Engine Trouble Help with bike build

[treys2k]

Hello, im new here so let me knoe if this is the right place to post. So I have a 25cc weed wacker engine Im putting on a 20in bmx bike. Instead of friction drive I actually attached a sprocket to the drive shaft. The motor is bolted into the frame. The pull start from the motor was damaged and removed. My question is if I run a chain right to the back wheel off the drive shaft mounted sproket with no pull start how could I start the bike?? Thanks for any help!

 

[crassius]

without a clutch to disengage the motor, I'd think the question would become "how to stop the bike?"

 

[KCvale]

I have a 25cc weed wacker engine Im putting on a 20in bmx bike.
Instead of friction drive I actually attached a sprocket to the drive shaft.
The motor is bolted into the frame.
The pull start from the motor was damaged and removed.

My question is if I run a chain right to the back wheel off the drive shaft mounted sproket with no pull start how could I start the bike??

If it has no clutch so just pedal it, it will start, but die every time you come to a stop.
If it has a centrifugal clutch you can stop with the engine running, but you can't start it by pedal bump starting.

This is why all MB 2-stroke engines have a manual clutch.
You pedal them up to start, and hold the clutch in when stopped so the engine don't die.

You can get a new pull start but it's a 25cc engine meant for high RPM and minimal load (it just spins string), far from ideal to power you on bicycle even if it was free.