Skip navigation

Here is some VERY useful CVT transmission tuning info for the Elites and other cvt based scooters, posted by member “Arnadanoob” from, much thanks bradah!

Also a vid of a kymco variator vs a stock one from an Elite S, very similar to an OKO performance variator showing you the difference between them


Tech info:

The variator rollers (weights) are the key to tuning in this manner during the initial take off. If you use less weight in the rollers, it’s more than likely that you’re using a softer center spring. If you did make the mistake of using lighter weights with too strong a center spring, you’ll have a whiny engine revving up really high, great for steep hills that won’t have any top end speed. Conversely if you made the mistake of using too much weight at the front pulley and too soft a spring, you’ll lug, bog, and have very dull power and your pipe will never see the airflow it needs to fill up, pressurizing the pipe’s internals to create the necessary backpressure to keep more of the fresh intake charge from blowing out the exhaust port. A lower rev pipe fills up quickly which means it doesn’t need higher rpms to put the bike into the power zone, like a V8 Typhoon pipe, this is why you can get away with heavier weights. PG Long is a very high rev pipe, needs a lot of airflow before the pipe pressurizes before backpressure can be formed to hold more of the intake charge in the cylinder before being blown out, this is why it needs less weights to help keep the crank rpms higher.

Tuning the rear section (rear pulley and center spring) determines rate of acceleration (thus how hard you pull while you increase speed in mph/kph) and also the rate in which it gets back into the power zone when you punch it from 1/8 throttle to 1/2 or 3/4 throttle, even WOT. If you think about this in car terms, the idea is that when you accelerate, you’re always in the meat of the power zone, but when you’re cruising you might be below it at lower rpms, but as soon as you punch it, it should kick you back into the power zone instantly without delay and pull hard (only limited to your gearing ratio).

There’s a lot of mathematics behind tuning bikes correctly, even in Hawaii we have a ton of guys running super lightweight trans setups with any combination of (lathe lightened Keli pullies), aluminum driveface, lightened mag, super light clutch and lightweight clutch bell without understanding the effects and applications of each. If you intend on riding long distances at a steady speed, there’s absolutely no reason to use any lightweight trans parts as it’ll actually hurt you in the long run.

For example, when a bike is in motion, it undergoes changes to its level of kinetic and potential energy. Lightweight moving trans components will not be able to store as much energy while it is spinning and will want to slow down at the earliest possible convenience. This means if you went with lightweight everything versus someone who’s using stock driveface, unlightened Keli pulley, stock clutch bell, heavy/stock clutch, your engine will be working harder to maintain that high speed. Parts with larger mass will be able to store energy better, which means like a bowling ball that starts to roll down the street, won’t be looking to slow down nearly as easily as a volleyball when it starts to encounter resistance. The bowling ball’s real problem is getting up to speed. In mopeds, the lighter components often help for the shorter rides which involves more sharp acceleration from 1 corner to the next where your rpms vary a lot, it does not help those who hold it wide open for miles and miles, in fact it will hurt your mileage and will wear out your motor faster than without those lightweight parts. The total mass (weight in crude terms) of the moving trans parts is perhaps the most overlooked, underestimated, often misunderstood portion of the bike. A bike setup that almost mandates the need for lightweight trans parts are those who are using chamber pipes, mostly due to its powerful “spikey” power curve which often results in a huge kick when the pipe’s powerband is reached.

This skews off a little but I wanted to add in why clutch springs (not to be confused for the center spring) acts differently in heavy, medium and light clutches. A heavy clutch has moving parts that are higher in mass, which means when it spins it’s going to want to open up and touch the clutch bell surface more eagerly than a clutch using ultra light moving parts. This means you could use a green polini clutch spring in a heavy and light clutch and it’ll seem like the clutch is engaging sooner with the heavy clutch than the light clutch.



Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: