how to get a higher top speed

Hi, I have a Vespa 50 (1964) and I’m trying to tune it up with all the money I have. I have already got a racing barrel, piston and crank. I am just wondering if anyone knows the best way to get to higher top speed, yet keeping the engine as a 50. Many thanks for replies, jordan

hi,

 

mount these two parts -  and you start to  "fly"

 

http://www.sip-scootershop.com/Products/20020300/Rennauspuff+POLINI+V50.aspx

 

http://www.sip-scootershop.com/Products/97200000/Primarzahnrad+PINASCO.aspx

 

 

regards