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Post by varroa on Oct 16, 2007 8:38:32 GMT -5
so, ok. here is a logic hole in your logic.
here is the truth: the gearing of the variator does not depend on the load or weight the scooter is carrying.
here is how: the gearing is the same, but in your example, when a rider goes from the hill to a flat ground, it's not the variator that determines the speed increase. it's the engine. our engine only has 50cc, so when a heavy rider is going uphill, it only has barely enough power to spin at 6000 rpm. when he goes on flat ground, engine is able to spin more, thus increasing the forces pushing the weights, so the variator upshifts.
the load puts equal strain on variator and rear spring, so it's all the same regardless of the load.
to really figure this out, you need: a) tachometer, b) dyno machine, so you could tell what speed your wheel is spinning at. after measuring the revs at different speeds on a dyno, you go to flat ground and hills and compare. it will be the same. imho.
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Post by chanito on Oct 16, 2007 12:48:34 GMT -5
A CVT that automatically downshift with load is a transmission engineer "wet Dream" the transmission used on cars (by Nissan) have a complicated set of sensors and a dedicated ECU (electronic control unit) to control the pulleys to make the transmission downshift due to load On our case (ruckus/Metro), what happens is simpler, bare with me, English is my second language (i hope DD can come later and explain it better), lets suppose you are riding along on a flat road and the scooter rollers are at their most outward position, and you start going up hill, the extra load put on the engine, will make the engine have a hard time, as the explosion cycle will have a harder time pushing the piston down with all the extra resistance the load is putting on it, this will raise the temperature in the combustion chamber higher, so combustion will happen faster, being over way before the piston is all the way down, wasting part of the expansion stroke, this will also make the engine produce less vacuum, so the carburetor diaphragm will drop down a bit allowing less gas and air from entering the engine, all of this will made the engine slow down, and if the rear variator spring is doing its job, will close the rear pulley, changing the ratio to one that will allow the engine to suffer less. If the transmission could close by itself it would allow the engine to stay at 8k and the speed would not go down so dramatically
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eq
Junior Ruckster
Posts: 74
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Post by eq on Oct 22, 2007 16:20:25 GMT -5
Now that I've had a chance to get back on my scooter and test for sure what I was explaining, I can add a couple things. Up hill at 6500 RPMS I could do 27.5 mph, down the same hill at 6500 RPMs I could do 35mph, and on flat ground at 6500 I could do 31mph. I don't see how that's possible without the gearing changing with respect to load.
Certainly there's a limit to how much the variator can respond to load by 'upshifting' or 'downshifting'. Also, as I tried to imply before, it's probably better to describe it as 'failing to upshift/downshift': "A heavier load means more resistance, and more resistance causes the variator to downshift, or perhaps fail to upshift, as much as it would with a light load, say a light rider or traveling down hill..."
Perhaps it's true enough that at top gear with rollers all the way out, the variator doesn't respond like a rider would and downshift dramatically. But i think it does respond with some downshifting - independent of engine speed. If someone can explain to me how I could be traveling at different road speeds at the same engine speed - without having the gearing being different - I'm all ears...
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Post by varroa on Oct 22, 2007 17:51:50 GMT -5
so you got a tach? what brand and how much?
chanito, what do you have to say? you have a tach, too, right? do you experience what he says?
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Post by chanito on Oct 22, 2007 18:58:51 GMT -5
so you got a tach? what brand and how much? chanito, what do you have to say? you have a tach, too, right? do you experience what he says? Yes i have a tach, with direct reading, which is what you need to do statement like that, more than likely his tach has what is called a refresh rate (most digital tachs do it), so it takes a reading every so seconds and displays it for that amount of time until it get another reading, the info is still helpful but since it is not right now, is not as reliable as an instant tach. When you are accelerating the rollers are moving against the ramps, if you do it uphill the engine will gain speed slower and the rollers will also open slower (inertia doing its job), so the opening of the roller will lag behind the engine speed, so even though the engine speed is the same the rollers have not open the same and the gearing is different, but as the engine speed stabilizes the roller will catch up and the speeds will be the same, on a flat road the rollers will move accordingly to the engine speed so the readings are accurate. On a down hill the engine will accelerate (gain rpm) faster and that will shoot the rollers farther out, So yes acceleration or rate of speed increase will affect the gearing, but as the engine speed stay the same for a while the rollers will fall back into place, as inertia will slowly became less of a factor. To summarize, if i have the engine and a variator accelerate at different rates to say 6000 rpm, the slower the acceleration rate the harder will be for the rollers to start moving out, so0 if we have a dyno and take speed readings at set rpms and time we will notice that the faster accelerating engine/variator combo will have the rollers farther out at the 4k mark and got there faster, and will reach the 6k mark also quicker, and the inertia will shoot the roller out farther, the slow accelerating engine will have the rollers way inward at 4k and be still be behind the rest position at 6k, now once the engines gets to 6k and stay there, the faster engine will have the roller move back into the set position, and the slower engine/variator combo will have the rollers eventually get there also, so inertia plays a big factor on this kind of games, but the fact will remain that variator gearing is still a function of engine speed. Hope my English was good enough so i did not confuse you more
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Post by varroa on Oct 22, 2007 20:27:16 GMT -5
no, you didn't confuse me, chanito. so, to sum up everything so far, this is how it goes: a variator will have the same gearing at the given rpm regardless of load. however, when engine is under load, the speed at which variator shifts will change, but not the gearing itself. i think, that makes sense, because if you are going about 25 mph (still in such rpm range that with 5.5 g weights the variator should not be fully open) on a flat road and then suddenly start going uphill, variator doesn't downshift when speed drops, instead, rpms gradually decrease. but anyways, ed has a valid point, but i think this discussion can only be proven using a dyno.
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eq
Junior Ruckster
Posts: 74
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Post by eq on Oct 22, 2007 20:46:32 GMT -5
Yeah, I have a tach and realize there's a lag. But it's not hard to hold speed constant at a particular engine speed and look at the speedo, up hill down hill, whatever. These readings aren't about acceleration...
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Post by chanito on Oct 23, 2007 18:44:56 GMT -5
Maybe i am wrong, but downshift is done by the rear spring, and upshift by the engine speed moving the rollers, i fail to see how the load can influence the rear spring
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luke
n00b Ruckster
Posts: 0
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Post by luke on Dec 26, 2008 7:45:42 GMT -5
hi
i have a piaggio nrg extreme it is 8 years old now but still in good condition for the age i have owned it for about a month now and have been riding it every day. a couple o weeks ago i decided to take a look at the drive belt to see how much life it had left in it and could instantly see i needed a new one. i ordered one as soon as i got home that night but before it arrived in the post it snapped on me. the next day my drive belt arrived and i fitted it straight away but in the process i noticed my rollers had huge flat spot on them. fitted it all back together with the intentions of buying new rollers asap. on the way home it ran more or less perfectly but a few metres from my house the speed suddenly dropped and stuck at 40mph then just cut out and would not start again.
i thought i had snapped my belt again but got home and took the engine cover off and all looked okay.
now it starts and goes but as soon as i reach 30mph it just does the same and cuts out..
is this because of the rollers being so worn?
or do i have a more serious problem?
cheers luke
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Post by Dandy Dan on Dec 30, 2008 0:24:23 GMT -5
Most likely you put something together wrong. Your variator nut may have come loose and it's not functioning properly. The variator might not be on tight so it's revving super high and hitting the redline and then stallling....i dunno. The weights should be replaced but they shouldn't cause a sudden problem....they cause a slow deteriorating problem.
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Post by scooterbill on Mar 24, 2009 22:56:40 GMT -5
To know what you need to do to get better performance from a variator, you need to know how it works. So when you know how it works, then you can make adjustments to get better performance from it. A lot of people change things and really do not know what their doing. To help you make good changes, you have to know what each change does. You need to make one change at a time, to know if it helps or not. Here are what each part does: The driven clutch (the one that is attached to the gears in the gear case) has a big spring in the center and 2 or 3 smaller springs that are attached to 2 or 3 brake shoe looking things: The smaller springs are used to decide when the clutch engages and the scooter takes off. The stronger the spring, the higher the engagement rpm is. Those springs do not have anything to do with the the variator, only the engagement rpm of the engine. The big spring in the center of the clutch down shifts the variator and decides how long it stays in a lower gear. The stronger the spring, the faster it down shifts and the longer it stays in a lower gear. I think heavy people need a sronger spring in the center of the clutch to help them go up hills better. Having a spring to weak would be like missing a gear on the down shift. The drive clutch (the one on the enginge) shifts the scooter to a higher gear: The roller weights decide how fast it shifts. The heavier the weighs, the faster it shifts to a higher gear and the lighter the weighs the slower it shifts. The weights also decide how fast the engine can rev to. The weights also need to be heavy enough to get it into the highest gear. The driven clutch has a ramp on the side of the pulley, (not sure what it does) and you cannot change it, so we do not need to worry about it. The variator has ramps that the weights ride on, we can not change them so we do not need to worry about that. The smoothness of the ramps has something to do with how smooth it shifts, the smoother the better (I think that is why some people say the stock variator is better) . The dia. of some variators are bigger than the stock one, so it should have a higher gear ratio. To use that higher gear, we need a slightly longer belt (that may be why some people say the stock belt is better, it streches and therefore is slightly longer). Shaving down the spacer will gear it higher (it is like putting a higher gear in the differenial case of a car).
To tune the variator, what do we do first?
1. The engine needs to run the best it can. Tune the engine FIRST!!!
2. Replace any worn parts of the variator and clutch. Use a scotch brite pad to take the glaze off the pulley faces and clutch bell and acetone to clean oil off the belt, pulley faces and the outside of the spacer.
3. We need to keep the engine in its power band so I think we need to raise the clutch engagement first. We do that by putting stronger springs in the clutch.
4. The clutch spring in the center of the clutch needs to be heavyer, to help with hill climbing and take off power.
5. We need to use lighter weights in the variator to raise the engine rpm on take off so it does not bog down on take off.
Remember!
1. Too light of weights it will not shift into the highest gear and shift to slow.
2. Too heavy weights it will shift to fast and not have good acceleration.
3. Too stiff of engagement springs and you will not be able to use all of the power band and the engine rpm might be to low to for the clutch to stay engaged.
4. To weak of engagement spring and it will take off to soon and not accererate good.
5. To stiff of center spring and it will shift to a higher gear to slow.
6. To weak of center spring and it will not down shift fast enough and bog going up hills.
Mods.
1. Shaved spacer. Shaving the spacer will make it have a higher gear. It is like putting a higher gear in the differential of a car. It would work better with the big bore and higher engine engagement springs.
2. Variator. Some variators are better for accerating and some are better for top end.
3. Clutch. A 3 shoe clutch is better than a 2 shoe because it will not slip as easy.
4. Gear box. You can change two of the gears to make it go faster. It is like putting higher gears in the differential of a car.
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Post by ruknroll on Apr 22, 2009 0:04:28 GMT -5
one thing i have not seen anyone discuss is if you can shave the spacer and also get an aftermarket variator, if that would give you more top end from shaving the spacer but also acceleration from another variator?
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Post by scooterbill on Apr 22, 2009 15:56:55 GMT -5
Shaving the spacer has been discussed on here already. You can shave the spacer but no shorter than 35mm. If you shave the spacer you have to shave the stationary pulley on the variator too. Shaving the spacer is like starting of in 2nd gear in a 6 speed transmission. The aftermarket variators which you can buy is like having a 6 speed transmission instead of a 5 speed. Please search for info first before you ask something, most questions people have will already have been discussed.
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Post by Andrew westside on Nov 6, 2020 7:11:51 GMT -5
Does the belt shift sideway when it's climbing the outer variator?
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Post by Baizy on Nov 10, 2020 0:25:40 GMT -5
Does the belt shift sideway when it's climbing the outer variator? Yes and no. If both the inner and outer drive faces have the same angle relative to the belt it will remain centered over the bushing, however if the variator has a steeper drive face it will push the belt over towards the swingarm cover to a marginal degree. You're unlikely to encounter a variator with a shallower drive face than stock but the belt would move towards the crankcase with a lower drive face angle. Hope that explains it well enough for you.
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