Clutch info for cvt needed

[Nocomment]

Guys can anyone tell me for a 90cc cvt with engine work, what is a good setup for clutch componets? I spoke to hetricks and they have OEM front variator and rear clutch with a national mod done to them that sounded interesting. But I'm not sure what a National Mod is. I am also looking at the Malossi setup too. any Ideas.

thank you

[chickenman26]

call billy at wrh racing he will hook you up!!!!!

[Livin4Real]

there's endless possibilities with clutches and you can also hose one up pretty good if you don't know what your doing. Hetrick along with others machine new ramp angles on the variator, along with lightening the shoes, trying different torque and clutch springs, belts, bells, rollers etc. You can see how it can go bad really quick. If you can find someone nearby that does engine work and have them sit down and do some OJT would help a lot. It would help alot to know exactly what has been done to your engine to find a starting point on the clutching.

[jetski_dawg]

depends alot on the type of track you run also

[Nocomment]

Originally posted by Livin4Real
It would help alot to know exactly what has been done to your engine to find a starting point on the clutching.

ts's a 90cc with a 52mm airsal cylinder, pvl ignition, 28mm carb. hetricks exhaust, the clutches have been lightned and red springs all around, 5gr rollers.

I have been playing with springs and rollers, changed to a malossi belt, and the guy who did my motor work set up the clutch pretty good, but Its all stock componets and were looking for more launch out of the corners and a steader top end.

[ecmini1]

By the sounds of your set up it sounds good , There are a lot of little factors rider weight, carb jetting etc. that can make a little more of a diffrence. If those clutchs parts have been install for a while it just might be time to go in an freshen them up. Heat and wear will change your set up after a while. Try a diffrent ramp variator koso makes one with a great ramp to it.

[etondaddy]

Originally posted by Nocomment
Guys can anyone tell me for a 90cc cvt with engine work, what is a good setup for clutch componets? I spoke to hetricks and they have OEM front variator and rear clutch with a national mod done to them that sounded interesting. But I'm not sure what a National Mod is. I am also looking at the Malossi setup too. any Ideas.

thank you
I sent you a PM

[i-zapp]

can you spell R&D? even with the best info, ultimately you will need to dial it in yourself, and that will require some trial and error. and btw, the correct clutch setup has little if anything to do with rider weight or specific track. it's either right, or wrong. i'll argue that till i'm blue in the face...

[miniquad]

So the clutch set up for a 125 pound kid is the same as a 50 pound kid. If that is the case then there should only be one clutch set up that works for everyone that would be really simple. Does anyone carry this one particular clutch setup if so im interested.

[ww228king]

same here!

[i-zapp]

Originally posted by miniquad
So the clutch set up for a 125 pound kid is the same as a 50 pound kid. If that is the case then there should only be one clutch set up that works for everyone that would be really simple. Does anyone carry this one particular clutch setup if so im interested.

if it's dialed in correctly on the dyno, then it'll work on the track regardless of whether it's my own 165lb riding it, or my 65 lb rider. and i did not say there's one "works for everyone" setup. i meant that each setup needs adjustment and tuning to get it right. once right, there's no further need to adjust based on rider or track.

[wvspeedfreak]

I agree with you too an extent but I do know that rider weight affects which rollers work best all else being equal.I built my sons Kasea 90 and with light rollers in it the thing would just light the tires up off the line.I changed the roller weight to 1.5 gram heavier rollers and it allowed the quad to come off the line with less tire spin and get moving a little before it really turned on.He weighs 68 pounds completely decked out in his gear.
Now with a heavier rider on this same set up it will seem a little sluggish out of the hole and lighter rollers would be a better set up because he would have enough weight to keep the tire spin reduced with the engine coming on quicker.
I am just stating what my experience has been.

[jetski_dawg]

Originally posted by Nocomment
ts's a 90cc with a 52mm airsal cylinder, pvl ignition, 28mm carb. hetricks exhaust, the clutches have been lightned and red springs all around, 5gr rollers.

I have been playing with springs and rollers, changed to a malossi belt, and the guy who did my motor work set up the clutch pretty good, but Its all stock componets and were looking for more launch out of the corners and a steader top end.
id try dropping it down to 4gr with a 52 top end..keep the 5 if you decide to go to a 54mm cylinder.. also change the little springs to the blue or stock......just my .02

[bstuart]

The weight of the rider is one of the MOST important aspects of the setup. If you change the overall weight of the quad/rider you are losing performance if you don't adjust the clutch to match. Think about it, more quad weight = higher rolling resistence from a stop, which means you would have to adjust the clutches to compensate. Maybe not for just 5 or 10 pounds but certainly from 65lbs to 165lbs!!!!!!!

Believe me, I have a 115lb 11 year old on a 90cc and its a vastly different set up than my 51lb 9 year old on her 90cc.

[i-zapp]

okeeedokeee, then. see you at the track.
:eek2:

[mmullins14]

I agree with I-Zapp. If the clutch is setup right, the weight of the rider shouldn't matter much. But I am curious as to what you would adjust on the clutch to accomodate a heavier rider. You said the setup was different between your 115 pound rider and 51 pound rider. What changes did you have to make?

[drr5]

my feeling is if you have a hevier rider the torque spring would play a major role . more weight more spring.

[Livin4Real]

Don't let I-Zapp's low post count fool you. He's been around for a long time on other forums and knows his stuff. Once your clutch is setup correctly your good, if you start trying to compensate bottom for a heavier rider you will lose in other areas. Obviously a heavier rider is going to have a slower holeshot over a lighter rider but you have to look at the overall performance of the clutch setup not just one area.

[bstuart]

The objective is to keep the engine rpm in peak power range. Thats somewhat easy to do once the quad is up to midrange speed or higher. But, clutch setups that can quickly get the motor to peak power rpm from a dead stop and then keep it there with the least amount of rpm fluctuation will get down the track faster than those that don't. Now, the amount of total weight that you are trying to pull down the track will have an affect on that adjustment - and I'll agrue that till I'm blue in the face. You make clutch adjustments when you change gearing or tire size, don't you? Same concept.

Secondly, call up any reputable engine builder / parts provider and ask them for a rear spring. The first question they'll ask you is -"Whats the weight of the rider?" Ummm, why would they ask that, if it doesn't matter?

I'm not judging anyone by post count or any other criteria, I'm just trying to state my opinion. I used to have notes from an entire weekend of trial and error. We had dozens of clutch parts and graphed computer timed runs based on a variety of ramp angles, roller weight, stall rpm, gearing and rider weight. If I can find the graphs I'll post them. It shows ,in black and white, exactly what I've been trying to explain.

[bstuart]

mmullins14 - the difference in the setups doesn't have any hard and fast rules. Generally the heavier rider setup has a little lighter roller weight, steeper variator angle and a stiffer torque spring.

[mmullins14]

What are the differences in the two quads you have? You said they were set up very different because of rider weight.

[LT80]

Interesting....
I send my motors out with the same clutching for a 50 lb. rider or a 140 lb. rider.
You tune clutchs to the motor and every motor can be different IMO.

[bstuart]

The heavier rider setup is running 27grams of roller weight, an off-brand racing variator from China and a torque spring marked 90. I'm not sure where I got it, but its noticably stiffer than the Koso 1500.

The lighter rider is running 30 grams of roller weight, a Koso variator and a Koso 1500 torque spring (black)

Both run Malossi kevlar belts and have the same motor mods.

They will run nearly even consistantly when each rider is on their own quad. Switch riders - and the lighter rider will pull ahead four lengths in a 230' run.

[Livin4Real]

Originally posted by LT80
Interesting....
I send my motors out with the same clutching for a 50 lb. rider or a 140 lb. rider.
You tune clutchs to the motor and every motor can be different IMO.

Yeah but everyone knows your not a reputable engine builder Jack :blah:

Seriously though, as Jack said, the clutching is built around the motor.

[i-zapp]

Originally posted by bstuart
The objective is to keep the engine rpm in peak power range. Thats somewhat easy to do once the quad is up to midrange speed or higher. But, clutch setups that can quickly get the motor to peak power rpm from a dead stop and then keep it there with the least amount of rpm fluctuation will get down the track faster than those that don't.
Agreed!


Now, the amount of total weight that you are trying to pull down the track will have an affect on that adjustment -
Only in the sense that you need a rear clutch spring that will supply enough axial load to keep the belt from slipping. more spring will require a higher roller weight to maintain that ideal engine rpm. whether it's an uphill or downhill, 60 lb rider or 160lb, the motor should be pulling the same rpm.

You make clutch adjustments when you change gearing or tire size, don't you? Same concept.

I don't. and cant understand why you would. the motor and clutch can't appreciate the RATE of acceleration (rate of change of rear clutch rpm). all these systems can understand is engine rpm and engine torque, which has nothing to do with gearing, rider weight, or track layout.

Again, my position is that once you've determined a perfect setup for the MACHINE (engine and clutch), that's as good as it gets and needs no further adjustment based on rider weight or track. The idea is to hold the motor at peak power (rollers) without the clutch slipping (rear spring). All a heavier rider or steeper hill should do is take longer to get down the track.

Having said all that, i did learn something important this weekend about rear clutches (i think) and that is running too soft a spring on really demanding tracks like HighPoint can cause a clutch to slip after it gets hot. this causes the spring to get hot and soften further, exaggerating the problem further. point? my rear srping was too soft, not because the track was too extreme but because it wasnt correct to begin with.

[LT80]

I don't think the belts slip.
I consider the heat to come from the rear shoes slipping. The simple "is it" answer would be to touch the rear hub after a race/hard yard laps/etc. If you cannot hold your hand on it for a few seconds, there is a heat issue with the rear pads slipping.
Since learning my new rear shoe mod (LT80), I can burn up and down the road and still put my hand on the hub. I could not even think of touching it before. Since then, great holeshots and NO torque spring pancaking.
TT racing can teach you so much!

"You make clutch adjustments when you change gearing or tire size, don't you? Same concept."
Maybe so if going from MX to TT. A huge gearing difference would require a lighter roller weight. remember, you will not spin at the TT start like in a MX start.

Another thing: I don't think a CVT can be set up on a dyno. The CVT acts different on the dyno compared to dirt. We set one up on the dyno for max HP. On the ground it was a turd.

Good thread. :)

[wvspeedfreak]

Since we have some good cvt guys here.......I have a question :)
I just replaced the rollers in our 70cc Kasea.Just routine maintenance,a couple of them were getting light flat spots.I put all new rollers in of the exact same weight that I took out.Now when he punches it from a stop(like leaving the gate) the motor revs up like it is spinning the tires(for a second) but its not spinning,then it takes off like a rocket and tops out nicely.Is it possible the torque spring could be weak and collapsing for an instant causing the initial slip?It wasn't doing this before :confused:

[ww228king]

Mine was doing the same a few months ago and it was the dang clutch bell making the clutch slip. I noticed on mine, when the rear torq spring starts to give, it bogs on the start then take off.

[etondaddy]

What your describing sounds like a big spring to me. It sounds like when Kyle would up hill jump and land it would sit there for a second and then take off. I solved that by changing the spring every six or so races and its never done it again. Knock on wood.

Mike Kozura

[wvspeedfreak]

Originally posted by ww228king
Mine was doing the same a few months ago and it was the dang clutch bell making the clutch slip. I noticed on mine, when the rear torq spring starts to give, it bogs on the start then take off.

That could be it.It is definately something slipping.

[wvspeedfreak]

Originally posted by etondaddy
What your describing sounds like a big spring to me. It sounds like when Kyle would up hill jump and land it would sit there for a second and then take off. I solved that by changing the spring every six or so races and its never done it again. Knock on wood.

Mike Kozura

The quad will rev up and the rear clutch engages and the quad starts to move.As soon as it starts to move it revs up like something is slipping and then it takes off great.All of this happens very quickly.He was doing it in the grass at first and I thought he was spinning for a second.Upon closer inspection,it wasn't spinning :p
I should probably just replace the whole rear clutch assembly.It has countless hours on it anyway LOL.

[etondaddy]

Is the rear clutch stock ? For about $230.00 to $250.00 I can get you a h*ll of a rear clutch setup. The same thats in Kyle's. Let me know.

[wvspeedfreak]

No,it's not stock.I had an issue one time with tranny cover bolts backing out and oil got on the clutch shoes.I cleaned everything up and it was fine but maybe it overheated the bell when it was slipping from the oil being on it.I have also had to lightly sand the clutch shoes a couple times to get all the residue off of them.Also,it has the white torque spring which I believe is the 50cc spring.I may need one heavier.But like I said,the weird thing is that it wasn't doing this before so I don't know :ermm:

[etondaddy]

I wish I had a buck for everytime these things made me ask why…….. I’ve had my head in my arms on the side of the house asking why, I’ve been on my knees in the middle of the yard screaming why, I’ve worked on it for twelve hours on Saturday and never got the little whatever it was out of it and went to the track on Sunday and it was gone and he ran great. I guess what I would do next is put the old rollers back in and see if it still does it. If so I would go with Malossi delta fly clutch, all red Malossi springs, and a Koso bell. Malossi Kevlar belt and Koso 4.2 rollers and a stock e-ton vareator . With a Malossi single ring 70 jug and a Hetrick pipe Kyle’s 70 frickin ran man. I guess I forgot about the full round racing crank from Kool Kidz ATV. Let me know what’s up.

Mike Kozura

[Nocomment]

Okay, heres is what i did and all you Clutch guru's let me know what you think.
I bought the Hetrick National mod which is a Koso rear clutch and oem front Variator (modified) I installed it right as it was sent. Hit the gas and it just sat there and did nothing for a good 3 seconds then started to move slowly.and then took off just okay. I took it all apart and checked everything, all looked good. I changed the rollers to different sizes from 4.5 to 5.5 and no difference. My stock setup launches great (stock clutch drilled out and red springs all around. 5.0g rollers) I weighed the shoes and found stock shoes drilled out weighed 139g and the Koso shoes are 78g I called Hetricks and they were very nice but kinda baffled why it didnt work. they think I should change to the blue springs in the rear. Any one have any Ideas? I put the stock setup back on for the race and ran that but we have a race Sunday and would love to use the new setup.

on another note, I think this is a great thread, such a wealth of information from everyone. Thank you all

[etondaddy]

I would try putting all the red springs in the Hetrick clutch. And I’ve found the stock e-ton variators to be the best. Hetrick hogs out the end of the Kasea variator ramps for more roller travel. I guess they work in some applications. But that’s for top end speed that’s not your problem. If you lowered the roller weight and it still does it I also would start looking in the rear. Try a combo of your stuff and Rich’s stuff to help narrow it down. Good luck.

P.S. If you find yourself in the middle of the yard screaming why…………….. your not the only one my man. lol

Mike Kozura

[mmullins14]

It sounds to me like the rear torque spring is to soft and letting the belt drop in the rear pulley to soon. That would be like tring to take off in a very high gear. The other thing is to make sure the spacing is right on the front variator. Make sure when the engine is not running the belt will sit all the way down in the front variator and all the way out on the rear pulley.

[Nocomment]

I did notice the belt seemed kinda loose in the front pulley, the belt had about a 1/8 tho a 1/4 clearance at the bottom. The rear pulley has a black Koso spring so I was think about putting the red springs in the rear clutch

[mmullins14]

I wouldn't change the stall springs yet. The Koso torque spring is a good one. Is it a 1500 or 2000. If your belt is not sitting all the way down in the front pulleys, that is most of your problem. Is there a shim anywhere on your front variator?

[Nocomment]

it does sit all the way down in the front, the gap is on the sides of the belt. Chris at Hetricks said at idle the rollers would move enough to take up the slack.

[i-zapp]

Originally posted by Nocomment
... Hit the gas and it just sat there and did nothing for a good 3 seconds then started to move slowly.and then took off just okay. I took it all apart and checked everything, all looked good. I changed the rollers to different sizes from 4.5 to 5.5 and no difference. My stock setup launches great ...
OK, from a purely thermodynamic standpoint, if you pin the throttle and the machine is not moving, then the power produced by the engine (say 10hp, or about 7500watts) is doing something other than accelerating the vehicle like it's supposed to. that 'something' is producing HEAT, alot of it. So after your test i would immediately check all the parts of your clutch system - the variator, the rear sheaves, and the clutch bell. Something has got to be extremely/unusually hot due to slippage.

Another question to ask is - what is the motor doing during this time- my guess is it's revving like crazy (if you got the throttle pinned). if so, it's could only be the variator if something is limiting its movement (jammed, bound). if your rear sheave has decent tension, it can't be your problem at the bottom end. last item to check is proper movement/engagement of the rear shoes on the bells. make sure its not binding.

if instead the motor immediately bogs or doesnt rev out completely when you pin it i would be suspect of a weak rear spring.

[Nocomment]

It is the latter, when we pin it the motor which is usually very peppy, it just boggs down and slowly comes up to rpm as the bike starts to move. Do you think its possible for the rear spring to be to weak right out of the box?

[i-zapp]

if you can barely install the belt on the rear sheave, then the spring is prolly ok. if you can easily squeeze the sheaves together that may be it. the last time i replaced my black koso spring i needed help. :scary:

[mmullins14]

If it is a 1000 or 1500 spring it may be to weak. A 2000 Koso should be as stiff as you would need to go.

[Nocomment]

The spring says Koso 1500 on it, is the red spring 2000?

[mmullins14]

The Koso 2000 is black. Some of the cheaper red 2000 springs will fatigue quickly and you may be worse than when you started. They weaken even quicker if they get hot.

[newnick]

Originally posted by Nocomment
It is the latter, when we pin it the motor which is usually very peppy, it just boggs down and slowly comes up to rpm as the bike starts to move. Do you think its possible for the rear spring to be to weak right out of the box?

Your variator is most likely binding.

[BradLoomis]

Check the bronze bushing inside the roller sheave of the variator. I think it might have seperated itself from the aluminum housing and is not spining/sliding smootly on the variator steel sleeve.

Usually when the rear spring is weak the bike surges very hard form the belt being jerked into the rear clutch and then popping back out. It is often mistaken with the chain skipping over the rear sprocket teeth.

[03sp500]

In what respect, should I look at the rollers/ramps or the pulley half sliding on the sleeve ?

[drr5]

what causes premature belt failure?

[newnick]

Originally posted by Nocomment
it does sit all the way down in the front, the gap is on the sides of the belt. Chris at Hetricks said at idle the rollers would move enough to take up the slack.

This is not correct, you should call them back and talk to someone else. With this setup your using some of the available travel of the variator before the quad begins to move and the belt more than likely is not travelling to the top of the variator when wide open.

[Nocomment]

We only ran a short distance while testing them, we knew it wasnt going to work, but i did notice there was only wear marks about 1/2 way up the front pulley. Maybe that is the whole problem.

[newnick]

I agree, there's an issue with either the belt being used or the spacing of the variator.

[Livin4Real]

An easy way to check belt travel is to take a sharpie marker and draw 3 or 4 lines spaced apart from the center of the variator to the outer edge, do the same for the rear sheeve. Ride the quad around making sure to get it pinned a time or two then pull the cover and see how far up from the center of the variator and rear assembly the marker is worn off and that will tell you how high up your belt is riding.

[bstuart]

Jack - tell me Moore about your clutch shoes/bell mod. I seem to always have issues there. Pm me.

btw - I was talking about going from woods to TT on the gearing/tire size topic. Big difference between 18" - 12" tires and a 2.15 - 1.14gear ratio. I've always benefited from adjusting the clutch to that switch.

[bracey]

would like some advice on a clutch set up well here my problem i have been running the same set up for 2-3 years we went from great holeshots to mid-pack to back of pack and we are running most of the time the fastest mph and a lot of the time the fastest lap times but because of the poor starts not quite getting all the way to the front 2cd 3rd would like to to do better and think we can the ridder has got a little heavier like 15 lbs iam getting a lot of heat on the clucth drum here is what i got frc clutch red big spring stock front variator 4.2 rollers stock polaris belt and the stock frc springs in the clutch and i have put this in all new still the same result anyone got any help thanks

[etondaddy]

Sounds like the boys have raised the bar on ya. Your turn. Dude I’m going to tell ya what I tell them all and I swear by it. First of all you have excusive heat so the clutch is slipping. This is what we use Malossi delta fly clutch, Malossi big red spring, Malossi little red springs, Koso posi-grip clutch housing, Malossi Kevlar belt, stock e-ton vareator, Malossi 5.4 roller weights. Like they said before the rider weight should not mater that much as long as the clutches are tuned to the motor. We take the clutches apart after every race and check and clean. And freshen the top every 3 to 4 races. Just my option hope it can help. Believe me I know how it gets when they’re not right. I’ve been in the middle of the yard on my knees looking up to the ski screaming WHY………WHY. And then I’ve been in my chair in the pits after a second place in his first national drinking a beverage proud as h*ll.

[newnick]

I've been trying to figure that out myself this year. The one race that we had a breakdown my son jumped out with his first holeshot in a while, was just like it used to be. If I remember right it was very cold out and I'd went thru the trans real good before the race, so I'm not sure if it was because we were little leaner on the jetting or if I'd done some magic in the trans. The very next race he got a middle of the pack start in both motos but had a long run before the first turn and got both holeshots.

[wvspeedfreak]

Ok,I have a question.....would running a stock 90cc rear torsion spring be an ok thing to do on a 70cc quad(50cc with 70cc top end)?Or are the stock springs pretty much junk?It seems slightly heavier than the white spring I am currently running?

By the way,this is one of the best threads I have read in a while.

[bracey]

so where can i get a clutch like the malossi asap and the bell thanks

[etondaddy]

Cory, Kool Kidz ATV you tell that s.o.b Mike Kozura told you to call and you want a deal. LOL LOL Where are ya from ?

[etondaddy]

Originally posted by wvspeedfreak
Ok,I have a question.....would running a stock 90cc rear torsion spring be an ok thing to do on a 70cc quad(50cc with 70cc top end)?Or are the stock springs pretty much junk?It seems slightly heavier than the white spring I am currently running?

By the way,this is one of the best threads I have read in a while.
Jason we ran the same set up on Kyle's 70 last year except for the roller weights we used 4.2's in the 70cc.

[wvspeedfreak]

Originally posted by etondaddy
Jason we ran the same set up on Kyle's 70 last year except for the roller weights we used 4.2's in the 70cc.

Ok,thanks Mike.I just got done installing a stock 90cc torsion spring in our 70,along with a different bell and clutch shoes.That fixed the slipping problem.The bell was definately warped.You could see places where the shoes weren't even touching the bell.

While I was in there I switched the rollers from 6gr. to 4.5gr.Man what a difference that made.I was just doing a little experimenting and I'm glad I did.It launches better and pulls harder all the way to the top than it did before.Now..:D...My next question is WHAT exactly did the lighter rollers actually do to make the quad accelerate better?Do the lighter rollers allow the variator to keep the belt lower in the sheaves longer thereby acting as a lower gear ratio?Whatever it was it helped :cool:

[etondaddy]

Originally posted by wvspeedfreak
Do the lighter rollers allow the variator to keep the belt lower in the sheaves longer thereby acting as a lower gear ratio?Whatever it was it helped :cool:
10-4 you are exactly right my friend. It feels so good when s*it works right don’t it. Glad to here it worked for ya. It may have been 4.5’s I used I can’t remember but I know I used 3.5 for arena cross you should see it jump then. 4.2’s , 4.5’s are good all around rollers. What kind of jug you running I have a used Malossi duel ring man dos it run.

MikeKozura

http://i58.photobucket.com/albums/g278/etondaddy/Malossi_jug001.jpg

[wvspeedfreak]

Mike,we are running the Airsal single ring top end.I have a Koso 2-ring top end here but have never used it.Also,ck your pm's :)

[newnick]

Lighter rollers let the motor rev to a higher rpm before shifting begins. Could give more tire spin, wheellies, better launches, depending on the machine. If the belt travels as far up the variator as it did with the heavier rollers you'll be ok.

[etondaddy]

Originally posted by newnick
Lighter rollers let the motor rev to a higher rpm before shifting begins. Could give more tire spin, wheellies, better launches, depending on the machine. If the belt travels as far up the variator as it did with the heavier rollers you'll be ok.
Bingo, I forget to tell you that get a sharpie marker and mark the pulley and see if your using it all.

[wvspeedfreak]

Should it go all the way to the outer edge?According to my marks it is going about 3/4 of the way up.

[i-zapp]

Originally posted by wvspeedfreak
My next question is WHAT exactly did the lighter rollers actually do to make the quad accelerate better?Do the lighter rollers allow the variator to keep the belt lower in the sheaves longer thereby acting as a lower gear ratio?

Think about it this way... the rollers are trying to fling outward due to centrifugal force, and as they do they push against the variator housing, squeezing the sheaves together. the lighter the roller set, the lesser the force is that's trying to make the gearing taller (moving the belt to a larger diameter), so the effect is a higher engine speed.

and ... that variator roller force needs to be balanced against the axial force exerted by the rear "torsion" spring. the bigger the torsion spring, the more roller weight you need to hold the motor at a given rpm.

the trick is to find a rear spring that provides enough squeeze load to keep the belt from slipping, but not too much to create undue belt tension. then, dial in the roller weight to hold the motor at the peak power rpm. once that's done, only changes to final gearing need be made to accomodate different tracks.:cool:

if lightening the rollers helped the quad accelerate better, it means you've moved the cvt's "shift-speed", or the rpm it controls to, closer to the engine's peak power rpm.

[wvspeedfreak]

Originally posted by i-zapp
Think about it this way... the rollers are trying to fling outward due to centrifugal force, and as they do they push against the variator housing, squeezing the sheaves together. the lighter the roller set, the lesser the force is that's trying to make the gearing taller (moving the belt to a larger diameter), so the effect is a higher engine speed.

and ... that variator roller force needs to be balanced against the axial force exerted by the rear "torsion" spring. the bigger the torsion spring, the more roller weight you need to hold the motor at a given rpm.

the trick is to find a rear spring that provides enough squeeze load to keep the belt from slipping, but not too much to create undue belt tension. then, dial in the roller weight to hold the motor at the peak power rpm. once that's done, only changes to final gearing need be made to accomodate different tracks.:cool:

if lightening the rollers helped the quad accelerate better, it means you've moved the cvt's "shift-speed", or the rpm it controls to, closer to the engine's peak power rpm.

That was a very good explanation.....thanks.

[newnick]

Originally posted by wvspeedfreak
Should it go all the way to the outer edge?According to my marks it is going about 3/4 of the way up.
Yes, you want the full travel.
Like I-Zapp mentioned there are several things that need to be matched or balanced for it all to work together.

[etondaddy]

I had said in one of these post that WE go over the clutches before every race I was wrong HE goes over HIS clutches before every race. I think it gives him a better feeling when he has his hands in it. I like when he’s done he’ll test it in the yard and then he looks at me and says load it up lets go racing………… that is so cool.

http://i58.photobucket.com/albums/g278/etondaddy/IM003975.jpg

http://i58.photobucket.com/albums/g278/etondaddy/IM003974.jpg

http://i58.photobucket.com/albums/g278/etondaddy/IM003973.jpg

[wrhracing]

Originally posted by miniquad
So the clutch set up for a 125 pound kid is the same as a 50 pound kid. If that is the case then there should only be one clutch set up that works for everyone that would be really simple. Does anyone carry this one particular clutch setup if so im interested.
Might as well say that a engine set up in a 90 lb scooter chasis uses the same clutch components as a 258 lb mini quad chasis.
Maybe in a low H.P. engine.
I try to get the most acceleration out of a transmission set up for the miniquads if it's mx. The lowest et's to the first turn. If you get there quicker then the other guy/gal then your in front. I would certainly tune to the track . Uphill, flat, Muddy, Cement start, etc..

Of course having a 21 H.P. 70 versus a 13 H.P. 70 is kind of a deterrent too.
Same goes for the 90's.

[ww228king]

Open CVT In Motion!!!!! (http://www.youtube.com/watch?v=wzdzdUANQ8s&mode=related&search=)

[boomer43]

what do you guys think of dr.pully for the set up on mini quad.

[wrhracing]

I like the sliders they seem to last forever.

[47501exracer]

Trying to build up my daughter's Arctic Cat 90. It is a 2004 model in excellent shape, barely used. The engine takes forever and a day to get the quad going. Among other things such as tires, smaller rear sprocket.....I want to modify the CVT roller weights and rear spring. Where are you all buying this stuff at that doesn't cost a fortune? Thanks!

[47501exracer]

Trying to build up my daughter's Arctic Cat 90. It is a 2004 2 stroke model in excellent shape, barely used. The engine takes forever and a day to get the quad going. Among other things such as tires, smaller rear sprocket.....I want to modify the CVT roller weights and rear spring.

Does anyone know what the stock carb is on this model?

Where are you all buying this stuff at that doesn't cost a fortune? Thanks!

[mmullins14]

Originally posted by wrhracing
Might as well say that a engine set up in a 90 lb scooter chasis uses the same clutch components as a 258 lb mini quad chasis.
Maybe in a low H.P. engine.
I try to get the most acceleration out of a transmission set up for the miniquads if it's mx. The lowest et's to the first turn. If you get there quicker then the other guy/gal then your in front. I would certainly tune to the track . Uphill, flat, Muddy, Cement start, etc..

Of course having a 21 H.P. 70 versus a 13 H.P. 70 is kind of a deterrent too.
Same goes for the 90's.
I agree you set the clutch up for the engine and the power of the engine will matter, but the weight of the rider shouldn't matter. As far as the 90lb scooter, same thing. Add a 170lb adult rider and its the same weight as a quad. And it depends what your going to use the quad or scooter for.

[wrhracing]

If weight doesn't matter than why would the load matter. Or is that what you mean by what you are going to use it for.
I may be wrong or not clearly describing what I am trying to say, but in my back country ways of doing things I do it like this as a example.

A stock Apex 90 and a 45lb kid takes off better than a stock Apex 90 and a 130lb kid. I think by lowering the roller weight the 130lb kid might have a little better acceleration off the line. At least maybe a little better.
That is all I was trying to say.

[i-zapp]

clutch setup is engine specific and has nothing to do with rider or track. some tracks may be more forgiving for the wrong setup, and others may not (like hi point).

if you were riding a streetbike or dirtbike, would you shift earlier or later (rpm wise) depending on your weight? no, you'd shift when the motor fell off the power curve. cvt trans does that for you with the correct selection of roller weights. if your belt slips your rear spring is too light.

over and out.

[Logan #34's Dad]

U just could not help yourself now could you George. Here we go again. LOL

[wrhracing]

I think I would twist my knee on a dirtbike and step off again on a streetbike, but it would be cool right up to the point of soil sampling or the cement poisining.

:eek:

[leadsled01]

Originally posted by 47501exracer
Trying
Where are you all buying this stuff at that doesn't cost a fortune? Thanks! Ya , what he said! Need an inexpensive clutch set up for my 2003 eton viper with hetrick pipe and carb. Any sugestions? Or should I just use the stock eton stuff with different weights and springs? Any help is greatly appreciated. ..

[Nichols Atvs]

Go fast parts and inexpensive in these quads dont go hand and hand . Yes your most inexpensive way is new rollers and springs for NOW!

[ww228king]

do the broke dads mods first and save up...
drill the stock clutch shoes (Hetrick's Mod), take out a few rollers, add 2000 RPM clutch springs and 1500 or 2000 RPM torq spring...

[leadsled01]

Thanks guys! I'll try the mods you suggested and will start saving more money. Jerry

[Whitfield]

Originally posted by i-zapp
Think about it this way... the rollers are trying to fling outward due to centrifugal force, and as they do they push against the variator housing, squeezing the sheaves together. the lighter the roller set, the lesser the force is that's trying to make the gearing taller (moving the belt to a larger diameter), so the effect is a higher engine speed.

and ... that variator roller force needs to be balanced against the axial force exerted by the rear "torsion" spring. the bigger the torsion spring, the more roller weight you need to hold the motor at a given rpm.

the trick is to find a rear spring that provides enough squeeze load to keep the belt from slipping, but not too much to create undue belt tension. then, dial in the roller weight to hold the motor at the peak power rpm. once that's done, only changes to final gearing need be made to accomodate different tracks.:cool:

if lightening the rollers helped the quad accelerate better, it means you've moved the cvt's "shift-speed", or the rpm it controls to, closer to the engine's peak power rpm.


As a newby to Kids quads and the CVT trans,

(Just bought my daughter her first one last week)

I've been searching 2 weeks for this explination.


THANKS !!!

Hey Whitfield try using this web site it tells you everything about the cvt I hope this helps. Thanks Toby http://atv.off-road.com/atv/article/articleDetail.jsp?id=190895

[riding4fun]

Originally posted by BradLoomis
Check the bronze bushing inside the roller sheave of the variator. I think it might have seperated itself from the aluminum housing and is not spining/sliding smootly on the variator steel sleeve.

Usually when the rear spring is weak the bike surges very hard form the belt being jerked into the rear clutch and then popping back out. It is often mistaken with the chain skipping over the rear sprocket teeth.

Brad, would the weight of the rider make a difference. I have noticed that when I test Zacharys quad it will do just as you described. But when he rides it he says it doesnt. 200 lbs vs 70lbs