Big Bore install complete, Look at those fins stick out past the head, new size 65cc's ,thats a 33% increase, present speed 43mph that's a 30% increase
I installed the big bore kit and adjusted the carb air mix more rich ( left/counter clockwise)
I also adjusted the oil pump for maximum I am also adding a mall amount of oil to the gas ( just to be safe)
There was some lean surging when cold untill I move the throttle needle to the bottom notch and adjusted the carb again ( I have re-jeted the carb to a #81 jet since then)
the NC/NA 50's with wind up starter (77 - 80 ) , DO NOT have an adjustable oil pump it will be nesscessary to use premix fuel if you go big bore mix at 24:1
70cc kit by mfg by DR Racing and Purchased from www.50cc.nl , contains, new aluminum piston , new 46mm bore cylinder, gasket kit
I'm using a 1977 express carb & intake and mounted a 2pc Biturbo exhaust designed for the Tomos moped ( a cut & weld mod is nesscessary to attach the biturbo to the express exhuast pipe ) ,the biturbo came Themopedwarehouse
the head HAS to have the chamber opened up so it is the same diameter as the new bore try to mantain the same contour , and a new drive belt has been fitted, the variator has had two of the rollars/weights removed.
A bolt on ( NO welding ) Proma performace style exhaust is available from VT cycles in Hawaii for $55 plus shipping. He informs me these are of limited supply.