17 Gram Roller Weights Seem To Heavy

[MLN]

When I had my Bandit RC-150z scooter torn apart last week I pulled the variator apart to see how it worked. Simplicity is the best way to describe it! While I had it apart I decided to record the roller dimensions and weight. I was surprised to find they weighed .6 ounces which converted to 17 grams. I don't recall ever hearing of rollers that heavy! The highest replacement rollers I can find on the web are 15 and those are rare. Normally it's 14 or less.

I emailed Stan and he suggested 12s for my 200 pound arse. I have 100% faith in his suggestion based on his experience (I have zero experience at the moment) and I'm not doubting his choice. I'm wondering just how much of a change I can expect from my scooter if I go to 12s. That is a 29% weight reduction. It seems like it would make a huge change in the response. I don't have a tach so I have no idea of the RPMs I'm pulling now, I can only asume it will be a lot more with 12s. Would that be correct?

I think the little 150 performs admirably now. However, I'm a tinker and can't leave well enough alone. I see one or two sets of weights in my future.

[mattztt]

I wouldn't expect your peak RPM to go up much, but it will be higher at low speeds and you should have better acceleration.

[Jacine]

Your top end will also go down.

[MLN]

jacine said:

Your top end will also go down.

If the weights are heavy enough to push the belt completely out the top end should be unaffected right? It will just get there quicker right. I don't want to severely handicap my fuel economy. However, my two-up mileage might be better since the engine won't be working so hard.

[sussexscooterhead]

Your top end will NOT go down.

Going to a lighter roller (or slider) will raise the shift RPM of your CVT. Once the variator is completely closed - meaning the 2 halves are touching and the belt has been pushed to it's highest point on the pulley - the weight of the rollers becomes irrelevant.

From that point on, the top speed of your scooter is dependent on it's horsepower, final gearing, environmental conditions and other things outside your control.


I wouldn't necessarily recommend this for anyone else, but I've been running with only 3, 14g rollers in mine for about 500 miles now. I removed the other three just as an experiment and was so happy with how it was working I left it that way. Like I said, maybe not something I'd recommend, but the point is, 3x14g rollers is the equivalent of using 6x7g rollers and my top speed is exactly the same as before. What's changed is how quickly it accelerates.

[mattztt]

Your top end will NOT go down.

Correct. If anything the top end may go up slightly since there will be less total mass to keep rotating. I don't know the math well enough to say if this would even be perceptible, but you definitely won't lose any top end.

[MLN]

sussexscooterhead said:

I wouldn't necessarily recommend this for anyone else, but I've been running with only 3, 14g rollers in mine for about 500 miles now. I removed the other three just as an experiment and was so happy with how it was working I left it that way. Like I said, maybe not something I'd recommend, but the point is, 3x14g rollers is the equivalent of using 6x7g rollers and my top speed is exactly the same as before. What's changed is how quickly it accelerates.

You must have been reading my mind! I was thinking that three 17 gram rollers is 51 grams and four 17s would give me 68 grams. Some guys are running six 9 gram roller which is 54 grams. I might just experiment on my days off if I get my body panels replaced and the valves checked first. I might have a hard time keeping the front end down!!! ;D

SSH, the three 14s give you 42 grams. That seems really light. It didn't effect your top speed? How about mileage(if you're into that)?

Does anyone have any weights I can experiment with so I can determine a final weight? I'll pay for shipping and send them back, I promise!

[sussexscooterhead]

I'm going to get some from these guys for testing:

tinyurl.com/28lj9r


You might want to consider a different spring as well - just to add more mud to the water.

[MLN]

SSH, the three 14s give you 42 grams. That seems really light. It didn't effect your top speed? How about mileage(if you're into that)?

I'll have to experiment. I think ill find a way to mark the belts highest position on the variator. Then I could change weights and see if the lighter weights allow the belt to climb as high. At a certain point the torque spring will be to stiff and need to be lighter. This could end up in a dog chasing it's tail scenerio real fast!!

[sussexscooterhead]

No, it hasn't affected top speed. As for mileage, I haven't checked that in ages but now that you mention it I'll try to pay attention. It surely has to have gone down though. With it being so peppy I tend to ride it harder and that, of course, burns more fuel.

To determine the travel of the belt up the pulley I drew a line with permanent marker on one side and checked after a short ride to see how far up the line had been worn off. The lighter weights didn't affect this - but you'll see that for yourself.

[MLN]

sussexscooterhead said:

To determine the travel of the belt up the pulley I drew a line with permanent marker on one side and checked after a short ride to see how far up the line had been worn off. The lighter weights didn't affect this - but you'll see that for yourself.

That is EXACTLY what I had in mind!

[sussexscooterhead]

Here's a pic from when I did it.

Surprising how far up the belt DOESN"T go - mind you, there is a reason for that.

[bobpt]

The second year after having my first scooter, I decided I had become knowledgeable enough to start doing some simple mods. Changing the variator weights was first on the list. I weight 230 lbs. and decided I wanted to try 10gm weights. I had no idea what was in there to begin with.

I ordered some 10gm sliders from Oregonvintage. I installed them and noticed a significant increase in my RPM at take off, maybe to much. At 35 - 40 mph cruising, it seemed that I was running a 4 speed manual in 2nd gear all the time. I took the original weights to a pharmacy and they weighed 13.7 gm.

I spoke with Stan and he suggested buying 12gm sliders. That way, if it was still to heavy, I could then play with three of the 10gm and 3 of the 12gm to give me 11gm. So I could trial 10gm, 11gm, and 12 gm.

I found that for my weight and scooter, I got the best acceleration and RPM match with the 11gm.

I put my scooter up for sale and I took out the sliders and replaced them with the original 14gm rollers. The difference in acceleration was immediately noticeable. My first ride was to work the following morning after installation and I was thinking my brake was dragging or something until I remembered I had put the old, heavier rollers back in. It took me about 2 weeks to sell the scooter and I kept thinking that if somebody doesn't buy this soon, I am going to put the 11gm sliders back in because I can't take this anymore. LOL

[MLN]

I may buy those cheap rollers you showed me and do some experimenting. Then I will buy the sliding weights once I've made my final decision. I probably should have a tach so I can really determine the changes verses just guessing. The problem is I don't want a Tiny-Tach type tachometer since I really don't have any real estate to mount it. I'd like to find a handlebar mounted tach. I've found some but they max out at 8000 RPM and I think that may be a touch low.

[MLN]

Bob

Thanks for the input!

[bob]

Sussex,
Thanks for resizing the picture. I'm using IE7 and the picture was huge both on my 15 inch laptop and my 42 inch tv. You must have just done it while I was reading this post. It was huge and then I did a refresh and it was back to normal.
Thanks again,
Bob

[Jacine]

Sorry but I tend to disagree. The lighter roller weights tend to decrease top end.
If your roller weights are too light, then there will not be enough force to push the ramp plate out and the rear half forward. This will result in good acceleration, but a low top end. You will simply remain in a low gear for too long. As the engine speed finally gets moving enough to move the pulley forward and raise your gearing, you will be above the RPM of peak horsepower for the engine, and it will not have the power to get you moving.

In fact I will post the full information on how a CVT functions in the General Section.

[sussexscooterhead]

You're kind of talking apples and oranges, Jacine.

While a roller that is 'too light' will, by definition, be too light to allow the variator to shift out before peak horsepower or to shift out at all, to say that a 'lighter roller' will have the same effect is incorrect. A lighter roller is not, in most practical situations, one that is too light.

There are any number of weight and spring combinations Mark can use that will improve acceleration without affecting top speed.

Have you tested your theory Jacine? Can you tell us at what roller weight your variator no longer shifts completely?

[Jacine]

He will have to try trial and error to get the right weight and spring combination. Its not based on the variator shifting, but based on the rpms that the variator will shift at. Remember the engine can only go to its maxed rpms, rev limiter and then that's all there is. If the shifting is too slow by the time the rpms are up there will be no more speed. You can alter speed by changing the size of the clutch cones, which in effect provide larger gears, but there are limitations. Racing variators increase the ramp length and may conceivably add some top end, but generally they just improve overall performance in smoothness.

[sussexscooterhead]

It's all well and good that you've mastered the "cut and paste" response but sometimes a person has to read between the lines and think for themselves.

Posting comments like, "Your top end will also go down." without any kind of explanation and then pasting up an article which you clearly don't fully understand as a way of backing up your position doesn't help anyone.

Please think before making such remarks and in situations where you don't KNOW from firsthand experience, say so. Way too much of this kind of thing happens here.

[Jacine]

Would you like me to supply you with the mathematical equations that support this concept. I usually try to keep things relatively simple, to prevent people from screwing up their bikes beyond repair. However I occasionally do meet those who are so dead set in their beliefs that even an tidal wave cannot move them. I prefer not to take credit for items that are already written, especially since these are neither new conceptual ideas nor do they require the level of Einstein to understand. If you would stop to think, you might realize that RPM is the limiting factor and lighter weights will reach that dead stop rpm before the variator plates have had time to fully open. This in turn will limit the clutch plate movement and result in a lower gear at the max rpm, and a slower bike. And yes I've tried it and lost 2 - 3 mph on the top end, with more of a conceptual improvement in acceleration.

There are a few tricks that malossi and polini use in their racing variators based on the concept that there are a few more rpms in the engine before the rev limiter is reached.

[sussexscooterhead]

Sure! I love math.


So, for the benefit of anyone who has the same model of scooter as you, can you tell us at which roller weight your variator no longer shifted into 'high gear' at an optimum RPM? And for those of us that don't have the same model can you inform us as to the weight of the stock rollers?

[Jacine]

The stock wts for the V3 are 26 gm. I did a Koehler reduction mod to 21 and ended up with rocket take offs, burnt rubber, and a loss of top end of 2-3 mph, plus it took longer to top out. Didn't like the strain it put on the bike so kept the original in. Then again I am far from the 180 pound default wt that these bikes are set at. The bike does what I want, so why tinker with it at this point anyways.

Actually I should let you fight with Stan, who also would tell you that adjustments can be delicate and lower wts can lead to a loss of top end. There are several threads of his that espouse the same theory.

Then of course there is the quote from Martin Performance Racing

"Roller Weights
We highly recommend that you begin by upgrading the variator roller weights before engaging in any performance upgrades. This is the simplest of upgrades and the least expensive for the consumer. We suggest stocking every size for every brand you carry in the store. This is a minimal investment and offers a maximum return.

The main rule for tuning variators is: the lighter the roller the more rpm’s are needed to push the rolls outwards through centrifugal motion to set the gear change in motion. Heavier roller weights need lower rpm’s to start moving.
Heavier roller weights = slower take off speed, more acceleration, = higher maximum speed.
Lighter roller weights =faster take off speed, less acceleration = lower achievable speed.

The right balance is an individual choice since a scooter racer will want heavier weights to achieve a higher overall speed so that they might be faster at full throttle. For daily use a driver might prefer lighter weights for more power to take off faster at a stop light. We recommend you stock all of the sizes for the brands you sell due to the low cost and quick turnover of the product. "

www.mrp-speed.com/store/home.php?cat=266

Anyways nice arguing with you, but you're still wrong.

[mattztt]

lighter weights will reach that dead stop rpm before the variator plates have had time to fully open.

Lighter than what? Just saying that going to lighter weights will lower your top end is like saying that having more rain will cause the dam to flood or that having more money will put you in the next tax bracket. It completely ignores the fact this is a matter of being above or below a threshold.

[Jacine]

Lighter than stock oem that comes with the bike (Based on a 180 wt male)

[mattztt]

jacine said:

Lighter than stock oem that comes with the bike (Based on a 180 wt male)

So you believe that going below oem weight, regardless of the scooter brand and regardless of the actual weight, is going to cause top end loss?

[Jacine]

I am assuming that you are dropping the wts significantly, otherwise why do it?. Therefore dropping from 26 to 21 (non koehler mod) is a loss of 5 x 6 = 30 grams, (koehler mod) = 15 grams. or a 23 gram wts. The reflex K-mod removes 3 18 gram wts for a loss of 36 grams, but there is a loss at the top end, but a great improvement in acceleration and performance through the bands.

[mattztt]

One possibility here is that the manufacturer went way over on the oem weight. 17g is very heavy for a GY6.

[MLN]

Tomorrow I will put the Jacine vs SSH thought process to bed. I'll do a test run with it stock for indicated top speed (sorry, no GPS). Then I'll remove 2 weights and do another speed run. If I'm feeling real giddy and I have the time I'll remove 3 weights. I'll post the results and no matter the result.

Personally I think that there is a golden weight that will still clamp the variator halves completely, allow better acceleration not take away any top speed. Like all things, there is a point of diminishing returns and you end up with Jacine's point of view.

Also, in Jacine's example of the V3 we are talking a bike produced by and for CFMoto only. They very well could have tested and found that "golden weight" and used it as stock. Anything less could be a compromise.

All the generic Chinese scooters on the other hand may not have had as much testing and could use a less than ideal weight set. I mentioned it to Jim at Bandit and he sounded as surprised as me. So I don't think he selected and particular weight for his RC-150s. I think they come with whatever the manufacture of the engine assembly puts in them.

[sussexscooterhead]

Like I said, being the queen of cut and paste doesn't do anyone any good, it just makes you look bad.

You know, I kind of feel bad for seeming to come down on you so hard - maybe it's the rain - but this kind of thoughtless reiteration of nonsense is what keeps this forum going in circles.

Just because MRP's webmaster cut and paste some bogus info about roller weights doesn't make it true.

Look at it this way, if you're driving your stick-shift, ford ranger with the gas pedal to the floor and shift gears at 3000rpm you will eventually get into 5th gear and from there continue to accelerate to the ranger's maximum speed.

Likewise, if you are driving the little old ranger with the gas pedal to the floor and are shifting gears at 6000rpm you will eventually get into 5th gear and continue to accelerate until you reach the ranger's top speed.

Obviously, in the second scenario you're going to reach that maximum speed more quickly but it will still be the same top speed.


Now there are 2 cases in which the ranger won't reach it's maximum velocity:

1) It never gets shifted into 5th gear
2) It gets shifted into 5th gear at such a low engine rpm that not enough power is being generated to continue accelerating

The CVT on our scooters is set up to do the shifting for us but the outcome is the same.