need speed

Can anyone reccomend an idea to get a little more speed out of my elcheapo 80cc? It goes about 30mph as is. Would like to hit 40 at least. Also best site for replacement parts? Thanks.

 

[butre]

porting is the only way to get an extra 10 mph out of it

 

[The_Aleman]

If you're really intent on getting more speed out of your chinagirl, the single best way to go about it is to put on a smaller rear sprocket.

Using a standard kit 44T as an example, the chinagirl will be @ 6K RPM @ 26MPH with a 26" rear wheel. 30MPH is 7K RPM.
Every 1T smaller you go on the rear sprocket will get you about 1 more MPH at same RPM.

Therefore, if you used, say, a 36T sprocket, you'd get 34MPH @ 6K, 38MPH @ 7K.

 

[KCvale]

If you're really intent on getting more speed out of your chinagirl, the single best way to go about it is to put on a smaller rear sprocket.

Gearing of course, gears change everything, but you still need the engine beef to push it.

Once you hit ~32mph wind resistance is like ~80% of the battle to gain more speed.
You need engine beef to overpower wind resistance if you want to sit up, or get aerodynamic with cowlings and low tucked in riding posture if you want to go really fast, but please just keep in mind you need to improve your brakes as you improve your top speed.

 

[The_Aleman]

I had no problem hitting 38-42MPH with a stock 66CC and a 34T rear sprocket 8 years ago. I'm 6'4" 230 and ride bagged bikes.

Of course, the only reason I changed my sprocket was so I could cruise at 30MPH without spinning my engine over 6K.

Chinagirls make pretty good torque between 3-5K RPM, even with a stock pipe.