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Post by phatboy on May 3, 2016 4:15:50 GMT -5
I need to go to stock variator for a while (a new china variator I bought fried itself after just 50 miles). The old variator worked fine, but the problem with it (and the reason I tried to replace it) is that no matter what I did I could not get the belt to ride all the way up on it. Could never get that last 8 mm of unused travel on the edge of the variator.
I was thinking, what if I try a belt that is just a little longer, say 10-15mm longer, with same width and angle. Assuming the belt is not so much longer that it would rub, could the extra length make the belt ride up the variator higher? Or would it make things worse, like, ride the same on the variator but ride up the clutch more instead?
I don't see much talk about longer belts, has anyone tried it and how did it work? Or is this really just a bad idea? Or is the answer a shorter belt instead?
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Post by gy6er on May 3, 2016 7:58:15 GMT -5
My 170cc tunes pretty mean w/ the 842,but 150cc bike somehow loves the 835mm one though. The 170cc has gear to the cealing. Maby that's why. Battle cat ( 170cc) will downshift a whole lot better also with 10 gram dr puelly round roller weights.
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Post by phatboy on May 7, 2016 22:17:16 GMT -5
I got a belt 12mm longer than stock and saw absolutely no difference in top end. I marked the variator with ink, and measured. its 5mm actually (8mm was a guess.) Heavier rollers don't make a difference in how much ink is left. With this setup the scooter is topping about 40-42, too slow.
I think the answer is a wider belt, not longer, to make it ride higher on the variator. I found a belt 1.7mm wider than stock and about the same length. I've ordered it and will report results.
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Longer belt?
by: JerryScript - May 7, 2016 22:38:07 GMT -5
via mobile
Post by JerryScript on May 7, 2016 22:38:07 GMT -5
I have seen posts about changing belt size improving performance, not sure about top speed. I believe most were used scooters that may have had the wrong size installed when sold.
Top speed can only be significantly increased by changing the final drive gears, and that usually requires a BBK to push.
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Post by gy6er on May 8, 2016 7:37:56 GMT -5
No no no....I know that sound, not on the big boys...ease w/ that huge 115mm variator. Mutch mores ease. Cuts the rpm,'s a whole lot.
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Post by rockynv on May 9, 2016 4:22:47 GMT -5
If the drive faces are worn on the variator it won't close enough to ride the belt out however if the sheeves on the clutch are not opening all the way that will also prevent the belt from riding all the way out on the variator and a wider belt will only make this worse. You really need to verify that both the clutch and variators drive faces are not overly worn out and that the clutch is not sticking so that it won't open all the way up preventing the variator from closing.
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Post by phatboy on May 9, 2016 15:21:20 GMT -5
The china variator that broke on me was oversized, and comparing with stock it also had a flatter ramp angle, so belt must have been higher up. I got about 5 mph more out of it. I am starting to wonder if this is the right approach though. With this setup the china belt shreded after 50 miles, maybe it was riding too high on the variator and rubbing on the inside of the case. The wider belt I got on order is a Bando, if that shreds I will look into regearing. Also been running with the CVT cover off while tuning, is that a bad idea? JerryScript I checked the gear ratio by spinning the clutch 100 times and got about 7.5 revolutions of the rear wheel, so final drive ratio is about 13.3:1. Based on a thread I found, other 49cc scoots seem to have a final drive about 11:1, so my bike does seem to have pretty deep gears on it, probably would benefit from taller gears. When I get a chance I will open it up and look at what it really has. rockynv the clutch does not seem to be sticky, however I am not sure of the variator face, I do see a definite darker area where the belt runs 5mm from the top of the variator, not sure if that means wear or not, or if the face should be cleaned (or it can be) I will post a pic when I get a chance. |
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Longer belt?
by: millsc - May 9, 2016 22:41:14 GMT -5
via mobile
Post by millsc on May 9, 2016 22:41:14 GMT -5
I run the 842 belt instead of the 835 its longer didnt really notice any improvement but it could help so i use it lol
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Post by rockynv on May 10, 2016 0:02:36 GMT -5
You can clean the drive face with a fine nylon scouring pad with a very little bit of brake clean on it. Once clean you can put a metal machinists ruler across the drive face from the center to the outer edge and if you can slip a 0.3 mm feeler gauge between the metal rule and any spot on the drive face then most would consider past end of life.
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Post by phatboy on May 11, 2016 19:00:40 GMT -5
OK, got the wider belt today. It was good for about 3 mph on the top end and no loss of power on the bottom end.
The weird thing is that the ink on the variator has barely moved. It is 4mm still, so the belt is only riding 1mm higher on the top end than a stock width belt. It is surprising that 1mm can make that much of a difference. I am at a loss to explain it.
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Longer belt?
by: JerryScript - May 13, 2016 18:10:41 GMT -5
via mobile
Post by JerryScript on May 13, 2016 18:10:41 GMT -5
Wider or longer belt?
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Post by rockynv on May 13, 2016 22:05:40 GMT -5
OK, got the wider belt today. It was good for about 3 mph on the top end and no loss of power on the bottom end. The weird thing is that the ink on the variator has barely moved. It is 4mm still, so the belt is only riding 1mm higher on the top end than a stock width belt. It is surprising that 1mm can make that much of a difference. I am at a loss to explain it. For every action on the varitor there is the opposite reaction on the clutch sheave. 1 mm higher near the outer edge of the variator can pull the belt several mm deeper down between the clutch sheeves. |
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