Tuning your CVT, about rollers, springs and the like

Posts: 200

Being on here for a while now I see a lot of questions and general misunderstanding about about rollers, springs and the like.

Keep in mind that all of these engines an therefore the CVT's and clutches on these buggies are adopted from scooters. So a here are few words on the subject from a guy right out of 'scooter land' Europe.

About springs and colours
The color system on springs is dependent on what make the springs are, and which engine(i.e. clutch) they were designed for. Almost all springs I see being sold in the US are made by Malossi. They use the white, yellow, red, black system. For each engine/clutch combo (i.e. scooter type) its own range.

So the red springs for one engine is totally different than the red springs for another. Same goes for main springs. You just have to cross reference your engine type to the scooter that uses the exact same engine.

And Polini's main spring are all blue, by serial number only.
So without knowing the engine...

About RPM (and statements about it)
Don't be fooled by statements about rpm ratings, there's no such thing. Both Polini and Malossi for example don't say anything about RPM. They just offer a set of different stiffness for each scooter (engine) type. It's up to you to figure out what your engine needs. It's all dependent on the combo of parts in your CVT. More on that below. Keep in mind that buggies are at least 3 times as heavy as scooters.

How to tell what you need?
If you want a strong setup, the aim on scooter type engines is to get the rpm in the power band (likely to be 3 to 8K rpm) as quickly as possible and keep it there for as long as you can. Both in throttling up and down. Let your CVT do the work!

In other words:
Get it to wind up fast (3 to 4K on most engines), get the clutch to engage close to this rpm. If it engages to soon that means you need stiffer clutch springs. It's as simple as that.

Then with the right roller weights get your front pully closing while the rpm steadily increases to the top of your power band (not by giving it more throttle!!!). If there's a hesitation or drop in rpm your rollers are likely to be to heavy. Go lighter.

The main spring does about the same job but in a reverse manor (when you go off throttle). If the rpm drops below your power band (b.e. out of corners) you need a stiffer main spring.

So you see, the rollers and main spring are inseparable.
The 2 always work in combination. Changing one will always affect the other.

I hope this will help you choose the right parts, not by going for statements or what someone else has working good for them, but by actually knowing what will be good for you! It's all not rocket science, you just have to listen carefully to what your engine tells you.

Jackster

Posts: 137

Good inputs Jackster. I printed-out your message to save it. I have a file of buggy info that I refer to. My son and I both have a Reaction 150 and enjoy squeezing out all the power we can. I have recently installed a red (labeled 2000 rpm) torque spring and yellow (no marking) clutch springs, based on information I got from Eric at McDough power sports. He told me this combo works on his wife's 150. Works for the type of driving that I do here in Arizona desert (rocky steep hills, sandy hills and flat desert). I agree that the best way to determine what you need is by experimention. The CVT is not the easiest thing to take apart so it is nice that we have this forum to get advice on what worked for others. You are right that we all have different driving habits and terrain and what works for one may not work for another. Anyway, thanks for your comments.