Shudder/vibration

[orepicker]

When I am just starting to move and the cvt is going through it's changes, or I am moving slowly as through a parking lot, I get some vibration/shuddering from the rear of my People 250. It feels like the drive belt is catching a little as it "gears up". This happened once before and I went into the unit and cleaned and wiped around the drive belt. The problem cleared up for about a thousand miles. The repeat of the issue seems to come too soon. Anyone else have this problem?

[gregspeople250]

Yes, my 2006 People 250 does this a little bit.  If it doesn't get much worse, I'm not worried about it.

[slugrocket rob]

How many miles are on that belt? my People s200 is just starting that behavior. She has 13,000 miles on her. I was planning on a new belt the next time I find some free time.

[Portland Steve]

These CVT transmissions are not the most sophisticated systems, but they are pretty cool for what they are.
I get a shudder at times on my Super 8 150 and have done the same as you by cleaning the dust out.
I have come to the conclusion that it is the clutch that is getting glazed.  The belt flap is just a function of the clutch being fussy.
I have learned a technique here on this forum for getting the clutch to smooth out.
Hold both breaks, rev up the engine to where you feel it starting to grab and let out the breaks slowly.
This beats opening up the CVT.

[orepicker]

Good idea on using the brakes to clear out the clutch. When I had the thing opened before, the belt looked brand new. I'd even ordered another just in case. Now I have a spare.

[zombie]

Another item that helps is a torsion controller. It pre-loads the contra spring, and allows the spring to float vs. slight binding. http://www.spi-parts.com/catalogsearch/result/?q=malossi+torsion+controler

[orepicker]

Today I took my scoot out for a run. The sun was shinning and about 50 degrees. I also wanted to check out my new cycle jacket from Cycle Gear. (it was warm and toasty) I checked out the idea of running the engine against the brakes to clear up the vibration in the CVT. It worked well and ran sooooooooooooooooothly. Thanks for the tip.

[Portland Steve]

Glad that worked for you.  It is always nice when the fix is easy!

[ispud]

I have this exact problem with mine.  I changed the rollers to Dr. Pulley - that was awesome increase in acceleration, but after a week the shudder was back.  I opened things up and blew the dust out.  Everything looks great so I put it back together and it still shudders after about a week.  I had tried the brake thing from another forum with no luck - I will try it again.  I think it has something to do with the springs in the clutch.  Like I have a clue!

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[zombie]

It is caused by the "springs in the clutch" Namely the torsion control spring, or contra spring, or torque spring. Diff. names for the big spring that controls the driven pulley operation. One end of the spring sits against the clutch, and the other sits on the torque controller. These are all metal parts, and will slightly bind during their normal operation. A torsion controller is a nylon shim that sits between the clutch, and spring doing two things. It allows for the spring to operate smoothly, and it shims the spring giving a better "down shift" feeling. There are several types on the market ranging in price from 10.00-50.00 USD. If you are comfortable assembling your clutch it is an easy install... 15 minutes or so.Read up on them, and I think you will wonder why they are not pre-installed in all scoots.

[zombie]

Post script... Burning your clutch, and brake linings is never a good idea. You will wind up tempering (making the surfaces harder, and more brittle) turning them into scrap metal.

[ispud]

Anyone know of torsion controller for PS250?  I looked around some and found mostly malossi for 50 cc scooters.  A scooter tech told me that possibly softer clutch pads might help.

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[zombie]

Try SPI   http://www.spi-parts.com/   Give them a call, and mention the zuma/kymco forums for a 10% discount.
Malossi makes springs for your scoot so they should have the controller. The only "soft" clutch pads are the OEM "cork" pads. or CHEAP Chinese replacements. Stiffer springs will allow the rpms to rise above the harmonic point you have but may make the scoot feel a bit unruly for commuting purposes. Every scoot on the planet that uses a cvt will "shudder" at some rpms. You have to either tune above that point, or live with it.
The Torsion controller does 2 things for you... Smooths out the entire rpm band, and raises the "gearing" just a bit. You will hold low gear longer, and your engine braking will increase on de-accell.

[ispud]

I gave up looking after a couple days.  If anyone finds one please post.  Or if anyone has any other suggestions I am all ears.  I wrote to KymcoUSA and no reply - disappointing! 

my aprilla 500 and 200 have a bit of shudder/vibration - not too bad (compared to the ps250)  My Big Ruckus doesn't have any.

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[zombie]

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