KymcoForum.com
Scooters - 125 to 300 => Grandvista 250 => Topic started by: MaryK on April 21, 2014, 08:58:56 PM
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My GV 250 seems to be shuddering in the 30 to 40 MPH range.
I just put new tires on and had them balanced to be sure about them. Tires changed becasue of cracks in old tires.
The shuddering seems worse when the scooter is cold (start of riding) and seems to go away under strong acceleration.
I'm wondering if it could be a belt problem.... maybe cleaning is needed. Scooter is 2009 model with 4500 miles.
I plan to have my DH check the belt later this week. I read the forum about measuring the width of the belt and looking for
nicks and cracks. Any other advice ?
Thanks,
Scoot safely,
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Way too many maybes at this point.
Try to eliminate a few basics... On flat ground hold the front brake LOCKED, and try moving the bike froward, and backward with some real force. Quick strong snatches. What you are looking for is an play in the steering tube. Maybe you will feel a deflection or shifting of the bars.
Next on the center stand hold the wheels (one at a time) top, and bottom and try to wiggle them. You are looking for either worn rear gear case bearings or worn front axle bearings. Again strong quick jiggling will show up as play or clicking.
While still on the center stand try to "twist" the engine. There is ONE center bolt or pivot bolt thru the frame, and front of the engine. The bushings that isolate the engine from the frame are prone to wear, and will feel like a shudder under certain conditions. The whole assembly is kinda heavy so some creative angles, and real force is needed. Similar test for the rear shocks. Try to move the mounting points to see if a bushing is worn. with the bike flat on the tires you can try to lift the rear body, and see if you feel some odd movement or clunking from the shocks.
Most odd shudders happen in the suspension. Some come from the clutch slipping, and some come from worn variator parts. It never really comes from the belt unless it is about to come apart, and that will be obvious once you open the case.
If you still need help after checking these things there are a lots of people here to walk you thru the CVT parts, and how to improve the "feel" of the bike. DeGlazing the clutch bell w/ emery paper/changing worn clutch springs ect.. Rollers that have worn flat spots are another culprit, and fairly easy to replace.
Try the punch list for peace of mind... It may be something there.
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My shudder / judder was only at pulling away from a stop. I sanded the glaze from the clutch pad faces, replaced the belt and rollers - and the pull away is as smooth as new now. I think it was the clutch glaze.
But an issue once underway to 30MPH does not seem to jive with my fix.
But Zombie has been into more scooter guts than I have been into donut boxes - and this is my 1st scooter.
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You're right about the clutch mainly effecting take off, and it's anyone call on the scoot/doughnut thing. Vegas odds are even! ;D
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Mary:
The take off shudder will fix itself; you have a bit rust on the inner clutch bell, once worn off (after "use" of the scooter) it will be smooth.
Stig: you have a shudder at 30-40 mph? I had a weird thig, the center stand rubbber bumper was worn and caused a vibration I could not figure out for a while. Check your center-stand-bumper and bumper plate, and also re-tighten ALL bolts of the exhaust side with axle mount plate. Those bolts like to come loose under certain conditions.
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Thanks for the ideas and have printed out all of the ideas.
I'll get my DH on it tomorrow (his day off).
I appreciate the detailed list from Zombie .
I'll let you know what we find out.
scoot safely
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;)
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Mary,
if it is a take-off shudder it is the inner clutch housing/friction surface rust. Quick fix: hold the rear break firm and give it gas e.g. 1/4 throttle for 10 seconds so the clutch engages. After that, then try taking off normally and see if the shudder is gone; if not repeat above procedure. It WILL go away, may take more than one or two attempts.
Shudders above take off speed is usually something loose or misaligned. You installed new tires? Hopefully all has been put properly back in place on the suspension, and as I said, check for loose bolts.
Eric
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"My GV 250 seems to be shuddering in the 30 to 40 MPH range."
Hi Windwheeler. I've seen lots of fellas post the fix for "take off shudder" here in the past. You are right... It does fix that problem. I never like to drag a clutch so to speak but it is a good way to verify if the bell is glazed.
It might take 2 sets of eyes, and hands to get together, and give the bike a thrice over. Sometimes a foot long pry bar between mounting points will help a great deal.
Hammers, Chisels, & Striking Tools | Pry Bars | Bent End Pry Bar, 12" | B640977 - GlobalIndustrial.com
http://www.globalindustrial.com/p/tools/Hammers1/pry-bars/bent-end-pry-bar-12?infoParam.campaignId=T9F&gclid=CK2Igcm19b0CFUtk7AodRHAAYg (http://www.globalindustrial.com/p/tools/Hammers1/pry-bars/bent-end-pry-bar-12?infoParam.campaignId=T9F&gclid=CK2Igcm19b0CFUtk7AodRHAAYg)
If it doesn't help w/ the bike they are still handy.
It's Not About The Nail (http://www.youtube.com/watch?v=-4EDhdAHrOg#ws)
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Ms. MaryK: What did you/your DH find out? Is it resolved?