The Razz unfortunately doesn't offer much in the performance modification department. You can however get a 70cc kit from an early model Zuma to work but you need all the intake parts from said Zuma. With a Zuma big bore kit you will need a larger carburetor and either a Zuma factory exhaust or an aftermarket exhaust. Some modification to the exhaust may be needed. The easiest thing to do to add a little more top end speed is to put slightly bigger tires on your scooter. Stock size is 2.5 x 10, you would want 3.0 x 10.
It can go upto 45km per hour depending on weight and weather, which is about 72 Km an hour.
Try replacing your current 2 stroke oil with 100 percent synthetic 2 stroke oil. Available at any motorsports dealer. Worked for my Razz. Has not smoked since.
there is a little screw on the back of the carb. if you loosen it, it will idle slower, tighten it, it will idle faster.
If gas is leaking from a Yamaha Razz muffler, then the float may not be set correctly. This means that it is not shutting the intake off.
2 places
Here's a link for the Razz repair manual-http://www.mediafire.com/?xibwfty2mtj
Yamaha Razz Service Manual (found through Google and another WikiAnswer question) http://www.mediafire.com/?xibwfty2mtj Also available at http://scootertime.net .
.039-.043
There are several reasons why a Yamaha Razz may quit running. These include issues with the engine, its age, issues with spark plugs, lack of gravity, lack of oil, lack of gas, etc.
The VIN (Vehicle Identification Number) for a Yamaha Razz, like any vehicle, is unique to each individual unit and is not a standardized number. You can find the VIN on the frame of the scooter, often located near the steering head or under the seat. If you need to obtain the VIN for a specific Yamaha Razz, you would need to check the vehicle itself or refer to the documentation provided with it.
http://www.scootertime.net/viewtopic.php?f=39&t=954
Does it run on choke? Is it starving for fuel, if so is the needle valve set for the float?