Sorry I haven't updated this I'm on a felt faker gas frame now with triple tree forks and disk break in the front and rim break in the back both set up just right trust me I can stop lol
I did not intend to be condescending in my first post. Safety is and should be the most important factor. Because...if you do a humpty dumpty flip act off the bike at 50 you will not have to worry about speed for a long, long time.
Ok then here is the path I took to upgrade my engine... As I stated in my earlier post, there's many ways to get a motorized bicycle to get to 50mph.
I have a single speed pedal bike. No gears...and a 10/38T sprockets on the engine side.
I copied almost everything from others forum members. I had one forum member help me a LOT with advice along the way.
The 50 mph barrier was not my intentions when I set out to upgrade. Just have a reliable engine which has the power to roll me along at speeds about 30-35 mph, not be over taching, and not need pedaling too much to start off.
I bought a long rod 40mm engine from CDH Power, a Mineralli vertical cylinder spacer/VM20 intake/reed/ and carb insulator from Smolik Performance, a VM20 clone on Ebay (there's many imposters so you have to be careful choosing), a capnip cdi(I paid $29. He is now $200 for the same thing!) an Athena cylinder kit(070100), and a Jog 50 pipe on Ebay.
Edit: forgot bearings...4 bearings rated for 13K I think..PGN
Most everything is bolt on and run except balancing the crank, fabbing a magneto key that retards the timing some, and custom fitting the Jog pipe. No stuffing, porting, or other mods.
This all cost right about $575 for it all shipped to my door. I do realize there are cheaper or faster set ups. I bought mine a piece at a time over many months so I did not have to lay out $575 all at one time.
This set up has been very reliable and performs beyond my expectations. It will get above 50 mph as I have done it quite as few times and it does not take holding the throttle pinned for a long stretch to get there. These's a good bit of power left in the tank when I let off. I lose my nerve going that fast on a bicycle. I have visions of a locked rear wheel or either tire blow out.
I started with a cheap chinese Mineralli kit and did not balance the crank with that kit to the extent it's now balanced & trued. A ring guide pin came out and scored the cylinder. I suspect the excessive vibes contributed to this failure...or it was just chinese junk.
