the steering side to side.  If you feel a notch right as the steering comes to center the bearings have indexed.  Replaced them or if things feel good set the preload up a bit maybe to 9 or so

[Ceebass68]

Awesome feedback guys as always!

Brand new Avons installed 200mis before trip. Funny, my "tire guy" tried to talk me out of changing as the older tires had FULL tread. BUT, they were 11 years old. My gut told me to change them and you guys here confirmed that. Stuck in the rain on twisties, I was SO thankful I had listened to you folks. My confidence level would have been WAY lower...

I'll check the steering head and rear shock bushings this weekend. Bike has 60,000 on it so, bushings are probably due...

[longrider]

Also.  With the bags loaded the shocks need to be set to either 4 or 5.  I have found the bike corners and handles better on a rather stiff setting.  I replaced my rears on my tourer with IS shocks years ago and I run them on 5.  Handles much better when I'm running with my son and his sport bike

[Ceebass68]

Also.  With the bags loaded the shocks need to be set to either 4 or 5.  I have found the bike corners and handles better on a rather stiff setting.  I replaced my rears on my tourer with IS shocks years ago and I run them on 5.  Handles much better when I'm running with my son and his sport bike

Damn...good tip. Pretty positive I'm still at stock setting of 2 I think. I imagine that would have made a huge difference.

Thanks

[old2soon]

Tire pressure-shock bushings-shock settings. On my I/S I have a lot of "stuff" in the bags and trunk just ridin one up. I keep the shocks on 4 all the time. My front tire is at 42-43 P S I and my D/S rear-A T T-is in the high 30 P S I range-bout 37-38. You have to Find YOUR sweet spot on tire P S I front and rear but I would NOT go any lower than a 4 on the shocks. These Valkyrie's we ride ain't light weights!  RIDE SAFE.

[Bagger John - #3785]

It's often said that the ills at one end of the motorcycle are caused by problems at the other.

Check steering head bearings, fork condition and wheel alignment - was the proper installation sequence followed if the front wheel has ever been removed? How are the wheel bearings?

Tires...the later-gen D206s on my I/S like 39F/41R and the Avons on my Tourer like 40F/42R. This seems to give (me) the best balance between ride, responsiveness and mileage.

[The emperor has no clothes]

As others have said. Higher tire pressure, VTX shock bushings, 4 or 5 on the settings. I've had mine at 100, 2 people, fully loaded, pulling a trailer. No sway.

[Firefighter]

My IS looks just like yours. When I first bought it, I ran the factory recommended tire pressure  and ruined both tires, (Cupped). I learned and always run at least 40 psi (both). I never exceeded 105 mph according to my GPS record, but since those days I have had that wobble at around 80 mph GPS, (85 speedo) I have replaced every bearing, rear shocks, rebuilt front forks and still had the wobble. Road conditions and wind speed and direction, and the fairing seems to play a factor as to when the wobble starts. With the fairing off I rode faster with no wobble, the bags made no difference.

I once tried to speed up to experiment and see if I could outrun the wobble and I nearly lost me and the bike!! DON'T DO THAT!!

As for the notched (indexed) neck bearings, I had that also. The bike would have to be constantly corrected at lower speeds 25 to 30 as I sorta recall, would wear me out trying to ride, constantly steering back and fort to go straight. Higher speeds it rode ok. When I checked the neck bearings, I could not find a problem until I removed the front wheel and handlebars and then WOW! felt like the steering stem had a detent, bearings fixed that.

Others here have never felt this wobble, I think some tire combinations make it more obvious, I am running a car tire and Avon at present. Hope you find your trouble and be careful, let us know.

[old2soon]

I've had mine at 120 125 M P H indicated and it Never Not once felt like it wanted to depart. Have indicated 110 115 M P H with my trailer and steady as the proverbial rock. I are anal bout tire pressure and general maint as it IS my keester in the saddle.  RIDE SAFE.

[sandy]

Avon Cobras like to be run hard. I'm on my 2nd Valk with several sets of Avons. Have always run 42F and 46R. They last a long time and don't cup. When you can afford them, replace the shocks with Progressive 444's or Works Performance shocks. You won't be disappointed in the long run. Stay with stock length at 13" for the most suspension travel.

[gordonv]

I'm sorry, but I keep on seeing people say what their tire pressure is.

It doesn't matter what your tire pressure is.

You NEED to read the side of what ever tire you have on the bike, and you want to air up, and READ what it says is the max PSI cold.

What ever that is, set it to that setting. If you don't like the ride/feel, then lower it a couple of PSI and ride it. Repeat. But be careful, it can get too soft too.

[Bighead]

I'm sorry, but I keep on seeing people say what their tire pressure is.

It doesn't matter what your tire pressure is.

You NEED to read the side of what ever tire you have on the bike, and you want to air up, and READ what it says is the max PSI cold.

What ever that is, set it to that setting. If you don't like the ride/feel, then lower it a couple of PSI and ride it. Repeat. But be careful, it can get too soft too.

It needs more pressure than recommended on tire.

[Hook#3287]

I'm going to throw in something no one else has mentioned.

Check you're rear axle nut.

You would think that isn't something that should ever be loose, but I purchased a bike that had a bad wobble.  

I checked everything on it (except the rear axle nut) and all was good.

When I went to do a rear end service, the nut was only hand tight.  

Stupid PO (or whoever was there last) and stupid me for not checking it earlier.

[old2soon]

Hook#3287 makes a very good point. The WHY of the reassembly sequence and the torque values given for the fasteners involved. Much like when I flew in the Navy I use the checklist on tear down and reassembly. And Before anyone jumps on this-I also KNOW the check lists ain't always correcttamundo-they NEED tweaking. But the Sequences involved are a Good place to start.  RIDE SAFE.

[97BLKVALK]

Make sure you have metal valve stems too!

Michael

[Ceebass68]

Make sure you have metal valve stems too!

Michael

Good tips. Axle nut is torqued properly as I replaced tires recently (removed/replaced wheels myself). Pretty sure about the front tightening sequence but, surely gonna check that. Gonna start with upping the psi and see that effect before I get too deep but, you guys have given me alot of great advice and things to check on. I'll report back.

[Chrisj CMA]

Make sure you have metal valve stems too!

Michael

Good tips. Axle nut is torqued properly as I replaced tires recently (removed/replaced wheels myself). Pretty sure about the front tightening sequence but, surely gonna check that. Gonna start with upping the psi and see that effect before I get too deep but, you guys have given me alot of great advice and things to check on. I'll report back.

When replacing the rear wheel the bolts holding the final drive on the swing arm need to be loose and shock NOT attached when you torque the axle nut. This properly aligns the final drive. After torquing the axle nut to 81ftlbs immediately tighten the four bolt for the drive to 47ftlbs. Now the alignment is locked in, you can safely attach the right side shock and any other things in any order you want.

[Alberta Patriot]

Swing-Arm Bearings maybe? 
My I/S tracks very true at high speed...no fishtail (speed wobble??) Another issue maybe...rear tire "dynamic balance"...its the same thing in a car that makes the steering wheel wiggle back and forth(shimmy) at speed...for example the tire might be heavy...say at 9 o'clock on the left and heavy at three o'clock on the right side...at speed the wheel wants to wobble side to side (fishtail) especially if there is a bit of play in the swingarm bearings.

[Bagger John - #3785]

Swing-Arm Bearings maybe? 

That tends to cause an oversteer condition - not necessarily a fishtail - but is worth checking nonetheless.

[mustang071965]

ok my 2 cents worth. had a problem like yours on the last ride from last year. catching up to my dad after a car cut me off i came around a long curve at about 80mph and got a wobble ( death wobble ) IN the rear tire. got it under control and thought well maybe its the fine Ar roads we have down here ( rain gutter tracks ) or my be my tire pressure was low. finished the ride no problems. decided well its winter time and going to due my winters Maint so i will check out the rear any way. well did every thing i had to do. every thing looked great. put it back together and come this spring we decided to ride over to greenville Ms for breakfast. well on the hwy going about 70 in a long curve theres that dange wobble back. got breakfast then we headed back on the return i noticed a ever so slight vibration in my stretch out pegs not much but there. so back at home i put the bike up on its center stand and started searching. well there was a slight right to left movement in the rear tire. well found the area where the problem lived now just had to find out how was causing it. pulled the rear tire off and checked every thing and sat there going WTF . well i knew there was some thing wrong so i pulled out my dye and sprayed the inside of the single row bearing and the double row bearing ( could not see or feel a crack ) waited 5 minutes and turned on the black light. well there she was the single row bearing inner axle race had a crack from out side to inside. pulled the bearing out gently and it was cracked clean throw with a triangle crack on the inside edge. so i called grumpy up and got a new spacer and decided to due the double row mod sense this was the 2nd single row bearing that went out on me. put every thing back together and test rode it. no more wobble or vibration. it seems that the crack in the bearing would allow the tire and rim to flex causing the vibration. not saying this is your problem just saying what happeded to me

[Savago]

@Mustang: damn, that is really bad man (lucky you to figure it out what was wrong and fixing it).

Do you happen to have snapped a photo of the cracked bearing?

[mustang071965]

Still have bearing at dad's shop will get pic of it and try to post. It had me buffalos till using the dye to find the crack

[Blackduck]

Have had that wobble on a curve.
Bad shocks .
New shocks made a very big difference.
As shocks go off you adjust to the ride and do not realise they are a problem till you get the wobble or in my case a fellow rider following me saw it wallow even though it did not feel bad.

[Hooter]

More than likely tire pressure. But something that can magnify the problem once the wobble begins as described is unbalanced packing. The two together can create problems. 

[Ceebass68]

Update (but concern not "completely resolved")... Increasing tire pressures appears to have made the situation better. Havent tried with full load (like I had when issue appeared). I will say that higher psi makes the bike more nimble and feel lighter at low speeds. It all makes sense why but, I'm definitely digging that!

[longrider]

And set the rear shocks to 5. It will make the bike feel much more nimble as well

[F-six]

Good tips. Axle nut is torqued properly as I replaced tires recently (removed/replaced wheels myself). ... I'll report back.

I wonder, did you balance the wheels correctly when you replaced the tires? An out of balance wheel will cause a wobble.

[Ceebass68]

I wonder, did you balance the wheels correctly when you replaced the tires? An out of balance wheel will cause a wobble.
[/quote]

They were done professionally. I was able to watch the guy do it so, I'm confident the balance is good.

[mustang071965]

on and off topic, can some one tell me how to post a picture to your reply. im computer dumb and cant seem to do it. i have a pic of my bearing to post for another member who requested it on my post here but can not seem to do it.

[Gavin_Sons]

on and off topic, can some one tell me how to post a picture to your reply. im computer dumb and cant seem to do it. i have a pic of my bearing to post for another member who requested it on my post here but can not seem to do it.

http://www.valkyrieforum.com/bbs/index.php/topic,85788.0.html

[mustang071965]

thanks Gavin