I have a Manco Streaker I have been tinkering with for the last few months. Originally it had a Tecumseh 3.5 HP motor on it. I recently put a Tecumseh (H60) 6HP motor on it. Motor runs really good. Motor also has a header on it. I recently changed oil and changed spark plug. I clocked it at 33mph with my GPS. I think its more like 35-40mph. This thing is very fast and not for a beginner. Mini bike itself is in good shape. Seat is torn in the back but still useable. Scrub brake works well. Only thing is Throttle cable broke and I have not had a chance to fix it yet. Also I forgot to mention that the handle bars were heated up and bent forward (by the previous owner) to accomodate a taller rider. I am 6'1'' and I fit on it comfortably. Asking $150 firm ($75 for the motor + $75 for the rolling frame).
Pics are from when it had the 3.5 HP motor on it. Looks exactly the same but with different motor.
Located in Hatboro,Pa
Would make a good pit bike @ the track