I posted this in another thread:

I thought all belts had Kevlar in them - the aftermarket ones are advertised as 'Kevlar belts' in order to sell them.
From experience - the Piaggio belts last much longer than the am ones (as do the Honda ones in the X9250sl maxis) and show signs of wear, unlike the am ones which usually fail with little or no warning.

I would imagine so, but you want to be careful getting them too far away from the stock settings.

I've never thought of that before. All the belt-slap discussion centers around which belt to use, but changing the tension isn't discussed in that context. More tension would raise the frequency of the oscillation, like tightening a guitar string. The amplitude should decrease, though, so the belt will be less apt to strike the plastic cover. That's my guess, anyway.

OK.....

Stronger "big spring" wants to keep the driven pulley squeezed together, and resists changing to higher gear. It counteracts the effects of heavier rollers. The stock rollers are already as heavy as you'll find. So you'll have a slower runup through the "gears." Kind of like having lighter rollers. As you decelerate the driven pulley will tend to go back into "low gear" more quickly.....

Oh, hell. I give up. Try it and let us know.

I think it would act the same as putting lighter rollers in the variator.

It seems that the belt is always under tension from the variable centrifugal force from the rollers in the variator (trying to press the variator together) being resisted by a static pressure from the contra spring in the clutch. By putting lighter rollers in, the contra spring in the rear becomes comparatively stronger, keeping the driven pulley pressed together, giving it a lower gear ratio. Usually, we put in lighter variator weights to allow the contra spring (I think that is what the big spring in the clutch is called) to keep the driven pulley pressed together - its just a lot easier to change variator weights than a clutch spring.

I would guess that, if you put a softer contra spring in the rear and lighter variator weights in the front, the machine would act the same as a stock machine, with the exception of a lot of slop in the belt. That is why I think that heavier weights and contra spring might get rid of belt slap. When I rode a mountain bike and we would get chain slap, we just took out a couple of links. A shorter chain was under more tension and didn't slap.

I don't really know! I'm just a theoretical guy. Besides, I already put in a J Costa and it got rid of most of the slap.

Philip

Belt Slap?? What is that?? (grinning) I don't have any since I installed the J Costa...