Clutch main spring. By curiousgeorge (Read 1,875 times)

[curiousgeorge]

I am looking to upgrade my clutch main spring on my 50cc scooter and wanted to know if anyone can recommend a good clutch mainspring to upgrade too that will give me better acceleration but not affect my top speed. Also does anyone know what would be an optimal roller weight set up for a 50cc scooter as well?

[Bashan]

Steven at MonsterGY6 sells very nice mainsprings for 50cc and 150cc. I'm not sure if any of our banner folks sell for 50cc or not. The blue is 1,000 RPM, the yellow 1,500, and the red 2,000. The red spring is the stiffest. Most stock GY6 springs are around a 1,000 or a little less:

Click image for link

I'd go with the yellow, if you do the red you'll need more HP to push the CVT all the way to it's highest ratio IMO.

The RPM designation is erroneous, the mainspring doesn't control the clutch engagement speed. It simply puts pressure on the pulley to slow it's advancement as the RPMs increase. So a stiffer spring keeps you in lower ratios longer which makes for quicker take offs. It's the tensioner springs that control the RPM at which the clutch pads engage.

[curiousgeorge]

Then what would you suggest for tensioner springs and on top of that can you me to the specialty tools i will need to take the whole assembly off the cvt and then get to the spring as well?

[curiousgeorge]

Are there good tensioner springs you would recommend for optimal performance with that yellow main spring in my 50cc scoot?

[Alleyoop]

With a stiffer Contra spring you will need more RPMS to get to top end speed. Reason is because the Variator now has to work harder to pull the Clutch Pulleys apart to allow the belt to move down for top end speed.

If you want jack rabbits starts and high rpms to reach top end speed then go for it. Here is the thing I always recommend that when you get on your scoot and your give it a little throttle it should start to move anywhere from 2000-3000 rpms the most. So if someone wants to put in springs either Clutch Springs and or Contra Spring I always recommend the 1000. The OEM springs that are in there are usually rated at 700-800.

For example if your current current STOCK it starts to move say at around 2300 rpms and you put in 1000 rated springs add that 1000 to your current 2300 it takes to initially move the scoot. So now your rpms have to reach 3300 before you scoot starts to move.

Now the contra spring it puts a lot more pressure on the belt and heats it up. And if you have a cheap belt on it, it will start to tear and usually will either break or shred into tiny pieces and it usually happens when your flying down the road at high speeds.

Just so you know what some of these things can do and not do. Some are good some not so good. But Like I said if you want JACKRABBIT starts and high rpms that is what you will find changing to stronger springs.

See my trike there It is build up to 182ccs from 149.6 it is a heavy trike 350lbs plus my weight which is 180 lbs but It starts to move at right around 2300-2500 rpms.


So I recommend first get all that stuff off if your going to do it then work on your weights and then if NEED be a stronger spring.
Alleyoop

[curiousgeorge]

Great advice allyoop! I will definitely go find the right tools so i can easily remove the variator to get to my roller weights. Also I wanted to replace my belt anyways so i have a more reliable one but wanted to know, how do i check the size of my belt so i know what size to order my new one. Another thing. Since I am getting a new UNI air filter and at the same time Upjetting do you think that will give me enough horse power for the stronger springs if i do end up needing them as you put it? P.s. This is off topic, but I saw people upgrade their exhaust sometimes and wanted to know what are the benefits and cons of doing this?

[Alleyoop]

The belt size is printed on the belt so once you take the CVT cover off you will see the size of the belt. The belt is probably 669-18-30 belt that is what most 139QMB motors use.

On a 4 stroke changing putting on a Free Flow Filter and Exhaust and re-jet just gives you a tad more power, nothing outstanding.
A performance exhaust what it does give you is more noise(HAHA), and makes you think it is really cranking out. You may notice a little difference but it is not a heck of a lot.
So the bang for your bucks will really come from tuneing the CVT the other stuff not so much.
Alleyoop

[curiousgeorge]

So first things first, get a tach and then some rollers to start tuning it. Then if i want fast acceleration i can get a slightly stronger main spring too? What do performance clutch's and performance variators do?

[Alleyoop]

Yes, you got it get that tach that will help you a lot in tuneing the motor(adjusting the carb for good Fuel Ratio Mixture) and the CVT.

Well the spring all it is going to do is REQUIRE more rpms to get up to speed, the motor will not produce any more power. All it will do is just like a car with a Clutch at the drag strips, you put in the clutch and rev the motor up to certain RPMS then pop the clutch and your off.
BUT like I said because a lot more pressure is put on squeezing the belt it will wear faster and it creates a lot more heat. It will not give you any more top end or give the motor more power.

Performance Clutch(s) some are a little lighter and some have more PAD MATERIAL on the Clutch arms to grab the BELL better so less SLIPPING accuors.

Performance Variators have to be larger in Diameter than what you have otherwise forget it. You want a Performance Variator that is larger in Diameter than what is on there so the belt can climb higher for more top end. You also have to check the size and see if the Larger Variator WILL FIT and not hit the case.
Alleyoop

[curiousgeorge]

Thanks for all the info alleyoop!