Ive heard that not all belt drives are the same. For instance, in the AC and Yami, the belt is always spinning when the motor is, even at idle. The polaris, and im not sure which others, the belt does not spin, unless the revs come up beyond idle speed.
That must mean there is some kind of clutch, inside the cases, on a Yami to disconnect the belt drive, from the wheels, while idleing in high/low/reverse.
Any good reasons why the polaris is the way it is? why the Yami is the way it is?Advantages/ disadvantages?
Id like to be better informed, when it comes time to buy.

 

The belt may spin a little on the Polaris machines at idle, but it shouldnt really that much.. What happens is when you bring up the RPM's there are weights in the primary clutch (attached to crankshaft) that force the clutch to get smaller. It brings the clutch sheaths closer together which forces the belt to go up and ride higher on the clutch sheaths. You can adjust the "engagement" of the clutch with different weights and spring. You can have it engage sooner or later, depending on how your riding style and engine performance is. When the belt starts to ride higher up on the primary clutch, it pulls the belt further down in the secondary clutch (attached to trans). There are "buttons" and a helix in the secondary clutch. I am not too sure how that works, but the secondary clutch is what give you more speed. I hope I have shedded some light on this for you

 

Thanks guys,
still wondering why the yami is always engaged...is it for engine breaking, even if the motor dies?Is there another clutch involved on a yami, internal or external?Which system is easier on belt life?

 

What is meant by "always engaged".....is that the belt is actually tight to the sheaves and the clutch and belt are NOT spinning at IDLE....Polaris is like a snowmobile clutch....the clutch is spinning at Idle....but the belt is not.

When I first got my AC, I thought that engaged meant spinning also....but I took it apart and found otherwise...the belt is tight and only spins with throttle.

 

my brother has a ac 375, and i thought the belt was always spinning.
Maybe the yami has a centrifical clutch before the driving clutch, i thought it would be after the driven clutch.
I know the polaris works like a snowmobile, where the sheaves on the driver side open up at idle, the the belt goes slack.
Do you know of any diagrams, or articles on the clutching of yamis?

 

This is a topic I'm very interested in as I'm looking for a second machine. Yam has the Ultramatic tranny which is rated to be the best, it hardly every burns belts, you'll never see one with a blown belt, very rare and I've seen them driven really hard, where as the Polaris uses the Sled type clutch that blows a consider amount of belts, why wouldn't Polaris change and go with the best clutch, called the Ultramatic, which Suzuki and Arctic Cat have also or very similar as they dont' have belt problems either. Yes the AC650 seems to be having problems but that is because they are having to use the Kawi system which is also not that good.
What is it that makes the Yam VBelt Ultramatic Clutch so strong. I had a 600 grizz and abused it in high and low and never once had a belt blow where friends of mine had SP 500's and drove them like me and had blew belts or had to change them frequently. I even got water in mine 3 times, and when I got the clutch checked everything was fine. No wonder they are rated #1 in magazines, if Polaris would just look into a better system they would have more people buying them like me. I love the look of the SP's and am still considering buying one as I want to stick with the 500 series and yam only has the 660.
And people please don't argue that you don't have belt problems, if you don't its because A you don't drive it hard in high gear or second you use LOW gear where you should. But if you pound it in high say bye bye to your belt.

 

OK, first off, you should not be "blowing" a belt. If a belt "blows" then it is a defect in the belt, not the machines fault. Second, these machines have a low gear for a reason. If you are determined to not use the machine in the way that it was designed to run, then dont expect the belt to last very long. As long as your clutch compartment is sealed properly and everything is adjusted accordingly and in alignment, then you should not have any belt problems as long as you use the machine in low when you are suppose to and dont exceed the limits of the machine. You said it yourself, if you dont have problems then you are using low gear when you SHOULD!! I have only had 1 belt problem. It was the original bely on the machine that started to shred. That was due to a defective belt, not my machine. But I have never smoked a belt or had one "blow". I have had it slip once, and that was due to my own stupidity. And trust me, nobody beats a machine harder in the woods than I do. I dont ***** foot around

 

I'm sure I've heard it said before, that Polaris needs to be in low,unless youre really going fast. But yami says to leave it in high, and just go to low when more power is wanted at low speed(towing, mudding).Is it because the polaris clutch suddenly closes, on a slack belt, and that causes hot spots?(from idle ,in high range, nailing it)
Someone in another forum said the yami has a centrifical clutch on the driver side of belt arraignment, and the belt is always tight on the sheaves. When a certain rpm is reached, the centrifical clutch, spins the driver side, so there isnt the sudden squeeze on the belt(and slippage) that polaris has,( going from slack belt, to moving.) this could account for the reason the belts on yamis last longer.
still undecided on which is the machine i want to buy. the more i find out ...the more i realize i dont know enough.

 

HondaBuster,

You sound like you know about it, all I know is they are always engaged and seem to be a better belt, like alot of people I know, it is crappy to always have to be thinking about if you should be in LOW gear, and that said, the YAM clutch has been rated the best belt tranny as it is the next best thing to the Honda's tranny's. So why don't other company's like Polaris, Kawi, and even Bombardier realize this. They seem to use SKidoo based clutches that work on sleds but not well on ATV's, they should go to the Ultramatic VBelt clutch that is more durable and doesn't have belt problems.
Sure if you drive a Polaris right it won't have problems but I don't like thinking if I'm climbing a steep hill or not going fast enough that maybe I should be in LOW gear as I'm going to burn a belt. Then only good thing is the Polaris belts are cheap to buy, but I'd rather only have to buy one after 10.000 Km's then at every 2000 km's right. The same with the Kawi, I have read where people said they have great mileage on there belts, ask what it is and its 2000 km's, well that is nothing for mileage, when you get up near 10000 then your getting up there.
Hopefully the company's mentioned start to realize this, AC 650, well they are already talking about shieve pins and crap to help the belt out, Yam have never had any problems at all, someone got it right the first time hopefully everyone else see it and starts copying it. Polaris was the first, Yam was the second and they got it right, right!

 

Anyone know whether the a/c and suzuki use the same belt drive? Like on the eiger, is it the same as the 400 cat? I havent heard too many complaints about the suzuki, belt drive.
Its one of those things, my interest in the different belt drives, that drives me to ask these questions. Ive made some purchases in the past, and thought i knew enough, to make a good decision. Then,I go out ridin with group and find, that there are issues i never thought of. Its much cheaper and easier to ask the questions and get the answers, before writing a check. Also i do all of my own repairs and maint. so i want to know what im in for, ive never owned and automatic.
Still waiting on hearing from the polaris crowd, on the good and or bad points of the pvt system,as opposed to the yami system.