Motorcycle Repair: Speedfight 2 help, speedfight 2, shively

Question
Hi
I have a speedfight 2 50cc and it is de-restricted but the exhaust is stock, it
does about 50mpg when it is staed to do 120mpg I do usual riding, the top speed
has laso dropped from 55 to 50mph and the acceleartion is poorer than it used to
be and also when cold and started up it bogs down. I have cleaned the air filter
and replaced the spark plug with a new one and the colour of the old one was tan
so no rich or lean fuel. Please can you help

Answer
Hi Roger,

The derestriction process likely left the engine de-tuned.

Decarbonize the exhaust.

The carburetors probably needs to be tuned to correct air-fuel mixtures even though they last appeared the proper colours.

Consider a performance pipe.

Respectfully,
Mark Shively