Gearing for the gy6 150

[ckau]

There has always been questions posted about wanting more speed or torque. Some wanting speed while others wanting the pulling power. The axle sprockets is the most obvious to change out but the selection is small, maybe 2 or 3 choices to choose from? You either have to go one way or the other.
Take a closer look at the internal transmission gear sets! You have all seen them advertised on the scooter sites but maybe you never really considers how much of a impact the right number combination can do for you.
In example: the Howetts, there is a 13/40 combo that pulls like a horse but hard to get above 30 mph without some serious motor mods. Our carter had a real good top end, [38 mph} with a 14/36 set but couldn't stretch a wet noodle! This is just a example of two extremes.
The main difference between these two buggys, even though they had tires and external gears that were approximately the same, were those internal transmission gear sets!
We could go crazy with all the math but to keep it simple: A 13/40 set is real strong on torque! The smaller the front number and larger the rear number equals more pull. Vice versa - larger front, smaller rear number equals speed.
If I had a 13/40 set... was happy with the torque but wanted a little more speed without loosing much pull, I would go to a 14/39 set. The 13/40 has a ratio of 3.07 while the 14/38 has a a ratio of 2.78 The higher the ratio equals more torque, smaller ratio number equals more speed. I would probably pick up approx 5 mph without much noticeably torque loss.
Unfortunately, the only sure way I know of to see what you have is to pull the clutch, remove the trans cover plate and count teeth. If anyone knows a better way please post! For me, It means loosing gear oil and a cover plate gasket just to find out!! but if you are serious, take a look! It would be good to post a make, model and count to help all of us know what buggys got what and maybe consider this option.

[GX150]

Exactly! I just posted on gear sets.

My Yerf was a rock crawler running 12g sliders, 2000 RPM torque spring, A12 torque cam, 13/40 gear set and 13/39 sprockets. Even with UNI and performance CDI and coil, it barely ran faster than 30 mph. Because of the gearing, the CVT belt did not have to be replaced for over six years due to aging and it still had over 2/3 of the original clutch pads. This little 150cc had no problems running in loose sand or hitting small dunes at 20-25 mph because of its setup.

[ckau]

Originally Posted by GX150

Exactly! I just posted on gear sets.

My Yerf was a rock crawler running 12g sliders, 2000 RPM torque spring, A12 torque cam, 13/40 gear set and 13/39 sprockets. Even with UNI and performance CDI and coil, it barely ran faster than 30 mph. Because of the gearing, the CVT belt did not have to be replaced for over six years due to aging and it still had over 2/3 of the original clutch pads. This little 150cc had no problems running in loose sand or hitting small dunes at 20-25 mph because of its setup.

You make a very good point, Pete! The higher ratios (torque) take a lot of strain off the belt, clutch and chain.There's some that can't keep belts or clutches from overheating and failing. It may be that they are simply not geared correctly for their riding style.

[Hurricane]

I know I am congering up a old POST BUT
I need to go slower and have more torgue;;
See I have built a Paintball "TANK" and by rule cant go faster than a "walking" speed
But have loaded down the buggy with every thing from a plywood & steel body to guns & air system. At home (flat land) we have no problem, but on the road in the hills I cant make it to the top.
I have a Fuxin 150cc M# GK150 two seater
Qusetions
Is this a copy GY6
do I change "drive" sliders & springs OR gears

Hurricane
"Slow Movin Destruction"
Bayou Mafia