Should you feel the automatic transmission in a 150cc scooter shift?
Friday, September 10th, 2010 at
5:00 pm
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a friend of mine recently bought a 150cc scooter, we were both on it and it was going well above 30… more like 50-55mph….we even had 3 people on it and it still hit 45…
and no, it never shifted…
Did you buy it new or used? It sounds to me like it is a used scooter.
If it is a 150cc engine then it should go quite a bit faster. I say this because I fear you may have been lied to if you bought used.
If it is a new 150, no, you should not feel any shifts as it has no "gears" as such. The transmission gearing is determined by a V-belt and two variable diameter pulleys.
As your speed goes up, the working diameters shift from small in front / larger in rear to more nearly equal working diameters.
Some designs like the Comet 40 series (an aftermarket CVT brand) actually can shift to an overdrive ratio, if you have the horsepower to pull the overall ratio.
Get the scooter to a good scooter mechanic or a dealer that sells the brand and have it fixed. It may be a worn belt or something damaged by abuse.
Budd
There are no gears in a CVT transmission for gas scooters. The CVT stands for continuously variable transmission. Basically there are two conical plates that the belt rides up and down as the plates spread or get closer. When the conical plates are closer together, the belt rides higher (higher gear), when the plates are further apart, the belt rides lower. So you will not feel a shift in gear. As far as the 30MPH top speed, I know that a lot of scooters will max the speed out around 30MPH if it senses that the kick stand is still down. This could mean that you have a bad or stuck sensor.
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If it was used there is a possibility that there are a couple of problems in the CVT. 1. the rear pulley has gotten locked into place and doesn’t move to shift, or 2. The rollers in the front pulley have gotten flat spotted. 3. Worn belt…
Truthfully if it is a used scooter I would say buy another rear pulley assembly and a new set of rollers for the front pulley, along with a new belt preferably kevelar belt… The CVT isn’t that hard to work with, it just takes an air wrench and taking some time to keep the parts clean. Also get you some graphite and slightly lube the new rollers with it by applying it to the each roller in your fingers, then you can do the sleeve or boss the same way, also applying some to the brass bushing inside the front pulley…
The rear assembly is a little tricky to disassemble, and really the only parts sold for it is the clutch and the tension spring that shifts the rear pulley. What tends to wear the most in the rear pulley is the pulley half slides back and forth to shift. The rear pulley half is put together with sliders, it has 3 grooves machined out in the wall of the pulley housing. Those 3 grooves are kept in place by pins, it slides inward and outwards via these 3 pins. Under acceleration the pulley grooves put much tension on the 3 pins and they start to wear an ever so slight notch out in the grooves. Thus when you try to take off or get to a shifting point, the rear pulley starts getting locked into one position in your gear range. It is like trying to ride a 10 speed with the shifter cable broken.
There is no way to fix this problem with the rear pulley. If you machined the grooves, you would have to have bigger pins, and also the pins bend slightly under torque also so there would be the second problem…
Here is a link that will help, the basics are the same, your rollers maylook differant though. If you have any other questions email me, I have worked on many of scooters. http://www.flexistentialist.org/blog/archives/2003/10/27/cvt-basics-constant-variable-transmissions