in the cover where the kickstart is there is a thing called a variator its on the left as you take off the cover,undo the nut on the end of the crank that holds it on and take out the wedding ring shaped washer and put it back togther it will do about 50mph then.also there may be a red/white witr on the cdi unti try disconnecting it it may stop the rev limiter cutting in.
adam bike doctor
February 2009