Yuminashi variator and belt

[mikelx5]

ok im confused y would you go lighter for top speed. from reading alot on the small cc scoots i have found you go lighter when you want rpms to go higher becuase the lighter the rollers the more force(rpm) it takes to kick all the way out. meaning going lighter will just increase the rpms past the powerband. now that being said the higher you go the faster the vario pops open meaning top gear faster, unless its too heavy and you dont have enough power in the lower revs.

[wingz]

ok im confused y would you go lighter for top speed.

Who said that?

The NCY video was with 13g rollers. Changing exhaust does not change the rev limiter you are correct. It does however change the tune with the variator. It means I probably need lighter weights to correct my issue; pending top speed changes with the stock pipe.

I don't understand how changing the exhaust would affect the variator.

[Mgalutia88]

Yes it is their speed booster. Start at yuminashi global to look at the products then go to links for a list of distributors.

On the rollers, I just remember seeing different weights suggested for variators depending on if there was an aftermarket exhaust or not. Here's my thoughts. The more power you are making, the quicker the variator will be thrown out so you drop weight, usually a two gram suggested difference, to slow the opening of the variator.

[wingz]

I see you were right in your previous post (dropping weight when changing back to stock exhaust).
More power applies more torque to the rear pulley which lowers the gear ratio (allowing the engine to rev higher in that instance). Heavier weights would counteract this effect.

IINM, AIUI your latest post should read "The more power you are making, the slower the variator will be thrown out so you increase weight, usually a two gram suggested difference, to slow the opening of the variator."

[Mgalutia88]

Wingz, you drop weight with an aftermarket exhaust to extend the gear ratio. The longer the variator takes to be thrown out the higher speed you reach when the variator gulley extends. More power with the same weight (torque) will extend the weights faster. You drop weight to counteract this effect.

[wingz]

Wingz, you drop weight with an aftermarket exhaust to extend the gear ratio. The longer the variator takes to be thrown out the higher speed you reach when the variator gulley extends. More power with the same weight (torque) will extend the weights faster. You drop weight to counteract this effect.

I totally don't understand what you are saying.

Maybe a problem in translation...
If I paraphrase what you said, it reads "You [use lighter rollers/sliders] with an aftermarket exhaust to [increase] the gear ratio. The longer it takes for the [rollers/sliders] to be thrown out, [increasing the gear ratio], the higher the speed you reach when the [rollers/sliders are as far out as they will go]. More power will with the same [mass rollers/sliders] will [throw the rollers/sliders out faster]. You [use lighter rollers/sliders] to counteract this effect."

The above explanation is opposite to what makes sense to me.

Doesn't the following make more sense?
More torque on the rear pulley brings the rear pulley halves closer together. As the belt moves outwards on the rear pulley, the front pulley halves are pushed apart.
The combination of front pulley halves moving apart and rear pulley halves moving together lowers the gear ratio and increases rpm.
To counteract this, one installs heavier rollers/sliders which push the front pulley halves closer together forcing the rear pulley halves further apart.
This increases the gear ratio and decreases rpm.

[Mgalutia88]

All torque comes from the front pulley though and the bigger the front and smaller he rear the higher your ratio. More engine power makes it easier to throw out the variator weights faster. You want the speed your weights are being thrown out to stay a constant for high speed ability. Think abou centrifical force. If you have a heavy weight on the end of a string and you spin in a circle it takes little force to make the string taught. If you reduce the mass of that weight on the string you find you need to spin faster to make the string taught. It's the same theory as power in our scooters. The more power the engine makes the lighter we want the rollers to be because we want the string to become taught at the same time. If it becomes taught too soon then your top speed is decreased. Engine rpm I when the variator is changing is a constant.

[Mgalutia88]

This is a quote from webike on the takegawa variator found here.
http://japan.webike.net/products/20129423.html

■ PCX-replacing the normal and only about 10% of the maximum speed up available High sped Puri Kit This calls for a. Is SP takegawa's recommended weight roller bolt design, suitable for normal muffler fitted ( 10 g x 6 ) because comes with no need to separately purchase parts enjoy. You can enjoy further performance changes in Use have you to fit prepared are pleased to also separately (8.5 g) to the use SP Takekawa, Inc. silent sport muffler on a weight roller best person further best to further your silent sport muffler with SP takegawa, Inc. (8.5 g) weight controller separately and available for use with.

[Mgalutia88]

I used google translator to help

[Mel46]

Whatever that quote meant:-\ when they (the Japanese) translate to English they should have someone check their translation for correct english. Otherwise it is open for misinterpretation because it makes little sense.I guess Google translator didn't help much on this one.

[dasshreddar]

Yes it is their speed booster. Start at yuminashi global to look at the products then go to links for a list of distributors.

On the rollers, I just remember seeing different weights suggested for variators depending on if there was an aftermarket exhaust or not. Here's my thoughts. The more power you are making, the quicker the variator will be thrown out so you drop weight, usually a two gram suggested difference, to slow the opening of the variator.

that site has been down, some squarespace bs

rzracing.nl has some nice yuminashi 150 stuff, but they don't ship to the US

[Mgalutia88]

Pcx racing out of France is where I got mine. On the top right side you can switch to English. It has a picture of a flag.

[Mgalutia88]

The point was that takegawa states to use lighter weights with their silent sport (performance) exhaust.

[dasshreddar]

Pcx racing out of France is where I got mine. On the top right side you can switch to English. It has a picture of a flag.

Yes, but I can't find the "yuminashi variator" anywhere on that web site??? found the Malossi one , but I don't want that one.

[Mgalutia88]

I must have bought the only one they had in stock. Email them.

[wingz]

All torque comes from the front pulley though and the bigger the front and smaller he rear the higher your ratio. More engine power makes it easier to throw out the variator weights faster. You want the speed your weights are being thrown out to stay a constant for high speed ability. Think abou centrifical force. If you have a heavy weight on the end of a string and you spin in a circle it takes little force to make the string taught. If you reduce the mass of that weight on the string you find you need to spin faster to make the string taught. It's the same theory as power in our scooters. The more power the engine makes the lighter we want the rollers to be because we want the string to become taught at the same time. If it becomes taught too soon then your top speed is decreased. Engine rpm I when the variator is changing is a constant.

How is it that the torque driver doesn't decrease the gear ratio when it is subjected to more torque (load)?
I thought that was its fundamental purpose.

[Mgalutia88]

It is however look at that as a seperate function all together.

[wingz]

I think I understand now. Very easy to get confused.
One cannot consider the torque driver separately as it works together with the variator.
The answer lies in the formula for centripetal force. F= mrw² (where m = mass, r = radius, w = angular velocity which is proportional to rpm).

Centripetal force on the rollers is proportional to (rpm)² and inversely proportional to inward force exerted on the rollers by the torque driver.

The torque driver will push the rear pulley halves together and hence the front pulley halves apart with a force proportional to engine power.
The radial force on the rollers is thus inversely proportional to power
The radius component of centripetal force is inversely proportional to power.

The gear ratio is proportional to the radial position of the rollers.
Engine rpm is inversely proportional to gear ratio (and hence the radius component of the centripetal force).
In this scenario, engine rpm is proportional to power.

Combining the bold statements, centripetal force is proportional to (roller mass) / (power) x (power)² which simplifies to (roller mass) x (power).
Therefore, an increase in power results in a proportional net increase in force pushing the front pulley halves together.
In order to maintain the original centripetal force, one needs to keep the mass of the rollers inversely proportional to power.
That is, one should use 10% lighter rollers when increasing engine power by 10%.

[sendler2112]

That is, one should use 10% lighter rollers when increasing engine power by 10%.

Probably the opposite. If the torque slot is more active with increasing power, pulling the gearing lower constantly, you would need heavier weights to keep the same rpm that you had before. But the angle of the torque slot may make a ratio out of the change in power so it might not be 1:1. You always end up changing weights by trial and error to get the target rpm. The important thing for max acceleration is to set the weights so that the engine pulls at the power peak when pinning the throttle.

[wingz]

That is, one should use 10% lighter rollers when increasing engine power by 10%.

Probably the opposite. If the torque slot is more active with increasing power, pulling the gearing lower constantly, you would need heavier weights to keep the same rpm that you had before.

That is what I said a few posts back. http://www.hondapcx.org/viewtopic.php?f ... 065#p29000
But I was wrong. Was I?
It is terribly confusing.