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Post by 2strokd on Jun 17, 2010 8:07:36 GMT -5
:stumped: Well im glad to here the trusty ole Bando came through again! Hope this one lasts! For the heat?  I know ya got good gear oil...No head temps to report? But im sure you would know if the engine is getting hot...I dont know buddy! I will think. Maybe its time for the BIG CVT cooling mod with a PC fan or two(pusher and puller) and a R/C car battery? ;D Same clutches and bells you have used before? |
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Post by 90GTVert on Jun 17, 2010 8:25:34 GMT -5
Stock clutch and bell that came with this scoot. I did lighten the clutch, but it doesn't slip (when it shouldn't) that I can tell.
I think before I put fans on there I'd probably just cut half the cover away. I've been very tempted to cut the center of the cover out like I saw in one of the racing vids I posted here.
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Post by 2strokd on Jun 17, 2010 8:30:09 GMT -5
Do it!!!! It would look cool and hopefully work that way!
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Post by 90GTVert on Jun 17, 2010 13:42:17 GMT -5
I've got the back about done. The front is just rough cut. A bandsaw and straight cuts would be so much easier, but I kinda like the covers having some character. Apparently character requires lots of hacksawing and filing.    If this won't keep ti cool... |
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Post by andsetinn on Jun 17, 2010 14:46:25 GMT -5
Wow, 6 belts in one month.
Well, heat means friction and friction means heat :doh: .
This mostly happens at wide open throttle. The scooters have been tuned for maximum power. There are signs of the belts touching the outside of the cvt cover which might give indication of the belts becoming slack (not enough tension or you're using too long belts?) High speeds of course mean high load on the CVT, belt and clutch. I don't know how much you weigh, it could be a factor.
The belts are chewed on one side, maybe the variator faces are too coarse or fine, the chewing could also be caused by the belts overheating and melting. Also check the wheelaxle (rear pulley) and its bearings, it could become misaligned under highspeed load. The belt could be going "too high" on the variator causing it to just grap the bottom edge of the belt.
If the scoot doesn't want to downshift, the contraspring might have overheated and permanently lost tension sometimes earlier. You could try replacing the contraspring.
Are you using Kevlar belts?
Have you cleaned all traces of oil or gunk from the sides of the variator faces?
Have you checked the clutch and contraspring for signs of overheating.
The guides for the backplates disappear, probably the results of over reeving when the belts snap, but it might mean that the backplate moves too much because you've removed too much material from the variator.
I'd say that either the clutch or the belts are slipping causing the belts to overheat and snap. I'd try new variator, new clutch and contraspring with new Kevlar belt and see if that works. Also check if the belts, or rather the variator and rear pulley, are in alignement.
Of course you might just be extremely unlucky when buying belts.
The weird thing is that this happens to both scoots. It probably mean that the failures are the results of something you've done to both scooters.
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Post by duosport on Jun 17, 2010 15:57:57 GMT -5
... The belts are chewed on one side, maybe the variator faces are too coarse or fine,... The weird thing is that this happens to both scoots. It probably mean that the failures are the results of something you've done to both scooters. Ah hello! I say put in a stock variator that is un-ground and see what happens. |
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Post by 90GTVert on Jun 17, 2010 18:52:06 GMT -5
Welcome to the site andsetinn. Thanks for all the ideas. I have stopped seeing any signs of wear on the belt of the Venus. Not messing with the other till I get one straight. I know the belt is slack at idle. I posted a video that shows that. As soon as I give it gas, it tightens up. I do think that the cheap belts were at least part of the problem, but not the whole problem. I found the poor performance issue tonight. When I pulled the variator off tonight, I found that the slides were broken. That makes it really hard to move the back plate. You can see that the guides are worn. I was hoping to salvage the vari for a bit, but I think there's just too much movement there.   I stuck a barely used variator (just like what came off of it) on with the same sliders. Same rear pulley/clutch setup. It acts completely different now. It bogs on the initial takeoff because the variator is not modded at all and even with 3 spacers the belt kinda grabs too early. Once it picks up after just a second it takes off hard and pulls the wheel up a bit sometimes. Now it revs too high at cruise. I got as high as 50MPH, but the belt isn't getting full travel now. I'd say nothing has been permanently damaged by heat, becase that contra feels mighty stiff now. At 30MPH in town I just felt like a jerk with a loud pipe and revving just to cruise. lol I definitely need to straighten some stuff out there, but it's looking like the worn vari may have been causing at least part of my troubles. With the open CVT cover, the belt and trans parts are definitely staying cooler. Before I could hardly stand to touch the belt it got so hot. Now I can easily grab the belt after a ride. It's not cool in there, but it's fairly cool for a CVT and way better than before.  |
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Post by Fox on Jun 17, 2010 19:20:42 GMT -5
That's great work Brent! It looks cool (no pun intended)  |
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Post by duosport on Jun 17, 2010 19:55:00 GMT -5
The surfaces of the Sheaves are polished. They come that way. Is it not part of the function of these parts to allow the belt to slip? If there was something good in having a textured surface, then maybe the whole surface of the sheave would benefit from such a texture.
You are very knowledgable about scooters. I have really appreciated your patients and advice here on the forum, but the grinded sheave is part of an experiment, right? FRom what I see on the thread about that mod that you did, only one side was grinded down right? Does that side correspond with where the extra wear was occuring on the belts?
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Post by 90GTVert on Jun 17, 2010 23:47:47 GMT -5
I ground both sides. It is still an experiment, but filing the center and adding spacers definitely works. 2strokd and I, and I'm sure many others, have seen the effects first hand. I think what I need to be careful of is just how far I go with it that might allow the vari to open too far like andsettin suggested. You don't want to leave burrs or really rough surfaces, but anything I've put on has not been all that rough. I think it looks worse than it is. I generally go over them with sandpaper before installing. I don't just leave the filed surface that could have burrs or something.
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Post by redorchestra on Jun 18, 2010 0:42:41 GMT -5
One more possibility and this ties into a video I saw posted (here I think but here anyway www.youtube.com/watch?v=y7h4OtFDnYEIf ) about how a train uses slightly conical wheels to stay on the tracks. the belt is not perfectly centered on the variator faces it is going to be riding on one face more than the other at a slightly fatter diameter. If it does that the other face will want to speed slow down because the belt hits it at a skinnier diameter. Since the ramp plate is attached directly to the drive shaft, and the stationary plate is connected directly to the drive shaft, the only free plate is the one that moves. and from the way the plate sliders are worn you can see that it is torquing itself. I think the face is trying to slow down to compensate. My recomenda-guesstimate is to shim behind the movable face half of the amount that you have moved the stationary face inward. |
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Post by 190mech on Jun 18, 2010 4:46:16 GMT -5
Just read the updates,INTERESTING!My concern is that the cover assy is a structural member that ties the whole mess together acting as a big tube swingarm,with a major portion missing some flex will surely happen,possibly failure with time.Always thought that the dowel pins positively located the cover with the many attach bolts to create stiffness..Just a thought...
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Post by 90GTVert on Jun 18, 2010 6:49:52 GMT -5
Oh boy. So my next post will probably be pics of an engine split in half.
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Post by Fox on Jun 18, 2010 8:24:45 GMT -5
Oh boy. So my next post will probably be pics of an engine split in half. I've seen other posts over the years about how the cover is a structural member but I don't buy it. Those little 8mm bolts are sloppy in the pass-thru holes in the cover so if the case want's to crack it will regardless if the cover is on there or not in my opinion. The engine case has the criss-cross material cast into it to provide the strength. The only reason is should break is if you overload it, jump it, or hit a pothole or a speed bump too fast. |
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Post by 2strokd on Jun 18, 2010 8:52:52 GMT -5
I gotta agree with John here...Glad its staying cool now, but he does have a good point!
Remember that you-tube vid were the dudes case breaks after a stoppie?
I know he was riding double and doing a stoppie but?!!!
I(we) push our scoots hard sometimes!
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I know ya got good gear oil...No head temps to report? But im sure you would know if the engine is getting hot...I dont know buddy! I will think. 
