I need a lot of help

Okay so I'm attempting to mount a free Poulan 33cc chainsaw on a mini bike frame i got for $30. The rear sprocket on the bike is 72 so i figured if I bought a chain and 12t sprocket for the saw it would be a good ratio (6:1)..I'd rather not use a jackshaft because of the extra money and work to mount it, (but this might be the only solution because if i cannot move the sprocket to the other side of the wheel the bike will run backwards), is it possible to just make it like a bike and use one chain?
Also, can I take the chain-sprocket on the saw (for the cutting chain) off and mount a sprocket on it? or is this stuck on there? I have seen others do it before so it must be possible.
How can i get the most speed and torque out of this bike? I think the wheels are around 6-10 inches in diameter and I'm new to gearing and ratios.
Any advice is helpful, if you need more info to help just ask.
Thanks,
Isaac

 

[butre]

6:1 is incredibly low. You want something more like 14:1 for a small engine without gears.

 

[engineer kid]

So If I wanted to keep the rear sprocket and not buy a new one would I have to use around a 5 tooth sprocket? I'm very new to jackshafts so how would I gear one of those if I had to?

 

[engineer kid]

so i did some looking and if i buy a jackshaft with a 10 tooth on the engine, to a 20 tooth on the jackshaft, then another 10 on the jackshaft to a 72 on the axle which gives me a gear ratio of about 14, would this work?

 

[keatonx]

6:1 sounds fine for a typical minibike sized tire, what's the diameter?