Hello i have 88r with porting billet head installed cyl spacer and older piston hasno low end .have lectron 40mm carb dyno port pipe .ithink the port timing is off any ideas .the unit is used for top speed runs only so far 91moh tied low no fenders good tail wind .thanks

 

With what you've done to the motor it won't have any bottom-end. Like you said, high-speed runs only and that's what you have.

 

i have an 88 r with about the same mods and i havent had a problem yet with lack of bottom end.mine has a yz250 piston thought but im not sure what year the piston is from if uwant me to find out i can so maybe you could try that