Variator Tuning and riding conditions

[ZoomZoom]

I remember reading somewhere, someone toasted their belt riding around on bush roads. I think that would happen because of low rpm's for a longer than normal times. My question then is: When riding off road, would it be better to run with lighter rollers to keep the variator rpm higher since you never cruise at high speeds most of the time? Does this make sense?

[Dandy Dan]

I think I recall what you are talking about. I believe this guys failure wasn't caused by the belt though but rather by the rear clutch. See our rear clutch has two shoes like a drum brake and they are held tightly in when you are stopped by 1 spring each. When you twist the throttle the shaft they are on starts to spin and the centripetal forces starts to counter the inward pull of the spring and thus when it spins fast enough the shoes fly out and grap the outer clutch walls which completes the linkage and thus your rear wheel is engaged. However, if you have a lot of power you can 'slip' the clutch which just means that the shoes don't instantly grab the wall but rather they slide a bit before they can grab the wall cuz the wall is spinning so fast. I think what happened in this guys case is that he was driving at just the speed when the clutch shoes are starting to fly out and grab the wall but weren't able to fully engage. They were just brushing against the wall. This is bad because the shoes really start to heat up when this happens and they wear. So yeah I think what happened is that his clutch wasn't fully engaged so the clutch was slipping thus heating up and then it eventually overheated and seized. It could be possible that his drive belt melted when this happened but it wasn't the cause of the problem.

His problem would be the same thing you'd get if you drove around for a long time in a car with a manual tranny and you had the clutch pedal 1/2 way down.

Changing your roller weights won't do much to solve this because off the line the rollers, regardless of their weight, haven't really done anything yet. It's not until you're up to 5 mph or so that they start to open the variator and by this point the clutch is already engaged. This clutch issue only arises if you cruise around for a long time at a very low speed. Even city riding is way above this so I wouldn't worry about it.

There are a couple ways you could alter the situation though. Do you know the outer piece of the rear clutch? It's basically all you see when you take the drive cover off and look at the clutch. It's the dome shaped piece that might be slighly rusty or if not then grey. The clutch shoes are inside this and they fly out and grap onto the inner walls of this dome. Anyways, I've seen aftermarket ones of these on ebay that have bigger cutouts so the heat disappates quicker. You likely will never need this but if you were racing bikes say and slipping the clutch a lot then it might be good to have. It might have saved this guy for another 5 min. A 2nd solution would be to try some aftermarket clutch shoes (I believe Jiang Wayne sells some for the Ruckus). I don't know if these would do anything or not but they might slip/operate at cooler temperatures or they might grab better so it'd be harder to slip the clutch. Lastly, you could play with the stiffness of the springs in the clutch (not the big compression spring but the smaller clutch shoe springs). These springs hold the shoes in so obviously stiffer ones will make your clutch engage at higher RPMs and vice versa. If you went with stiffer springs you'd get harder/faster launches because you bike would rev up and then grab (like revving a car up and then dropping the clutch.) but they would also raise that dangerous speed at which the clutch is partially engaged so that it is at a speed you might actually use if you were say, in gridlock traffic for hours or slowly off-roading. The opposite swap (lighter springs) would give you a softer launch since they'd engage a low RPM (our engine just revs higher and higher until it engages so the sooner you engage the softer it'll be). This would lower that dangerous speed to like 2 mph I'd guess....even if you did cruise at this speed it wouldn't be quite as dangerous because you would be moving slower so your clutch would be doing less slipping as everything would just be moving slower.

In summary, just don't cruise for long periods at very slow speeds. Anything above 10mph is for sure safe and likely above 5mph should be cool too. Failure only happens though if you wear out your pads which takes a very long time (20,000+ miles) or you overheat the clutch (I'd guess 5 min minimum but more likely 15-30min.)

[ZoomZoom]

WOW Dan! Thanks for the excellent explanation. I understand what you are saying and it makes more sense then playing with the rollers.

One thing I noticed on the ruck was there doesn't seem to be an inlet duct, that's what it is called on my Polaris atv, on the tranny case cover. I wonder why?

[Dandy Dan]

No problem. One other thing I should add is that the most likely way for you to overheat the clutch is if you have your idle set too high. If it's high enough that your wheel spins on the center stand then your clutch is atleast partially engaging. Even if you set it high enough that it fully engages on the center stand it's gonna be slipping if your stopped at a redlight cuz it's the first thing to give. When you set your idle go for a nice 10 min ride to let the engine heat up because that really changes the idle and because when you first fire up your engine the cold enrichment valve in the carb is open which dumps more gas in so your idle might be high for the first miniute and then settle. Ideally, set it so that your wheel doesn't turn at all when it's on the center stand but still high enough that it doesn't take 2-3 seconds to rev up and engage.

About the inlet duct...I'm not familar with these cuz the only vehicle I really know is the Ruckus. I'm assuming you mean this hole ventilates the drive unit right? I'd guess that we don't have one either because Honda wanted to make sure the rain/crap stays out or because they figure that our clutch is small enough that it should be fine without one. The later guess seems more likely but it's still just that, a guess.

I wouldn't worry to much about this problem as it would only occur under abnormal circumstances unless you're idle is really high.