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Old 10-12-2016, 10:28 PM
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Agreen Agreen is offline
Motorized Bicycle Elite Member
Join Date: Feb 2013
Location: Goose Creek, SC
Posts: 627
Default Re: how much weight can a 49cc take before blowing the shaft off?

Don't poop on the bolens, it's not their fault you put 1000x the stress on the crankshaft that it was designed for! If you want to do a friction drive, do it right and copy the Staton kit model. It has bearings on both sides of the roller, so stress on the crankshaft is non-existent. Well, the excessive radial stress, that is.

Anyway, you may get lucky finding a 4 stroke weedeater, but your best bet for a non-kit (or did you really mean that you just don't want kids?) engine is probably a chain saw. I used a Poulan 42cc once. The engine was good, but the drive system had some bugs, but it worked well in the end. Maybe a Husqvarna chain saw or a Stihl would work. They're pretty decent quality, but you'll pay more for the brand. Really, it boils down to getting a large enough engine. In all reality, you probably won't find a weedeater engine big enough for your needs.

Take a look at this one:

I pretty much copied the idea of supporting the roller with a bearing on each side from the Staton kit, but I used a couple of kid's bike sprockets to drive the roller with a chain. I had to tack weld one on the back of the chain saw clutch. Everything was either found in a dumpster or bought at lowes. The metal bracket that holds the roller was found in the lumber section. I drilled the holes out to accept 1-1/8" flanged bearings, and used a piece of thread rod as the axle. The roller is a bike peg with a fender washer welded on one side. It gave me a couple issues like the rack twisting and the carb not wanting to work, but I resolved them and had fun with it!
Never stop wrenching

Last edited by Agreen; 10-12-2016 at 10:39 PM.
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