Author Topic: Steering stability issues  (Read 4551 times)

Bill G

  • Newbie
  • *
  • Posts: 14
    • View Profile
Steering stability issues
« on: June 05, 2016, 01:12:02 AM »
I have a 2006 Grand Vista that I have owned since it was new  It has 18,000 miles on it.  Never in a wreck, but the steering has become very unstable over the last few years.  It pulls to one side, and if I take one hand off the handlebars, with one still on, it starts shimmying pretty badly.  I would not even attempt to take both hands off.  This makes me feel very hesitant to go out on the freeway any more.

Is the steering something that can be aligned on a scooter? 

-Bill

Bill G

  • Newbie
  • *
  • Posts: 14
    • View Profile
Re: Steering stability issues
« Reply #1 on: June 05, 2016, 03:10:41 AM »
Never mind, I see I asked the same question about a year ago.  Sorry, folks for the repeat.  The remove button does not seem to allow me to delete my message.

Having now gone back and re-read the post from last year, I will try to take the box off the back and see if it helps, as suggested.

Thnaks
« Last Edit: June 05, 2016, 03:12:16 AM by Bill G »

doublej

  • Newbie
  • *
  • Posts: 43
    • View Profile
Re: Steering stability issues
« Reply #2 on: June 06, 2016, 12:03:44 PM »
Check your stearing head tube bearings. Also is the brake dragging or scalloped tire tread pattern. Top box should not make that issue!

CROSSBOLT

  • Hero Member
  • *****
  • Posts: 7763
  • West Tennessee, USA
    • View Profile
Re: Steering stability issues
« Reply #3 on: June 06, 2016, 12:37:12 PM »
What brand and style of tire on the front? It can make a big difference.

Karl
Karl

Three motorcycles 1960-1977 (restored a 1955 BSA)
Agility 50
Yager 200i
Downtown 300i
Navy tech, Ships Engineer, pilot and aircraft mechanic

Bill G

  • Newbie
  • *
  • Posts: 14
    • View Profile
Re: Steering stability issues
« Reply #4 on: June 07, 2016, 05:58:07 AM »
Check your stearing head tube bearings. Also is the brake dragging or scalloped tire tread pattern. Top box should not make that issue!

Steering bearings seem to be good.  Checking with the scooter on the stand and the front elevated off the ground, it is entirely free with no binding and while I pull and push on the handlebars, there is no play at all.  No scalloped pattern on the front tire, and as far as I can tell, no real brake dragging.  Again, with the front tire off the ground, it spins fairly freely by hand, with a very slight amount of brake pad drag,  but something I would consider to be normal.   It has no wheel bearing play that I can feel or detect.  I didn't think the box being there or not would have any effect.  Just to check, though I took the GVI box off and have the same results.

Maybe I should ask a shop what they think.

@ Crossbolt:

With over 18k, of course the tires are not original, nor are they Kymco tires.  I live in a town of 35,000 and there is no Kymco dealership within 150 miles of here, so a local shop ordered the tires the last time I needed them.  Off-brand "Avon"  size is what is called for, 120/70 - 12, and I am pretty good at maintaining 40# of pressure.

pipster326

  • Sr. Member
  • ****
  • Posts: 358
    • View Profile
Re: Steering stability issues
« Reply #5 on: June 07, 2016, 07:25:10 AM »
Not sure if it would be that simple, but 40 psi sounds a little high for the tire pressure. Have you checked the sidewall for max pressure on that particular tire? Anything loose, where the handlebars bolt to the forks?


Sent from my iPad using Tapatalk

doublej

  • Newbie
  • *
  • Posts: 43
    • View Profile
Re: Steering stability issues
« Reply #6 on: June 07, 2016, 10:24:02 AM »
Lower the air pressure to stock set up. Try ride again. Are they even balanced? Try Dynabeads. Avon is a good tire, better than what Kymco installed at build.

Stig / Major Tom

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 14691
  • Rural Ohio
    • View Profile
Re: Steering stability issues
« Reply #7 on: June 07, 2016, 10:46:35 AM »
I am pretty darn certain that I have read of this issue before with this scooter.
Exactly as you describe!
As I recall. ...there was nothing found wrong with scooter.
The advice was to keep both hands on bars at all times.
40 in fronts has gotta be way over Kymco's specs for any brand tire on this scooter.
Would feel like a solid rubber hand cart tire up there!
Stig
Boston Strong
Rural Ohio

And, I'm feeling a little peculiar.

BettinANDlosing

  • Hero Member
  • *****
  • Posts: 2235
  • Carter Merz
    • View Profile
    • Columbia Scooters
Re: Steering stability issues
« Reply #8 on: June 07, 2016, 03:27:25 PM »
I find the best psi combo for freeway with the gv was 40 rear 35 front. If the tries are off balance they will shimmy the front end. Very slight defects in the tire will cause a shimmy. Order a set of Michelin power pure tires on Amazon, 120/70-12 & 140/70-12. Best tires hands down for the 12" setup. My gv I could go no hands down a large hill unless I had overly loaded the under seat storage area with heavy objects.
2002 Kymco B&W 300; MRP 78MM "300CC", Naraku cam, Yoshimura rS3 exhaust, 17g Sliders, Yellow torque spring drilled airbox, stock carb #115 main #40 pj.

2001 "Yamaha" Zuma AKA MBK Booster; MHR OverRange, Dellorto 19mm BHBG, Polini "big" intake, RS-3 Rear shock, Stock cylinder.

Bill G

  • Newbie
  • *
  • Posts: 14
    • View Profile
Re: Steering stability issues
« Reply #9 on: June 08, 2016, 04:58:44 AM »
I will let some air out and see if that helps.  I will check back in tomorrow with the results

mrbios

  • 2005 Kymco Grandvista 250cc
  • Hero Member
  • *****
  • Posts: 619
  • Just crusing along on my 2005 GV250
    • View Profile
    • My YouTube Channel
Re: Steering stability issues
« Reply #10 on: September 19, 2016, 06:57:28 AM »
I have a 2006 Grand Vista that I have owned since it was new  It has 18,000 miles on it.  ....

Is the steering something that can be aligned on a scooter? 

-Bill

Bill,

Those are good miles!  I bought my 2005 GV in 2011 with 2600 mi and now have 20K.  No signs of an accident when I bought it.  Always had the shimmy somewhere between 20 mph? to 65mph?  I have a home made throttle lock so I do take my  hands off the handlebars to adjust my glasses or gloves etc and if a shake starts I need to put at least one hand on the bars very quickly to steady it.

My last ride a '92 BMW K75S had a shimmy between ~ 45 to 55mph.  I tried different tires, and air pressure etc.  No change.  After reading an article on fork alignment I adjusted my forks by adding shims.  Once aligned the problem never returned.  I sold the bike with 64K on it.  A second problem that I was never able to solve with pulling or "drifting" to the right which required constant pressure on the left handlebar grip.

Motorcycles / Scooters often can be "aligned" by using shims and other things but it is a painstaking and laborious process involving strings and a machine if available but almost no one does it do the cost and effort. 

Steering bearings, tire brands, balancing, etc have no effect on the problem.  Also, I have worked on bikes where the steering bearings were so desperately in need of grease that they and become "indexed" but still did not wobble.

I checked the fork alignment on my GV and it was off a little bit but there is no place to insert shims like in a fork brace that most motorcycles have above the fender.  If you are worried about riding on the highway and want to solve the wobble for good it might be time to retire the GV.
PaulC

tastroman

  • Newbie
  • *
  • Posts: 23
    • View Profile
Re: Steering stability issues
« Reply #11 on: November 07, 2016, 11:03:41 PM »
 I'd also check the tightness of your rear axle nut. It can loosen and caused steering issues.

ScooterLar

  • Full Member
  • ***
  • Posts: 229
    • View Profile
Re: Steering stability issues
« Reply #12 on: November 08, 2016, 02:43:50 PM »
I have two GV's. One shakes badly when you let go of the handlebars and the other one doesn't. Both were bought used with very low miles and both had their front and rear tires replaced this summer (same brand).  I have given up trying to figure out why one does it and the other does not. I just keep both hands on the handlebars at all times. Both are equally stable on the highway.
2005 Grand Vista
2006 Vespa LX 150
2009 Grand Vista
2006 People 250
2013 Like 200
2013 Like 200 LX
2012 Genuine Buddy 170i
2009 Genuine Buddy 125

mrbios

  • 2005 Kymco Grandvista 250cc
  • Hero Member
  • *****
  • Posts: 619
  • Just crusing along on my 2005 GV250
    • View Profile
    • My YouTube Channel
Re: Steering stability issues
« Reply #13 on: January 02, 2017, 07:47:39 AM »
I have two GV's. One shakes badly when you let go of the handlebars and the other one doesn't. Both were bought used with very low miles and both had their front and rear tires replaced this summer (same brand).  I have given up trying to figure out why one does it and the other does not. I just keep both hands on the handlebars at all times. Both are equally stable on the highway.

Which year shakes the 2005 or the 2009?  Just curious.
PaulC

ScooterLar

  • Full Member
  • ***
  • Posts: 229
    • View Profile
Re: Steering stability issues
« Reply #14 on: January 02, 2017, 02:03:44 PM »
The '05 shakes.
2005 Grand Vista
2006 Vespa LX 150
2009 Grand Vista
2006 People 250
2013 Like 200
2013 Like 200 LX
2012 Genuine Buddy 170i
2009 Genuine Buddy 125

An Error Has Occurred!

Call to undefined function split()