Chainsaw power?

[rocksalt27]

So I finally finished putting together my chainsaw build-and it doesn't seem to have any power from a stop. It's a chain drive with a large bicycle sprocket, about 40 teeth. The wheel does turn without my weight on it, but when I sit on it, it has a real hard time taking off. It's a 42cc engine, so is it a lack of torque, or is that just the way it is? BTW, what is the torque on a china girl? How bout a chainsaw?

 

[msrfan]

Do you have a jack shaft? What is your overall drive ratio? Any photos? Chainsaws are made to cut at full throttle, so that's where the main power is. You may have to gear it way down to pull your bike. There's no reason you can't get it to work for you with some mods. I highly recommend some extra flywheel weight. When I raced desert I would buy motocrossers for their suspension and add flywheel weights to tame the power band to something usable for enduro competition.
You may find the specs for your saw on line and see what the power to rpm curves are. There's some good friction drive chainsaw bikes on the forum, so that means low drive ratios.

 

[mogollonmonster]

Where did you source your primary sprocket? The one on the saw? I've been brewing up a chainsaw bike myself, and sprockets are my issue. I plan to usr either a 660 or 880 STHILL MS Magnum, the two most powerful saws in the world. Ought to be interesting...

 

[curtisfox]

Yep sounds like it geared to high,need a jack shaft to lower the ratio.............Curt

 

[mat_man]

Yep sounds like it geared to high,need a jack shaft to lower the ratio.............Curt

Yep, or go with a 10" diameter wheel.