Feeling a bit down...
The bike is a Puch Magnum MKII. Ran stock at 30mph.
Added a 70cc euro-kit (Amal carb.) Once all the parts were on and made to work, it tops out at 37-40 mph. The bike pulled strong to that speed and just leveled off. The engine is turning some pretty high rpms at this speed. It's a 2-speed and it is shifting properly.
Pulled the 70cc kit because it was loud and vibrated like hell.
Went back to a stock 50cc head, 15mm BING carb with a 14mm Puch intake bored to 15mm. Added some holes to the baffle of the stock exhaust...probably doubled + the flow. Added a low restriction air cleaner. Rejetted the carb from a 60 to a 64. Runs nice, but only hits 35 to 37.
Added the Bi-turbo to the mix...no improvement, just louder.
Is this all there is? The timing seems good..plug looks good... I thought I should see around 45mph at 70cc and 40mph with 50cc.
I've heard these 2-speed Puchs don't produce much speed. Any truth in that?