High speed wobble??

[XS650D]

I have a 1977 XS650D .It has been totally restored from frame out,new wheels and tires,fork tubes,oil lite bushings were needed,new steering head bearing ect ect.Running Bridgestone tires,not even a 1 mil runnout on rims(balanced perfect) new shocks rear and new fork oil (10 weight) and seals.I find that bike will run super smooth up to approx 75/80 mph then i get a front end wobble and have to back off.is this an inheriated trait off this bike or model year.I have gone over ererything that i think would cause this,susp,alignment,tires,rims,its got new chain and sprockets,frame is strait,anyone.I know this bike will run over a 100mph easily but don,t feel safe now doing it.It has the strait rate springs and preload washers in to tighten things up a bit which really helped the front end in spirited driving in winding ruff roads,have preload on rear springs at half way,thx for any feed back.

 

[TwoManyXS1Bs]

Soft/ribbed front tires can do that.
Here's some threads to review:

http://www.xs650.com/forum/showthread.php?t=26963&highlight=wobble
http://www.xs650.com/forum/showthread.php?t=27912&highlight=wobble
http://www.xs650.com/forum/showthread.php?t=30941&highlight=wobble
http://www.xs650.com/forum/showthread.php?t=29362&highlight=wobble

 

[grizld1]

No, XS650D, that wobble is not something inherent to your motorcycle. My D will redline in 5th with 17/34 sprockets (yeah, the motor's been breathed on) without instability. TwoMany has given you some good advice. Here's some more.

Understand this: specifying your preload setting is meaningless. What signifies is laden sag. If you want the procedure for measuring this, Google Total Control Training, go to their site, and download their excellent "Suspension 101" handbook--it's free.

You haven't mentioned anything about what shocks you're using, how you installed and inspected the Oilite bushings in the swingarm, what steering head bearings you installed and how you adjusted and inspected steering head tension, whether or not you're using a fork brace and if so how you installed and inspected it. Check those topics as well as the links TwoMany gave you; they've been discussed.

One issue that often crops up is that the flanges on many aftermarket swingarm bushings are thicker than the flanges on OE nylon bushings. This leads to a problem. The inner bushing (tube) on the swingarm axle is designed to lock against the thrust plates in the seals and brace the frame, so that the swingarm with the outer bushings is free to rotate around the inner bushing when spec. torque is applied to the swingarm axle; in other words, the swingarm has to have some side play, and to achieve it, the inner bushing must be longer than the end-to-end width of the swingarm (I like to see between .006" and .008"). With thicker outer bushings, installers sometimes compensate by using far less than spec torque to leave the swingarm free to move. The result is flex at the swingarm pivot, which can and will cause front wheel oscillation. The best way to recover lost side play is to remove a small amount of material from the chamfered edges of the swingarm holes, allowing the outer bushings to seat more closely. The swingarm material is fairly soft, and a few strokes with a flat file is usually all that's needed. Swingarm side play specs are in the factory manual that you can download free at www.biker.net (thanks again, Jean Akers!) A good 12" caliper is your friend.

 

[gggGary]

Just saying listen and respond to what the ole' Grizzly bear sez.
Please do follow up and tell us more. Then keep us posted while you sort this out.
Oh we need to see pics, we live for the pics!

If you have never heard this before: to damp out a weave PUSH on both handle bars. This is not meant as a way to keep riding while masking a problem, but the push method works to prevent a wobble/weave from getting out of control while you slow down.
What (Bridgestone) tires are you running? How many miles on them. IMHO The retro tread styles are not so good for high speed work. If the tires have some miles on them look for cupped front tread as a possible wobble inducer. Been there, felt that.

While the 70-73 had a bit of a rep in the handling department 74 on are decent high speed performers. I have had no problems at any speed, once the bike has been sorted.

 

[XS650D]

Yhx everyone for feedback,lots to look at,glad to here this is not a trait and can be dialed out once found.FYI i am running Bridgestone Spitfire tires,they now have approx 1000 k,bike had maybe 2000 miles on od before it was totally striped and rebuilt,repainted with over $7000 cdn invested from Mikes xs and 650 central,not to mention the the many hrs that have been spent on assembling,runnin around ect.Its like a brand new bike,maybe 95 %.I have the graphics or decals of a 75 as i likes them much better,everything has been powder coated then clear coated,stainless steel spokes with new aluminum rims,had front and rear fender painted to match new tank,only thing not stock looking really is the BSA pea shooter pipes,i think they look much better,i will take some pics and post.Worth noting is this bike was purchased in NFLD in 77,i have the original bill off sale ,original owners manual and Yamaha parts book and shop manual.I purchased it from a Yamaha/Honda bike mechanic that did most off the work and was suppost to be his last project or bike but unfortunately he had an accident couldent ride anymore.Interesting story actually,i personally will be keeping this bike for a long time and maybe hand it down to my son,they just dont build them like this anymore.

 

[TwoManyXS1Bs]

New spokes and alloy rims? They may have settled-in a little and need retightening and truing check...

 

[fredintoon]

Hi 'D,
what they all said. And check the head race setting.
Too loose or too tight can cause steering wobble.
Set the bike with it's front tire just off the ground.
Adjust the headraces so the bars stay straight until you just nudge the grip then they fall to one side.
If they flop over without the nudge the races are too loose.
If they don't flop after the nudge, they are too tight.

 

[XS650D]

Can someone advise how i add a pic,thx

 

[I am Carbon]

when making a post in go advanced, scroll down to the manage attachments there you can attach a pix

 

[5twins]

I do lots of pics so find it easiest to use one of the free on-line photo sites to host them and then link to them there. As far as your problem goes, if all the suggestions so far fail, you may have to consider the possibility of an incompatible tire tread pattern. I know you have a good brand name tire and a matched set, but it could still be the cause. I'm wrestling with a similar problem myself at the moment. I've always used the Cheng Shin C906 front tire. It worked well and was compatible with any rear I'd mated it with .....

Unfortunately, they stopped making them. So, I recently mounted a matched set of Shinko 712s. They've had pretty good recommendations around here and are inexpensive, so I thought I'd give them a try. I now have a minor front end head shake at lower speeds, say in the 20 to 25 MPH range. Swapping in my spare wheel with a still good C906 eliminates it so everything is pointing at this new tire. I've tried everything I can think of - balance, different tube, wheel true & spoke tightening, new wheel bearings, steering head bearing adjust - to no avail. But the fact remains there was no head shake with the old tire on this same wheel, so none of the things I did should have needed doing anyway. So I've come to the conclusion that either the tire is bad or its tread pattern is just incompatible with the bike.

 

[XS650D]

these pics are from last summer

 

[5twins]

I notice you have what appear to be those junk $79 MikesXS rear shocks. They're stiff as a board. Too stiff rear suspension can cause a front end wobble. You might also consider adding a fork brace. They really help on these bikes.

 

[XS650D]

Yes,your correct,Mikes xs issue,yes ther junk,when i asked previous owner ,he sid they just looked rite on the bike and thats why he got them,they r stiff and weighting 150 dosent help,they r starting to give a bit.Also bike has new wheel bearings and brakes front and rear.

 

[XS650D]

My manual states to run air pressure at 25 front and 30 rear,would this cause handling problems as the tires they ran back then were probably different.If all else fails i will get a fork brace,just not crazy about the look.

 

[5twins]

Yes, it could. Modern tires are happier with more air. I run 30 to 32 front and about 35 or 36 rear. I don't find anything wrong with the look of this type of fork brace, in fact I kinda like it .....

The ATK I have is no longer made but there are similar braces from others, like this Tarozzi .....

http://www.fastfromthepast.com/25-0045

 

[grizld1]

+1 on inflation pressure, 5twins!

I use a pair of Shinko 712's on my D and they're fine at all speeds, so the problem with your front is probably due to a defective tire rather than tread pattern. One of the 712's had to be returned because the bead wouldn't seat evenly. I bought the tires at Cycle Tech, a local independent shop in Carbondale, IL, and the owner caught the defect during installation, so replacement cost nothing--one reason among many why I don't buy tires online.

The TKat fork brace is also a very nice item.

 

[lakeview]

650D, that machine is a beauty. Looks like you live north of hwy 7, where the good roads are.

 

[glennpm]

I've had three experiences with wobble.

On my Buell Ulysses, I started getting a high speed wobble with quick direction changes at highway speeds. I checked steering head bearings, although not many miles on them; tire pressures, axle bearings, etc. I found that it was a worn, not worn out REAR tire that was the culprit. I also added a steering stabilizer for the long term safety of me.

On my BMW, K100RS I started noticing wobble first at high speed passing one time and then also increasingly at around 20 plus mph. In this case it was the head bearings. Fred gave good advice above in raising the front wheel to check. For the Beemer there was a pull force provided in the manual which you could do with a fish scale. The pull is low probably around 5 or 6 pounds. The other thing to be aware of though is that since you travel most of the time with the wheel straight ahead, the bearings get beaten and Brinnel harden the races. Look out for a notchy feeling going across the center. If you notice it, its time to replace the bearings.

My third experience is when I added an articulated/leaner sidecar to my Beemer. Due to the side load and tracking I had to increase front fork pressure and damping to get rid of low speed wooble for the rig.

Hope you can sort it out.

 

[XS650D]

Thx,i wll test with more air in the spring,every bushing and bearing on bike was replaced but could have a bad one or incorrect install,i will start with the simple tests as above.That fork brace looks good,dident like the big loop style,i will look into tarozzi units,thx
Lakeview i am up in muskoka,pretty sweet to ride and snowmobile up here.The city,s nice,no bugs but u gotta ride like everyones out to get u,i enjoy it much more now.

 

[Uhlaf]

More Ontarians, is there a ride/support group for us yet?