friction drive need help!! can't figure out drive shaft or sleeve

[abombs1227]

I have a weed eater engine that I"m trying to mount as a friction drive.My problem is that I
can't figure out how to either put a shaft on the motor or extend the one that is factory. I've heard
about how ppl use bmx pegs but they are too big in diameter to fit thru. the plastic engine cover and are a larger thread than the drive
shaft.
I'm assuming that the bolt thing on the threaded drive shaft is a sleeve bcuz this motor has no clutch.
The sleeve is only a few inches long which as you can see in the picture doesn't extend out past
the plastic engine cover.Do most weed whackers have a longer drive shaft than mine??
Any ideas on what I can do to solve this???Anyone have this problem before??
The sleeve/drive shaft in the picture threads on a bolt coming out of the flywheel.At the top of this sleeve there is a square opening which the cable goes into that actually turns the shaft of the weed eater.It doesn't have threads so I can't screw anything into the end of it or around it for that matter.
Do I need to have something special machined?Or is this motor just not usable for something like this?
I thought about welding something to the end of the sleeve but there's no way I could get in perfecting in alignment while spinning which I think would throw everything off in the motor and cause it to wobble too much.
Any help would be greatly appreciated.