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Harmonic weave at legal hwy speeds?

Discussion in 'The Garage' started by madmax-im, Oct 1, 2019.

  1. madmax-im

    madmax-im Yamaha...Go your own way... XS650.com Supporter Top Contributor

    During the ride on Sunday at the rally . iwas riding at the posted speed limits.(55) on hwy 74. I entered a right handed sweeping turn..easy aangles nothing extreme...I was in the left lane and the bike began a harmonic weave..at first i thought i could ride through it..but it bacame worse so I immediately scrubbed off my speed to counter the weave. I suspect that road surface conditions might have had something to do with it..was very unnerving...
    Is this indicative of the 40 year old suspension? Have others experienced this?
  2. Machine

    Machine Race the wind Top Contributor

    Having also read that you did experience some dislike of the group ride location (hwy 74) and the group coordination which is a common element, as well as some personal health concerns (head ache and hbp)
    It reads to me that this initial ride time on your newly acquired XS Special II wasn’t all “in tune” yet. I think you need to experiment with fork preload, shock preload, and tire pressures to feel what works best for you. An XS is a fairly small and light motorcycle compared to say a Suzuki Bandit and your riding position and weight will affect an XS’s behavior more.
    And lol, get your mirrors situated before you find yourself hanging out in the left lane doin 55 and slowing :D
    Do 65 throttle on :cool:
    lakeview likes this.
  3. madmax-im

    madmax-im Yamaha...Go your own way... XS650.com Supporter Top Contributor

    Thanks..fwiw there was no other traffic around when this occurred and I was in the left lane. I was all alone I was not in any group and I was not following anyone... at that point..no other traffic in either direction,,The left lane looked smoother than the right lane so thats why i was in the left lane following the speed limit.
    Last edited: Oct 1, 2019
  4. 5twins

    5twins XS650 Guru Top Contributor

    Did you adjust your steering bearings? If so, you may have set them too tight.
  5. madmax-im

    madmax-im Yamaha...Go your own way... XS650.com Supporter Top Contributor

    No..the bike was ridden as i got it....I suspect that roadway conditions where this occurred were partially to blame..because i rode the same through other right and left handers at the same speeds and no weaving...
    also if I let go of the bars at 35 and slowing down the front wheel and handlebars would start to shake..not that i ride that way..but lots of times on de-accel i do relax and sit back and let go of the bars...briefly...like stretching out a bit...obviously i shouldnt let go of the bars...:geek:
  6. Gordon in nc

    Gordon in nc XS650 Addict XS650.com Supporter

    If this would have happened to me.......I'd be checking, tire pressure, steering head bearing adjustment ( thank you 5twins), all wheel bearings front and rear, wheel alignment ( I'm pretty anal about that one) spoke tension (all) and swing arm to see if all this is within specs. My guess is if it's bike related it'd be one of these items.

    Gordon in NC
    Last edited: Oct 2, 2019
    lakeview and madmax-im like this.
  7. XSLeo

    XSLeo XS650 Guru Top Contributor

    How old are the tires? When I picked up the 81 I have similar issues. As you mentioned slowing with out hands on grip it haed a front end shake. This was so bad it scared me.
    I checked all the swing arm, head bearing. tire pressure, all the usual things.
    I tires looked very good. They were just very old.
    I swapped the front wheel of my 75. No more issues. Rode like a champ.
    I them went inside and ordered new tires.
    So check the date code on the tires. If more than 5 or 6 years old they need replacement.
    Superjet, madmax-im, Mailman and 2 others like this.
  8. I had a similar issue with the Queen after she returned. The new tires(37 years and never on the road) still with the nibs were immediately renewed. The death wobble was cured.
    gggGary, madmax-im and Mailman like this.
  9. madmax-im

    madmax-im Yamaha...Go your own way... XS650.com Supporter Top Contributor

    The rear tire is close to the wear bars..I have not looked at the front tire yet... Tmrw I will take a closer look.i will be checking everything else although this bike has been very well sorted...
  10. madmax-im

    madmax-im Yamaha...Go your own way... XS650.com Supporter Top Contributor

    How do I check steering head bearings?
  11. xjwmx

    xjwmx XS650 Guru Top Contributor

    if it's new to you, check the swing arm first. use a torque wrench on the nut and there should be basically no play in the wheel in any direction with the bike on the center stand. all the above stuff i've let go at one time or another but bad original swing arm bushings definitely caused something you might describe as a "harmonic weave"
    thuban and madmax-im like this.
  12. xjwmx

    xjwmx XS650 Guru Top Contributor

    center stand, have somebody push the back wheel down and see if you can wobble the forks. if you have original ball bearings, be very careful not to overtighten. some of the suggestions for tightening them on here refer to aftermarket roller bearings
    madmax-im likes this.
  13. thuban

    thuban Horse Scratcher Top Contributor

    First and most importantly, SWING ARM. Loose swing arm will cause front end shimmy inducing counter steer, that in worst case, will progress to pull the bike out from under you. If the arm is not too loose you may be able to shift your weight, tap the brakes, roll on or off the throttle or call on the great pumpkin. If it's a full tank slap, you've got about 20 seconds to save it or get off it. So, check and double check that swing arm. That head shaking will vanish.
    lakeview and madmax-im like this.
  14. madmax-im

    madmax-im Yamaha...Go your own way... XS650.com Supporter Top Contributor

    This bike was a ground up restoration..so I seriously doubt that the steering head bearings and swing arm bushings are the originals. they should have been replaced..i will check with the PO...
  15. Gordon in nc

    Gordon in nc XS650 Addict XS650.com Supporter

    madmax-im..........IMO the bike's trying to tell you something's not right. It's up to you to listen. This isn't one of those things that an email, text or phone call to the PO is going to sort out. At this point it really doesn't matter if the steering head bearings or swing arm bushes were changed out. What you have to determine is if they are in within spec and adjusted correctly. You've mentioned you're not a mechanic.....I understand that completely because I'm not either. I respect and admire those who are....BUT......ALL the items listed are EASY to check and this site gives you the tools/instructions to do the inspections yourself. I did forget to add in my "list" tire condition/age. I've had tires that still had the nubs on them but were so old they were hard as a rock but looked like new........reading the manufacture date is easy.......just research how and then you'll know how to do it yourself ( if you don't already know).

    I'm not a mechanic and I never will be...........but I have a basic understanding how these things work and can follow instructions and take advise. IMO it's all it takes to keep these things on the road........granted people who know will shake their heads from time to time but to me motorcycle ownership is a one on one thing and I'm not too worried about what other people think about my ride as long as I'm happy with it. I "kinda" wish my bikes were pretty but I got remimded a month or so back just how much I HATE polishing side covers.......that's why my Black '78 didn't make it to the Rally......poor thing is just sitting in the shop with a sanded side cover ready for the mop but I just can't get motivated to do it.

    Hang in there.....you'll figure it out and maybe at the next Rally we'll start a grumpy ole men, who ride slow, and are socially impaired riding group....I know I'd fit right in.

    Gordon Gray in another part of NC (aka Gordon in NC)
    Last edited: Oct 3, 2019
    Machine and madmax-im like this.
  16. madmax-im

    madmax-im Yamaha...Go your own way... XS650.com Supporter Top Contributor

    Cheked the steering head with tapered roller bearings . No movement of front forks...next will be to check swingarm bushings that were upgraded to Bronze over the OEM factory plastic ones.
    I have checked the tires..they are Dunflops D404s awful tires ..has been my previous experiences with Dunflops..The rear is squared off and at the wear bars..The front tire has plenty of tread but is cupped..approx 5000 miles on these..i will replace both tires at the same time..If the swingarm bushings are good then perhaps its just those tires..that would be great..we'll know soon enough..
    Thankyou Gordon..We should get together once i get this bike sorted...we dont need any rallies to do that..;)
    TwoManyXS1Bs and peanut like this.
  17. madmax-im

    madmax-im Yamaha...Go your own way... XS650.com Supporter Top Contributor

    Tires are beyond their useful life at least 6 yrs old but could be older..confusing ..i know what the date codes look like but nothing on these tires shows just the week and year of manufacture..i am uncertain but it looks like theses tires are from 2006..i cannot confirm that but its a moot point as they are both going in the trash bin...I already know what tires i want on there but I'm not going to get into tire threads and such...so we dont need another mini tire thread going on here....
  18. If it is only a 3 digit date code then they are older then 2006. They only went to a 4 digit date code after 2000. Anything before that only had a 3 digit code with the last digit being the year in the decade. If that is the case it could be 1996 or 1986. Either way get ride of them.
  19. Machine

    Machine Race the wind Top Contributor

    D404 fronts are very inexpensive.
    There are few choices to match the D404 rear which is a good tire.
    Awareness of your tire condition right up front would have been beneficial right from the get go
  20. peanut

    peanut XS650 enthusiast & inveterate tinkerer XS650.com Supporter Top Contributor

    I will be watching your progress with much interest max as my bike also has stability issues but in windy conditions. :)

    Like you I suspect it is my tyres which are old and very hard but as I have only done around 200 dry miles this year I cannot afford the $200 cost of replacing them this year when I shall probably only ride for another 20 miles or so before putting her in the garage for the Winter.

    I was considering replacing mine with Maxxis M6103 or Maxxis M6011 but I've just seen another make that has good reviews the Avon Roadrunner AM21 not sure if either of those are available stateside though
    ps ignore the 'holier than thou ' comments which are not helpful or constructive ;):)
    Last edited: Oct 3, 2019
    madmax-im likes this.

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