How can I adjust parmakit on my vespa 90ss

hello

I have 1965 vespa 90

I put malossi 136 cc , 25 malossi carb and parmakit.

I build the motor it works but timing is not correct.

at low rpms bike is like a bicycle and than when it comes to middle rpms it comes high rpms easily.

help me to adjust it to correct timing

HI;

SET THE TIMMING BY 2500 RPM TO ABOUT 20 DEGREES- IT SHOULD REGULATE DOWN THAN TO 13-12 DEGREES IN HIGHER RPMs

 

THIS KEEPS YOUR CYLINDER COLD

 

USE EVER A STROBO LAMP TO ADJUST!!!!

 

which exhaust do you use??

 

 

REGARDS