KymcoForum.com

Scooters - 125 to 300 => Xciting 250 => Topic started by: szabgab on April 19, 2018, 10:17:16 PM

Title: Variator chatter
Post by: szabgab on April 19, 2018, 10:17:16 PM
Dear all, finally I have gone round to replace the belt and the rollers, upon disassembly I have discovered, both the belt and the rollers are still OK, actually the belt I have measured in-situ completely wrong, and it is barely worn. Anyway, I have cleaned everything, sanded the clutch pads and the bell, cleaned the variator housing, ramps, replaced the rollers, put on the new (Xciting 250i spec) Mitsuboshi belt I have bought, everything is nice and cleaned. The clutch was catching on, chattering away and spinning the wheel ever so slightly before, but now this constant horrible chatter is coming from the variator side at idle completely overshadowing the mellow clutch chatter (that is still there). Also once the engine spins down from acceleration, the chatter gets rather loud for a second it to settle to this constant machine-gun fire mode. What did I do wrong?? Followed everything by the book, put the weights in the correct way, torqued everything to spec, even have taken the shebang apart three times since, trying to make sure, everything is spotless, etc. The belt is spinning the right direction.

I have made a video, sorry it being lousy, but my trouble is clearly audible, the chatter actually consists of three different layers, one is the (now) faint clutch chatter, some metallic noise and the loud chatter.

https://www.youtube.com/watch?v=z2KqyHLL-Hg (https://www.youtube.com/watch?v=z2KqyHLL-Hg)

Any ideas?

Thanks folks!

Gab
Title: Re: Variator chatter
Post by: CROSSBOLT on April 19, 2018, 10:30:03 PM
Hey, how are you? Good to hear from you! Yeah, I have an idea what may be your cause. De dee has a method of making sure the belt does not interfere with the front variation seating properly. I have a different method that does the same thing. His method does not require the rear pulley to be removed but takes patience and must be done in a sequence. What I think happened is the front nut was tightened against the belt and the pulley halves were not touching in the center. When the CVT started working the front pulley parts were loose!
Title: Re: Variator chatter
Post by: szabgab on April 19, 2018, 10:41:01 PM
Hey, how are you? Good to hear from you! Yeah, I have an idea what may be your cause. De dee has a method of making sure the belt does not interfere with the front variation seating properly. I have a different method that does the same thing. His method does not require the rear pulley to be removed but takes patience and must be done in a sequence. What I think happened is the front nut was tightened against the belt and the pulley halves were not touching in the center. When the CVT started working the front pulley parts were loose!

Hey Karl! So nice of you to try to help with all my bloody ailments with this bike. Since we last spoke, the electrics were fried, well basically the battery died every week or so, first I thought it is the cold, turned out to be the alternator cables, where they escape the case were somewhat eaten away from engine movement, one broke of completely. Temporarily I have fixed it with soldering the cable back in (I could just about pull out a piece of the broken cable from the case with some long nose pliers) and RTV'd the hell out of the whole assembly for now (as the other yellow strands started to disintegrate badly). Eventually I will have the to take the alternator cover off and solder on some new cables, but I want to ride and not to f... around with this bike.

Belt wise - I had the same idea, but what I did was to losen the clutch side to the point, the belt was basically hanging between the rear and front pulleys, after that I have made sure, the variator pulley sides are actually touching rather than sitting on the sides of the belt. I still could be wrong, but after running the bike shortly I have tried to torque the variator nut again to make sure it is nice and snug, and it was. But please share your way of doing it, I'm known to be an idiot who tosses up a basic step, like forgetting to put back spacing washers and the likes :)))) What I did not try to put the variator pulleys on with the belt at first, torque it down and put the clutch side on. What I did instead was to put both sides on, loosening the clutch side, torquing the variator side, torquing the clutch side.

With my old Honda I nearly butchered a clutch, because the nut did not give (I am sorry to say, I sold it like that). I should have done it then, but I have acquired an impact wrench only now... Well at least I can take the variator apart as many times as I want :))))
Title: Re: Variator chatter
Post by: CROSSBOLT on April 20, 2018, 12:11:12 AM
This is one way:
Half an inch is too little! That belt needs to have about 1.5 inch of pulley face showing. It is tough but the last time I went through this I had the back pulley off the gearbox, laying on a stout, flat board. Then with a stout bar like a breaker handle or a 3/4 × 1 1/2" stick push the belt into the sheave, hold some pressure with one hand then pinch the belt with the other. Use a string or cable tie where you are pinching the belt to save what you have then do it again until the belt top is about halfway into the pulley. Tie the pinch and put the rear pulley on the bike with the left belt loop around the front shaft. Put the front pulley together with the loads of slack and clearance you worked so hard to get. This way the front pieces will properly bottom out when you torque the nut. Whew! I'm tired just talking about it!

Go to my profile, click "show posts," go to post #73 on page 5, go to that topic and near the bottom there will be EXCELLENT pictures by Snorvey. His photos show the procedure in sequence.
Title: Re: Variator chatter
Post by: szabgab on April 20, 2018, 12:32:40 AM
Oh,  OK,  I will try that method.  BTW,  how much free movement shoulf be on the shafts?  I can most definitely move the clutch side (wheel)  shaft an inch or so side to side without movement in the wheel but also the variator shaft,  which is strange,  as I would have thought,  there should be absolutely no slack,  whatsoever...  Thanks!!
Title: Re: Variator chatter
Post by: CROSSBOLT on April 20, 2018, 01:00:45 PM
There is a LOT of gear backlash in that final drive! It is like a slack chain on a motorcycle. I am assuming the 250 is like the Agility, Yager, DT and People GTi300.
Title: Re: Variator chatter
Post by: szabgab on April 20, 2018, 03:38:20 PM
There is a LOT of gear backlash in that final drive! It is like a slack chain on a motorcycle. I am assuming the 250 is like the Agility, Yager, DT and People GTi300.

Karl, that"s good to know. I guess the engine and final drive will be most likely the same as other 250 and 300cc Kymco engines, basically a revamped Helix power plant...

What about the front shaft? I turned the engine around grabbing the front pulley, and it was relatively easy to turn (the two cylinder 400cc Honda I had was really hard to turn over by hand, but again the generator was bolted to the end of the crankshaft without any reduction, gears, etc) also I could detect free play in it of a half an inch or so...
Title: Re: Variator chatter
Post by: CROSSBOLT on April 20, 2018, 09:24:23 PM
I don't think there should be ANY freely in the front pulley. On the DT the front pulley halves are splined to the crank extention and the Agility 50 was the same. 250 must be the same. Find out if the splines are worn. I hope the extention is OK.
Title: Re: Variator chatter
Post by: szabgab on April 21, 2018, 10:02:56 AM
I don't think there should be ANY freely in the front pulley. On the DT the front pulley halves are splined to the crank extention and the Agility 50 was the same. 250 must be the same. Find out if the splines are worn. I hope the extention is OK.

OH, OK,  that's what I feared...  I will check again,  if it is free play,  or just the crank moves too easily,  but probably now is the time,  to count my loss and sell the bike before it completely falls apart...
Title: Re: Variator chatter
Post by: szabgab on April 24, 2018, 07:47:48 PM
OK,  I have done,  what Karl suggested and mad sure,  the belt is as slack as possible before tightening stuff,  it did not help.  What I have noticed though,  that the crank side of the pulleys do not re-engage as quickly as the clutch side,  making the belt rather slack for a far bit,  which most likely causes the noise upon decel.  I have taken the pulley apart,  and everything seems to be cool,  the rollers are brand new,  but I guess something is somewhat sticky.  The metal shafty thing inside the pulley and it's sleeve look to be fine,  although I didn't measure clearances,  don't ask me why.  So what else? Maybe sliders? The back plate of the roller assembly feels to be loose,  eg having a slight side-to-side movement and I can most definitely crook the plate to the point it binds on the posts.  I'm not sure if this is a good enough test,  as the pulley doing some 2-3000RPMs will behave differently. 

I have done an another video,  if that explains it better :)

https://youtu.be/sELezdWr0GU

Thanks!

Title: Re: Variator chatter
Post by: xsel777 on April 24, 2018, 08:38:08 PM
Perhaps put the old belt back, as that one seems to have a lot of slap. Possibly the edge angle is wrong or it is too long.

Sent from my Mi Max using Tapatalk

Title: Re: Variator chatter
Post by: Stig / Major Tom on April 24, 2018, 08:39:53 PM
Also, please check out CVT belt problems on youtube.
Watching the video it looks like belt slap to me, which is a common problem with scooters.
Belt is touching (slapping) at mid-point of its travel, either above or below, inside the CVT area -- especially prevalent on decel, or over-running, when you roll of the throttle.

Most of the comments on this issue center on improper belt length. A slightly too long belt will have enough slack on decel to flail out and touch. Look for marks on case or on upper side of belt. If you see nothing.....then I can add nothing more.  (have seen people put some white chalk on case above and below the center of belt.....then look to see if it is disturbed after running scooter)

Stig
Title: Re: Variator chatter
Post by: szabgab on April 24, 2018, 09:00:41 PM
Hi,  this is the old belt..  I had the same thought,  maybe a too long belt,  so I switched back to the old one.  Because it did the same,  I videod it and posted here,  as I have ran out of options.  I have cleaned all the old gunk from the ramps,  sliders etc,  could it be,  that the rubbish was cushioning the problem,  like a worn slider? BTW there are no marks on the case as yet,  before me venturing in to clean stuff it was good :( And the clutch chatter didn't go away either,  although the shoe springs are good,  the bell is rust free and the shoe pads are all within spec...
Title: Re: Variator chatter
Post by: Stig / Major Tom on April 24, 2018, 10:09:14 PM
Eliminating clutch chatter seems to be more art than science, sometimes.
But a different pull-away technique can help. Some scoots hate a gentle take off....preferring a crisp fist full of throttle to quickly lock up the clutch and minimize slippage ( which causes glazing and chatter)
Stig
Title: Re: Variator chatter
Post by: CROSSBOLT on April 24, 2018, 10:26:18 PM
Video is good! Sounds good! But belt action seems a little strange. Just to be sure, measure outside belt length and width. Actually, belt width at several positions around circumference. 5 positions should tell you if is the same for the length. Measure both belts to see what, if any differences. Then the biggie: what should be in there? When I said strange action I meant the front seems to change effective diameter but the rear seems hardly to move.
Title: Re: Variator chatter
Post by: szabgab on April 25, 2018, 10:36:17 AM
Video is good! Sounds good! But belt action seems a little strange. Just to be sure, measure outside belt length and width. Actually, belt width at several positions around circumference. 5 positions should tell you if is the same for the length. Measure both belts to see what, if any differences. Then the biggie: what should be in there? When I said strange action I meant the front seems to change effective diameter but the rear seems hardly to move.

I have measured the belt like you said,  everything is well within spec.  You are right about the circumference issue,  but it is the crank side,  that is loose,  if I kill the engine at high throttle,  the clutch side is snug, but the crank side pullwwis looae,  it is very easy to move the belt around there (whilst the clutch is holding everything together nice and tight)

Stig -  the chatter disappeares once the clutch engages,  the chatter reappears at idle. 
Title: Re: Variator chatter
Post by: Stig / Major Tom on April 25, 2018, 12:06:53 PM
Has a washer been incorrectly placed between the two front pulleys? Because belt looks too loose in video, so I still think that is belt slap. Really sounds like belt slap in closed CVT cover video.
Worn pulley faces, faces too far apart...? if not belt too long, then some other csuse for loose, slapping belt.

Stig
Title: Re: Variator chatter
Post by: szabgab on April 25, 2018, 02:33:15 PM
Has a washer been incorrectly placed between the two front pulleys? Because belt looks too loose in video, so I still think that is belt slap. Really sounds like belt slap in closed CVT cover video.
Worn pulley faces, faces too far apart...? if not belt too long, then some other csuse for loose, slapping belt.

Stig

No,  I have actually thought,  I might be missing one,  but looking at the parts diagram,  there are no washers,  only underneath the nuts,  also the two sides are not interchangeable either,  as the thread is m12 on one side,  m14 on the other
Title: Re: Variator chatter
Post by: de dee on April 25, 2018, 04:13:27 PM
  Could it be that the big clutch spring has gone soft, ????  allowing the belt to flop and change torque on the variator on and off,  ????
Title: Re: Variator chatter
Post by: szabgab on April 25, 2018, 04:53:32 PM
  Could it be that the big clutch spring has gone soft, ????  allowing the belt to flop and change torque on the variator on and off,  ????

Everything's a bloody possibility with this sodding bike of mine :)  Although I still think,  it is the other side,  that is not engaging quickly enough,  as you let of the throttle,  clutch side changes,  crank side remains open,  belt flops around for 10-15 secs and eventually evens out,  changing rpm of the engine and quiteing down...  Acceleration is fine,  but that's controlled by the centrifugal force and not by the belt forcing the pullet back to it's place
Title: Re: Variator chatter
Post by: CROSSBOLT on April 25, 2018, 06:04:25 PM
AH-HAH! That is like saying the front pulley half does not slide too well! The rear movable pulley half is positioned by spring pressure totally independent of rpm. The belt position on the rear is determined by spring pressure AND the front pulley. Do you have any lube at all on that sleeve up front? Some guys use dry lube and others like me use an extremely thin coat of moly-disulfide grease.
Title: Re: Variator chatter
Post by: szabgab on April 25, 2018, 07:07:53 PM
AH-HAH! That is like saying the front pulley half does not slide too well! The rear movable pulley half is positioned by spring pressure totally independent of rpm. The belt position on the rear is determined by spring pressure AND the front pulley. Do you have any lube at all on that sleeve up front? Some guys use dry lube and others like me use an extremely thin coat of moly-disulfide grease.

I did lube the sleeve very very sparingly with lithium based bearing grease,  also the ramps,  the sliders slide on,  again just a smitten.  That did alleviate the problem a bit,  but it is basically the same
Title: Re: Variator chatter
Post by: CROSSBOLT on April 25, 2018, 08:48:01 PM
Well, sumpthin' ain't movin'  ! Actually, lubing the rollers and ramps may not be such a good idea but that is the least of your worries. Could you do another video only show both front and rear pulleys at the same time as the speed is varied?
Title: Re: Variator chatter
Post by: szabgab on April 26, 2018, 09:17:02 PM
Well, sumpthin' ain't movin'  ! Actually, lubing the rollers and ramps may not be such a good idea but that is the least of your worries. Could you do another video only show both front and rear pulleys at the same time as the speed is varied?

Karl,  sorry,  I explained things wrongly,  I did not lube the ramps underneath the rollers,  but the rails the sliders move on.  I will do an another video soon,  but I'm away again for a few days,  work is taking up so much precious time :)))  Also the clutch chatter has gone worse,  since I cleaned the pads and sprayrd brake cleaner inside clutch body,  probably taking a shortcut I might have de-lubed vital parts :(
Title: Re: Variator chatter
Post by: CROSSBOLT on April 27, 2018, 12:47:10 AM
Work does intrude! Being retired, I would not understand! Work if you must, we will wait....not willingly...but will wait....
Title: Re: Variator chatter
Post by: szabgab on April 27, 2018, 06:18:00 PM
OK,  so I've managed to do a video of the two sides before going away...  Here it is https://m.youtube.com/watch?v=jKpFyyyAIh8
Title: Re: Variator chatter
Post by: CROSSBOLT on April 27, 2018, 06:37:00 PM
Alright! That looks pretty good. Any of the rest of you see something out of place?
Title: Re: Variator chatter
Post by: Stig / Major Tom on April 27, 2018, 06:45:17 PM
OK, I'd do this:
Remove the belt. Snug both front and rear nuts, a little.
Is there any play up/down/fore/aft in the front assembly, or in the rear?

Front shaft bearing good?......Rear shaft bearing or bearings in clutch good?

If I didn't find movement in those shafts or assemblies, I'd look at the rollers and if they are correct size and in good health (NO lube in there!) relax....it is belt slap caused by the belt.

If I really couldn't live with the belt slap, I'd try a 2nd stock Kymco belt. If that didn't help, I'd install a new clutch. @$100 for my LIKE200i, fully assembled.

Stig
Title: Re: Variator chatter
Post by: szabgab on April 27, 2018, 08:53:29 PM
OK, I'd do this:
Remove the belt. Snug both front and rear nuts, a little.
Is there any play up/down/fore/aft in the front assembly, or in the rear?

Front shaft bearing good?......Rear shaft bearing or bearings in clutch good?

If I didn't find movement in those shafts or assemblies, I'd look at the rollers and if they are correct size and in good health (NO lube in there!) relax....it is belt slap caused by the belt.

If I really couldn't live with the belt slap, I'd try a 2nd stock Kymco belt. If that didn't help, I'd install a new clutch. @$100 for my LIKE200i, fully assembled.

Stig

Stig - there is some play in the front shaft, without the pulleys installed I can pull it out and push back a little, probably 1/10th of an inch or so. The rear is fine. The clutch installed, there is a definite play rolling the bell over, but as Karl mentioned before, that is absolutely normal. The rollers are OEM stock 23*18mm / 20gr rollers, brand new, installed not 50 miles ago.  I did not lube anything in the rollers area, but the inner sleeve I have cleaned today of the lithium grease I put in the other day and used some moly lube, as Karl suggested. I aslo greased the needle bearing of the clutch, it is fine, turn around without any hiccups, so is the front bearing. Funnily enough with all this hassle I start to be back at ground zero - meaning just before I touched anything in there. The clutch chatter is not much pronounced (but audible) and the front pulley belt slap is much reduced to the decel stage of a couple of seconds. I do suspect the clutch assemby, it does not close properly sometimes, and I have to twist the pulley faces in order to get them apart at the beginning stage, but then I can push them apart by a simple pushing motion, rather than the twisting. I do not have the special clutch holidng tool, or the special narrow spanner for the thin nut, I guess, I could get by with an impact tool, but I'm somewhat afraid to take that bit apart and making matters worse (that huge spring looks to be a nightmare to hold, whilst installing the thin nut without the special tool) Anybody has got a handy tip, how to diy the thing?

Oh btw, I forgot to mention, on one of the previous occasions we spoke about the clunk if the front and how soft the dampening is. Well, I have added some 0.5dl of 10W fork oil to the forks, and it changed the whole mushy crap, that was my front to a hard, but very responsive feeling. The oil smelled in there rather gross, but I do not have a large quantity of fork oil at the moment, so replacing the old stuff will have to come later.
Title: Re: Variator chatter
Post by: juancuesta on May 01, 2018, 08:42:47 AM
I've owne an xciting for about two years. I can tell you that I heard those sounds and others. I beleive is quite common. I wouldnt worry about it too much.
Title: Re: Variator chatter
Post by: Stig / Major Tom on May 01, 2018, 11:13:19 AM
There are youtube videos on removing the big, thin, clutch nut.....and on compressing spring with your feet while threading it on again. Uses a large crescent wrench.
No impact tool needed.
Stig
Title: Re: Variator chatter
Post by: szabgab on May 01, 2018, 10:14:08 PM
There are youtube videos on removing the big, thin, clutch nut.....and on compressing spring with your feet while threading it on again. Uses a large crescent wrench.
No impact tool needed.
Stig

Hi, I just had enough of this bike, it is not charging properly and is giving me problems, so I was about going to get rid of it and buy an another 300cc Xciting in a lot better shape, agreed with the seller to have a look at it and would have sold this scoot at a loss with some known problems. But yesterday my car suddenly stopped and it turned out to be a broken cam chain, which is a massive headache and a huge cost so I will hold on to this bike for a while now... Anyway, today I managed to source an M41 wrench, a strap wrench and will dig in the clutch first thing tomorrow morning. Will see, what I'll find, I watched those youtube videos so I guess loosening the nut will not be an issue. How I will torque it down properly afterwards? Well, that's a good question but I will try the two feet method, you mentioned.