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Post by atma on Jun 6, 2015 20:40:02 GMT -5
Hey guys. So, here's the thing. I put new guides on my variator about a week ago - Dr. Pulley. I imagined they would last forever, right? To my surprise, they have vanished. Obliterated completely, only to leave bruised metal in it's wake. The stock ones I had on there were coming apart at the seems, literally, though they ended up lasting 3k km. I would imagine that the new, beautiful Dr. Pulley ones would at least double that mileage, but not at all. There must be something wrong somewhere in the CVT, yes? Also, on the belt, (which this is the third one...first two cheap chinese, this one's kevlar) there happens to be this line of wear that appears. I figured it was because of the horrible guides i had previously, letting everything knock around too much, so I flipped the belt after the guide change to see if the line would still appear. It has. Since the new guides have gone MIA, the belt wear could still be caused by the moving and shaking of the guideless variator, yes? I did, however, find one tiny remainder of one of the guides, in the bottom of the CVT cover. Anyone know what could be going on? I'm ordering a new variator tonight, definitely- but could it be clutch related? The spring seems fine, the clutch shoes are decent, no misshape on the clutch bell, etc. Something i'm missing? I'll attach some photos. Image of the wear  Damage near the weights  Hope everyone is having a nice day so far, by the way. |
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Post by tvnacman on Jun 6, 2015 21:12:06 GMT -5
that variator look pretty bad, this is a good replacement. I would get a belt too. John |
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Post by nulldevice on Jun 6, 2015 22:04:11 GMT -5
The back of the belt is hitting something within the belt housing. Are you sure you are using the right size belt? Too long a belt will let it flap around and strike something. Also, check the operation of the driven pulley. That belt isn't pulled down all the way into the center of the variator pulley like is should be.
The destruction of the U shaped variator guides leaves me puzzled.
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Post by JerryScript on Jun 6, 2015 22:08:17 GMT -5
With a too large belt, it is possible the variator is open without the weights pushing it. Without tension, the ramp plate can have enough room to wiggle, which would destroy the guides.
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Post by atma on Jun 6, 2015 23:39:50 GMT -5
The back of the belt is hitting something within the belt housing. Are you sure you are using the right size belt? Too long a belt will let it flap around and strike something. Also, check the operation of the driven pulley. That belt isn't pulled down all the way into the center of the variator pulley like is should be. With a too large belt, it is possible the variator is open without the weights pushing it. Without tension, the ramp plate can have enough room to wiggle, which would destroy the guides. Funny you mention the belt being too long, that didn't really occur to me. Its a 1p39qmb, would that change the belt size at all, even by .1 somewhere? I've heard of 669-18.1-30, and so on. Also, would the system not adjust the belt into the correct position whilst moving? Or is that done manually, and i've been putting the belts on incorrectly all the while? That would makes sense, most likely elongating the belt, causing all the problems.. I'm purchasing a new variator and clutch pulley assemblies in the morning, i'm hoping this will fix any problems. The only things that aren't stock on this scoot are the carb, the CDI, and the belt. what better time to change that, eh? |
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Post by JerryScript on Jun 7, 2015 0:52:28 GMT -5
There are several belt sizes, and you can often tell which you have by your wheel size.
For 50cc with 10" it's usually short case with a 669, 12-14" is usually long case with a 729, the QJ variant with either 836 or 891.
For 150cc with 10" it's usually short case 743, for some it's 835, and the weird 815 wide belt, 12-14" it's usually 842, and 16" wheels use a 906. There are many others, and a multitude of widths and thicknesses.
On my 50cc with 10" wheels, the belt has to be almost all the way down in the clutch just to get it over the crankshaft. On my 150cc with 16" wheels, I barely have to compress the clutch and I can slip the belt over the crankshaft easily.
In that picture, it appears you have way too much slack in your belt, but it's hard to tell. A video of it running would help.
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Post by onewheeldrive on Jun 7, 2015 5:12:36 GMT -5
If you have a 669 belt then your belt size is fine, unless the numbers are lying or the belt is defected, because 669 is the shortest belt I know of for 139qmb. The pic showing your belt looks like the belt was just put on, after tightening the variator/clutch nuts and just before starting the scoot for the first time --- it always has slack at that moment on the variator side.
The slack is a good thing because you don't want to tighten the variator drive face down onto the belt. You want the belt to be able to move freely on that side but only for tightening purposes. That way, when you put the drive face on, the belt doesn't interfere with proper positioning so everything fits like it's supposed to. With no slack the belt gets in the way.
After putting a belt on, tightening the pulley nuts, and before starting the scoot, I rotate the belt by hand counter-clockwise until there is no slack left and the variator turns. By the time I'm done rotating the belt by hand, the belt will no longer be down in the clutch and will be down in the variator-- as if the belt change never happened. I like to "prime the belt" before starting.
The wear mark(s) on top of your belt could be from rubbing against the starter bendix. I have those marks on probably 5 belts in my garage. It's basically one continuous line all the way around the belts. As long as the bushing(s?) the bendix sits into are ok, then I think it's just the way some of these engines are designed. Chinese scoots aren't perfect. See if the closest part of the bendix (to the belt) is directly above the line on the belt.
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Post by tvnacman on Jun 7, 2015 6:47:22 GMT -5
I would like to see the boss the variator rides and slides on too.
John
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Post by nulldevice on Jun 7, 2015 8:41:15 GMT -5
Atma, is the photo of the belt during installation or after you have run the scooter?
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Post by cyborg on Jun 7, 2015 8:59:32 GMT -5
Third party observation what's with the galling on the bore of the variator,,,, that doesn't look good,,, is the shaft it sits on ok?
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Post by tvnacman on Jun 7, 2015 9:14:00 GMT -5
ok twice you have been asked about #6 we can see in your pictures that #7 is damaged.  John |
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Post by cyborg on Jun 7, 2015 9:46:20 GMT -5
How many miles on this bike? the variator looks worked to me,,,needless to say i would give the crank shaft a serious look all the way around and i also would check for runout with the shaft as well
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Post by onewheeldrive on Jun 7, 2015 12:36:23 GMT -5
I would like to see the boss the variator rides and slides on too. John Yeah that inner bushing of the variator looks toasted. I would guess there is a bit too much play between the variator and the boss, because of the worn bushing. Maybe even take a pic of the boss inside the variator. |
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Post by atma on Jun 7, 2015 16:46:05 GMT -5
Atma, is the photo of the belt during installation or after you have run the scooter? This was as soon as I opened the case yesterday to document the belt wear. |
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Post by atma on Jun 7, 2015 16:49:48 GMT -5
The wear mark(s) on top of your belt could be from rubbing against the starter bendix. I have those marks on probably 5 belts in my garage. It's basically one continuous line all the way around the belts. As long as the bushing(s?) the bendix sits into are ok, then I think it's just the way some of these engines are designed. Chinese scoots aren't perfect. See if the closest part of the bendix (to the belt) is directly above the line on the belt. Exactly. It is one continuous line all the way around. And yep, it sits right above where the line is. I was wondering if there was something i could do to fix this? Would this cause major belt damage over time - or just cause the minor line to a certain extent and doesn't get much worse from there? |
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