Seeking Better Understanding of Variator By ellpee (Read 813 times)

[ellpee]

So okay, it looks like I've got my Magnum's high altitude carburetor woes resolved, and the next thing -- maybe not for awhile yet -- will be to tinker with the rollers in the variator to try to get a little more oomph on the many steep hills in our area. I'd appreciate a little "Variator 101" before then to help me understand what I'm getting into. If I have it straight in my mind, lighter rollers will have the effect of keeping the CVT "in lower gear" longer, which is to say more engine RPM, which is to say more power on the hills. Is that right? And what's the tradeoff as far as top end speed? I already top out in the mid-fifties, and wouldn't want to surrender very much of that or I won't feel comfortable on the bigger highways.

[parsonsj11]

buggy parts has a good info page....
.buggypartsnw.com/bpnw-info-center-introduction" rel="nofollow" target="_blank">.buggypartsnw.com/bpnw-info-center-introduction

I've learned a lot from there info pages

[ellpee]

That is indeed an excellent, illustrated explanation of the whole CVT system, and it made me more aware of a possible alternative to lighter rollers/sliders (which, it appears, would in fact cost me some top end). That being, a somewhat heavier main torque spring in the clutch. My initial feeling is that, prior to messing with rollers and giving up top end, I might want to go to a heavier spring. If, as it says, that causes it to "downshift" faster on hills and corners, that's what I think will improve my hill-climbing abilities without costing me highway speed.

I'm "talking to myself" writing this, anybody who sees flaws in my reasoning please chime in. When I get up the nerve to actually get into the CVT, I'd like to only have to do it once if possible (other than future inspection and maintenance, of course).

[alleyoop]

Heavier Contra spring will also require higher rpms to get up to speed and if your motor cannot produce enough rpms you can also loose top end due to not enough rpms to pull the belt down into the lower part of the CLUTCH PULLEY. Also if currently your scoot starts to move say around 2500 rpms with a 1000 rated contra spring it will now REQUIRE around 3500 rpms before the scoot moves on you. If someone is going to put in a stronger Contra Spring and or Stronger Clutch Pad Springs I always suggest the 1000 rated ones otherwise you will not like the high rpms just to cruise around at 25-40 mph.
Alleyoop

[ellpee]

Grrrr, sounds like in reality there may not be a good compromise -- whatever I do has a downside. Well, for right now I don't feel an urgent need to do anything. Start/idle/flat performance is way better than before re-jetting, the rest can wait, and if push comes to shove I may just have to live with a bit less performance in the acceleration/hill-climbing department. Or move to Death Valley, where I'm well below sea level.

I'm thinking when I hook up a tach on the Magnum it will give me a better idea what's going on under various driving conditions, will wait for that (it's on the way, mistakenly had it sent to our winter address so it's somewhere in the USPS forwarding machinery at the moment.)

[parsonsj11]

alley he's talking about torque spring not arm spring.

torque spring makes it harder to pull belt down it works with the rollers or sliders in the variator for gearing.... stiffer spring downshifts better for lower gear while climbing decelerating.. etc...

arm springs have the 1000 2000 3000 rpm ratings......

[alleyoop]

I know exactly what he his talking about and I covered both the CLutch arm springs as well as the Contra spring.

I have done it all, tried different VARIATORS, I even cut down the BOSS I have weights coming out of my ears rollers and DR. Pulley weights. As a matter of fact I have a DVR variator that I have not yet tried. I have a NCY CLUTCH and it came with the 1000 rated Arm springs, I took them out and ordered OEM springs for the NCY Clutch. I did not like that the rpms had to be over 3000 for the pads to be thrown out and grab the bell and the trike start moving. Now I have the trike moving just little over 2000 rpms. I can cruise at low mph if I have to and sometimes I have to when in heavy traffic.
Alleyoop

Alleyoop

[ellpee]

Now you guys are confusing me with terminology. I'm not talking about the three or more little springs that determine how much RPM it takes to throw the clutch pads against the clutch bell, I'm talking about the big central spring that apparently determines how hard, or easy, it is to narrow or widen the clutch pulley. Can we agree on one set of terminology here, even if it's Big Spring/Little Springs? I've asked enough dumb questions here that somehow the forum has declared me a Senior, but I'm still very much a newbie, and things have to be fed to me in small, one-syllable doses.

[alleyoop]

Ellpee,
Same difference bud, just think about it for a minute, by the way that is called the CONTRA SPRING, it puts more pressure on the Belt wanting to CLOST THE PULLEYS NOT OPEN THEM.


So with pushing together the CLUTCH PULLEYS MORE FORECFULLY it take MORE POWER FROM THE VARIATOR TO OPEN THE PULLEY TO PULL THE BELT DOWN. And what creates more power from the VARIATOR MORE RPMS. I do not know how else to make it more clear.

All in all ANY STRONGER spring changes IN THE CLUTCH AREA(WHICHEVER SPRINGS) will require more RPMS to do something.
Alleyoop

[ellpee]

Talking to myself again to get it straight in my mind. As engine revs, variator spins faster. Rollers move outward, how fast and with how much force depends on how many grams. At same rpm, heavier rollers exert more force sooner. Rollers moving out push the drive pulley apart, which is to say pulley diameter gets smaller. Smaller diameter of front pulley and resulting slack in belt allows rear pulley to close (diameter increases); how soon/how fast depends on rating of the "Contra Spring" (see, I got it!). So with front pulley small/rear pulley big, one is in effect in low gear -- lots of rpm at front, not so much at rear. As the scoot gets moving, rpm can drop, which lets front pulley gradually get bigger and rear gradually get smaller, until one is eventually in high gear for cruising.

THEREFORE, a stronger contra spring will resist the closing of the rear pulley longer, requiring more engine rpm, which equates to more power for takeoff and hill climbing. The tradeoff is, first, more rpm at all stages to reach any given "gear ratio," which means more fuel consumption, and higher rpm needed to hold it at highway speed, presumably more wear and tear on the engine.

That's my story and I'm sticking to it. Did I pass the final CVT exam?

[alleyoop]

YOU GOT BUD, Also more chance of the belt shredding and or just breaking because more pressure on the belt creates a lot of heat.
Alleyoop

[ellpee]

Cool, well worth the time spent. Just passed 500 miles (oil change), will probably drive it for the rest of the summer (until October, in our case) and decide whether the hill climbing performance is annoying enough to make me get into the CVT. In all likelihood, will get to maybe 1000 miles in current configuration before October, change oil again, gear oil, pull off the fenders and check everything else I can, and then put it to bed for the winter, to revisit the whole CVT matter next spring.

One thing I would note about the Magnum compared to the Roketa is that the electrical connections seem to be far better. I had issues with bad fusebox connections, light bulbs vibrating loose from their sockets, etc., etc. Nothing big, but annoying little piddly stuff. With Ice Bear and the Magnum, so far despite 1/4 mile of VERY bumpy road between me and pavement every time I ride, zero electrical problems.