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Post by scooter on Oct 7, 2014 21:03:21 GMT -5
I have tried several variators on my scooter and not surprisingly, they are all a little different.
My original gave me somewhat high rpms at top speed, running the motor over 8k a lot, even with 14g weights.
My performance variator gave me low rpms, leading to shaky starts off the line but good overall acceleration, yet too low rpms on top, even with 8g weights. It was hard to get it up to 7,500 rpm. I bought spacers for it but have not used them. Not even sure the variator is okay after using it for a few hundred miles and having a belt failure with mangled rollers but that's another story.
My last purchase is giving me very high rpms, 7500 at 50mph with 14g weights, and I hit 9,000 rpm the other day by accident. I need to close it up. I'm ordering another boss to shave down. I have a little room on the variator diameter, to move up, so I'm going to see what I can do with it. Alternatively I could shave a hair off of the front of the drive sheave where it meets the boss but the boss will be easy to toss in a lathe and face without any hassle.
One thing is for sure, these variators are not all the same at all. It's understandable since quality can vary and a few thousandths of an inch can change performance, but it seems clear to me that modding variators would be a nice way to fine tune them.
If I knew it wouldn't break, I'd like to machine the surface of my sheaves for a custom rpm curve, to get the low end I want and the top end I want too. I could even add a nice top angle to set the limit of how high the belt could go. I believe someone on here mentioned that as a feature found on Dr Pulley variators.
So far, weight changes have been less than satisfactory and are a trade off at best. I figure some of you have modified your variators in some way, by adding shims, shortening bosses, cutting sheave faces, doing custom ramp surfaces, or maybe even bending your steel back plates.
How about it? Any V-Mods going on here?
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Post by scooter on Oct 11, 2014 12:58:08 GMT -5
UPDATE 1 10/11/2014Today I gathered my variators and ramp plates and bosses and took a bunch of measurements. I ran the following two sets with 14g rollers. With my new variator I was getting about 6300 wot rpm at 35mph which ain't bad and 7500rpm at 50mph which is horrible, so I took all of the parts that would make my variator width as thick as possible to drive the belt higher while using a very slightly shorter (-0.004") boss as well. I am now getting 5300 wot at 30-40mph which is too low, BUT I am getting 6500rpm at 50mph and I'm doing 57mph at 7500rpm, instead of 50mph. With a reduction of pulley separation of only 0.037" I was able to make the belt ride about .070" higher on the variator by using my old variator with my new ramp plate and boss. It's not much of a modification but it's effective.
The next step will be to drop the weights some. UPDATE 2, 10/11/2014 10:15 pmSwitched out the 14g weights for 10's, the lowest I have handy. 6100 WOT @ 35mph 6500rpm @ 50mph 7500rpm @ 56mph These are pretty satisfactory numbers. If I drive the belt any higher, I won't have enough power to push it any faster and my acceleration will suffer. I'll lose both acceleration and top end speed. If I make the belt go lower, I'll get better acceleration but I'll rev higher at high speed. I'll gain top end but at the expense of possibly damaging the engine by running it at too high an RPM. Dropping the weights to 8's should bring my WOT up even more while not affecting my top end. I want a sustained speed of at least 55mph without blowing the engine up. Without adding more power to the engine, this is about all I can do. Another variator may have a better power curve but so far I am not getting any measurements with these variators. I just get a variator in a package and a "let's see what happens this time" approach to performance. My ebay KOSO variator had a similar power curve to this setup, with 8g weights, but suffered a catastrophic failure ending in a distorted variator bushing, chewed up rollers, and a mulched Gates Powerlink belt. UPDATE 11:45PM 10/15/2014Ordered some DrPulley 8g sliders. My first set of sliders. I just put the Dr Pulley 8g sliders in my scoot and measured the plate/roller/sheave assembly. The new slider assembly width measures .010" less than the roller assembly, when the rollers/sliders are at the bottom, meaning my belt radius should drop 0.020", increasing off the line torque slightly, BUT, from what I can read of the "marker test", the DrPulley sliders raised the belt radius at top end by about 0.075". That's a huge jump that will lower top end rpm, but also pushes the limits of the engine's ability to move the bike faster. (I'm geared about as high as I can be without losing top end speed.) This setup is giving me 7500rpm@55mph and 6800rpm@WOT(at35mph*).These weights with this current variator are in my sweet zone, as I do most of my driving at 55-60mph. The acceleration rpms rise so fast that the digital tach struggles to keep up. *( I chose 35mph at random because the WOT-RPMs rise, the faster I go, so I had to pick something to use as a baseline to compare different variator setups. I have been using MPH@7500rpm, WOT-RPM@35MPH, RPM@50MPH, and RPM@top-speed as references). I COULD fine tune this with shims, if I wanted to, but really this is an excellent setup. I have the lightest weights I can find, for the best acceleration I can get, and the belt is so high on top end that going any higher would probably net a loss. I will likely try some shims just to get more readings anyway. A small shim could push my WOT toward 7000-7500rpm and might even give me more top end speed at the cost of having to rev the engine faster. But we're probably talking fractions of a mph at this point. Even at high rpms, 60-62mph seems to be about all it's got. Before anyone poo poos the shims, I will leave the following notes. On top end and RPM: Two limiting factors. 1)The first limiting factor is how hard the engine can pull. If the engine is struggling to reach 7500 rpm at top end, then the engine can't handle more load, and making the belt ride even higher, by cutting the boss or unshimming, will actually cause the bike to lose top end. If you are in fifth gear, to use an analogy, and you can barely keep the rpm up to 7500, then shifting into sixth gear is going to lose you even more rpms and speed. 2)The second limiting factor is redlining. If you are struggling at 55mph@7500, and you lower the belt, by widening the variator with shims, your rpms will go up. You will now be able to go faster BUT your rpms will go higher, and you have to decide how many rpms you think the engine can take. Let's say you moved to 55mph@8000rpm and have more throttle to go. Do you really want to wind the engine up to 9000rpm to go faster? You could, but do you want to risk it? At some point, raising the RPMs won't help any more. Even at full throttle, you'll be geared so low that the engine just can't rev any higher or has blown up. Lowering the RPMs won't help either because you won't have the power to push higher gearing. At this point, you are done tuning your variator with weight and shim exchanges.
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Post by alleyoop on Oct 11, 2014 13:12:31 GMT -5
The only thing I tried was cut down a BOSS and put in a different belt but that caused loss of rpms and lower top end speed. Used the original belt but due to the shorter boss the belt climbed to fast up the variator and caused loss of rpms as well as top end speed. Used a longer and smaller width belt and that raised the rpms but loss of top end speed. Alleyoop
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Post by xyshannen on Oct 11, 2014 16:09:43 GMT -5
I think what you are asking is a little more advance than what most are comfortable with doing. These variators only have so much metal and machining them down risks messing with something that has to spin at several thousand RPMs. Then add to that the availability of different angles provided by different manufacturers and then the ability to change how they perform by simply changing the weights of the rollers of sliders, making doing the mods you are talking about out of the realm of common sense for most; But having said that..if you want to be the test bunny by all means go for it! lol
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Post by scooter on Oct 11, 2014 19:03:49 GMT -5
I think what you are asking is a little more advance than what most are comfortable with doing. These variators only have so much metal and machining them down risks messing with something that has to spin at several thousand RPMs. Then add to that the availability of different angles provided by different manufacturers and then the ability to change how they perform by simply changing the weights of the rollers of sliders, making doing the mods you are talking about out of the realm of common sense for most; But having said that..if you want to be the test bunny by all means go for it! lol Thanks. It's not all that complicated to trim a boss. I believe you'll get almost 2 units higher on the variator for every one unit you close the distance between the two sheaves. Trimming 1mm off of the boss will make the pulley go almost 2mm higher on the pulley, adding almost 4mm to the effective outer diameter of the variator where the belt rides. Some people sell shims to lengthen the bosses but if they are too long then you have to cut them or buy them shorter. Ideally a boss would be too short and come with shims. A few thousandths of an inch can make a difference in performance. People spend a good deal of money just to get that edge. Unlike weights, the length of the boss sets the starting and ending diameters of the belt on the variator, given the variator angles available. A perfectly made custom variator could keep a scooter at maximum torque and speed from start to top end. This would be very useful for racers and people who just like performance. I would like to find out how much I can cut off of a variator face without weakening it too much. That would be good to know, and setting custom shift points by adjusting the inner ramp faces would be especially useful. Like yourself, I have done a little sewing among other things. It's not for everyone but if you're adventurous then it can be rewarding to go beyond buying things off the shelf. An online community may attract adventurous people such as you and I and we can share information.
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Post by scooter on Oct 11, 2014 19:44:27 GMT -5
The only thing I tried was cut down a BOSS and put in a different belt but that caused loss of rpms and lower top end speed. Used the original belt but due to the shorter boss the belt climbed to fast up the variator and caused loss of rpms as well as top end speed. Used a longer and smaller width belt and that raised the rpms but loss of top end speed. Alleyoop I see. It looks like you ended up geared a little too high in the first two setups. I'm guessing the second boss is 1/16" to 3/32" (0.063-0.094") shorter than the first one, making the belt go approximately 1/8" to 3/16" (.125 - .1875") higher on the pulley. A substantial jump. The shims I have seen start at .1mm (0.004") and go up to 1mm (0.039") which would raise the belt by .008 to .08 inches on the variator. On the third setup you caused the belt to ride lower in the pulley, so it could not open as much at top speed, and I guess it was not enough to offset the difference in your boss length?
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Post by blue on Oct 11, 2014 20:46:58 GMT -5
I have learned if it not broken dont fix it.
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Post by scooter on Oct 11, 2014 21:11:24 GMT -5
A very popular saying during the Dark Ages.
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Post by alleyoop on Oct 11, 2014 21:47:29 GMT -5
Yep in other words what I am saying do not waste your time with the cutting the boss or shiming up the boss either way you loose top end. I have done so many cvt experiments with weights and sliders and belts and different variators that on my CVT cover I kept only the 4 center bolts to make quick changes. I have tried different performance variators and roller weights 10, 10.5, 11, 11.5, 12, 12.5 and 13s and then the same grams but with Dr. Pulley Sliders. Out of all the performance variators I have tried I like the KOSO. Alleyoop
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Post by xyshannen on Oct 12, 2014 0:11:12 GMT -5
Indeed I agree with trying different boss lengths..Although I do believe Ally should know better. I was more referring to the dangers involved in messing with the face of the variator pulley and the taking away material from something that has to spin at such a high rate, could in some case be dangerous.
Not that I intend to discourage you just offering reason as to why more are not telling you of their attempts at such an endeavor.
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Post by scooter on Oct 12, 2014 4:20:25 GMT -5
Thanks. I agree that he should have known better. Randomly hacking on the boss isn't going to improve performance. It sounds like he didn't put much thought into it.
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Post by scooter on Oct 12, 2014 6:43:54 GMT -5
You obviously cut too much off. Blaming the mod for your mistake is like saying you shouldn't waste your time using motor oil because you overfilled your oil reservoir in a GY6 and got poor results, or that tires are useless because you once tried putting 20" tires on your scooter and it didn't work out.
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Post by xyshannen on Oct 12, 2014 11:44:29 GMT -5
Thanks. I agree that he should have known better. Randomly hacking on the boss isn't going to improve performance. It sounds like he didn't put much thought into it. err lol that's not exactly what I meant. Ally has done pretty much any and all testing in this and should know what he's talking about in regard to messing with your boss length. Honestly I installed the Hoca 115mm Variator and was extremely pleased with the results the first time around. It made my scooter run at a much lower more relaxed RPM at 45 mph and increased my top speed by more than 10 MPH. Having done all the bolt on mods to my engine gave it enough HP that at the lower RPM I still have plenty of pull from the motor if I need to go faster than 45. My engine doesn't sound like it's straining to keep up like it did stock at the same speed. But having said all that...now with the mods I'm currently doing, I know I'm going to have to play with my roller weights vs contra spring to get my engine in it's new torque curve of 6-8k RPMs. But I don't foresee ever having to mess with the bos length to get my desired result. I don't bother with a CVT cover and have extensively watched my belt on the variator and it goes all the way up to the edge of the variator. In fact I fear that if it ever goes any higher it will pop off.
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Post by xyshannen on Oct 12, 2014 11:52:54 GMT -5
In this pic you can see I'm wide open. i1287.photobucket.com/albums/a624/xyshannen1/beach_zps75715cbb.jpgI don't ride in the rain and if I did I'm still not worried. I "might" get a little slipping, but these things turn so fast any moisture will quickly be evaporated off. I only worry about torrential downpours and deep puddles. All of which are easily avoided. And my body work on this scoot keeps your legs at a safe distance.
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Post by scooter on Oct 12, 2014 12:09:35 GMT -5
But having said all that...now with the mods I'm currently doing, I know I'm going to have to play with my roller weights vs contra spring to get my engine in it's new torque curve of 6-8k RPMs. But I don't foresee ever having to mess with the bos length to get my desired result. I don't bother with a CVT cover and have extensively watched my belt on the variator and it goes all the way up to the edge of the variator. In fact I fear that if it ever goes any higher it will pop off. Yesterday, just by shear luck, I managed to put together enough individual parts to achieve a small reduction in the width of my variator, and the results were excellent. My belt rides closer to the edge and my RPM curve is much better. I have taken a special interest in variators and I can tell you that changing the boss length really is effective. There is nothing a contra spring or roller weight can do to adjust belt height. It can only go so high or so low given the dimensions of the rollers, back plates, variator sheaves, and boss length. Once you have enough weight to make it open all the way, no amount of weight is going to make it open any more. Yours is fine, but IF you needed the belt to come down, shimming the boss would be the way to go. But it would be a very small shim, not 1/8", not 1/16", but more like 1/256" - 1/64" or .004 - .015". It would be very easy for someone to overshoot that if they didn't do the math first, and I find a lot of people don't do the math. They'd rather work by trial and error, and that's okay, but can be costly and inefficient. From the picture he posted, I'd say he went too far, and from what he said of the results he got, I'd say he went too far. Alley is a smart guy, and experienced, and very generous, and helpful to everyone on the site, but no one knows it all.
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