Tuning Your 50cc 4 Stroke GY6, QMB139

[streido]

so it holds the CVT in a lower gear longer

No, its the roller weights and rear spring that controls that really. The guides that hold the rollers are different im sure on the race variators which changes how the rollers move up  and down.

It just feels much smoother accelerating and gained me an easy 2-4mph top speed. I used to get a flat spot on acceleration between 25-28mph when i de-restricted, after i fitted the race variator it went away and it just felt so much nicer to ride.

[wordslinger]

..be careful to watch the I.D. on those cheaper variators...

..the bushings are often made of soft materials, and can wear pretty quick...

..symptoms might be vibrations and excessive harmonics .........

[OregonDad]

Looking at several variators and seeing different angles of attack and length of travel.  I think I will just stick with the stock Kymco.

Our goal is a bit different than others since my son only has a restricted moped only license and should not be going over 30mph anyway.  Anywhere he can legally go has a top speed limit of 40mph, so I do not want the scooter to be able to go over 40mph with an 180 pound rider.  Take off and acceleration are currently fine, but the small 49cc sucks big time on hills even with the cdi notched.

Looking at replacing stock cvt parts with smooth boss, 5.5g rollers, 1000rpm clutch springs and a 1500rpm contra spring.  Then when I get ambitious enough to tear off the seat, up jet to 82 and replace the stock spark plug with NGK.

[zombie]

Looking at replacing stock cvt parts with smooth boss, 5.5g rollers, 1000rpm clutch springs and a 1500rpm contra spring.  Then when I get ambitious enough to tear off the seat, up jet to 82 and replace the stock spark plug with NGK.

That's the correct recipe.

[OregonDad]

Now we just have to see if I can cook.  Removing the carburetor makes me nervous.

[streido]

Now we just have to see if I can cook.  Removing the carburetor makes me nervous.

Chicken! 

I was the same 1st time but it is easy. Honest.

[KymcoManc]

Chicken! 

I was the same 1st time but it is easy. Honest.

Me too, but after that 1st time you realise its a walk in the park & after the 5th or 6th time you feel like its all you've ever done lol.

I posted a youtube link somewhere on my 'im desperate thread' after removing, it got me started in stripping the carb down cleaning jets & all.
The jets are a doddle, really!

[zombie]

And yet another tuner is born.

[KymcoManc]

And yet another tuner is born.

Maybe your right as my fuel consumption has increased since, its running smoother & quieter than ever & is starting on the button 1st time :-)