I hate to rain on your parade and people here generally avoid being nay sayers, but there's a good reason "no one has ever done this kind of set-up". It's because it just won't work. There's plenty of good reasons car alternators aren't ever used in bicycle setups. They're super inefficient and you can't possibly spin it fast enough with small gas engines to do anything. You're defeating the purpose at every step you take. But on forums like this, every single day, someone comes up with a brainstorm of "hey, what about a car alternator"!! "Hey, I can charge the batteries while I drive"!!! "Hey, I can put magnets on my bike rims and generate electricity while I drive!!" You cannot possibly charge batteries that power an electric motor that powers the bike while the bike is running under that power. If you add a heavy gas engine to charge those batteries, you just added a ton of weight to rob you of any efficiency that you might have gotten in the first place. You seem to be thinking you're coming up with a new invention no one ever thought of. You're not by a long shot. And you can't silence a weedeater motor. They are the loudest of all gas engines. If you DID manage to silence one or another small gas engine, it would mean you blocked most of the air coming out of the exhaust and you'd lose most of your power if it would even run at all. You obviously have money to burn to find out eventually what I say is true, but you'd be much better off to just use a traditional electric bike motor and traditional batteries and be done with it and accept that your range will suck because of what we have available to us. There are plenty of choices of bike motors available to you. There are few choices on batteries. All this stuff about a heavy gas engine turning a car alternator on a bicycle is hogwash and you'll find this out in the end. But on the positive side, you'll have another contraption we can add to the Rube Goldberg archives. And I have no idea what you meant when you topped it all off with the "Austrellia" comment. What does this have to do with motorized bikes in Australia?What is unique to me, is that as far as I know, no one has done this kind of set-up.
If it wasn't for the NY law making 250 watts legal- I would not have attempted it.
If the thing works out, it could be repeated in places like Austrellia (spell?).
That quote alone is worth it's weight in gold. Regardless of what is thought of the project itself - I have massive respect for those that'll break out the tools and try! Who knows? He just might surprise us all!professor said:Update- After many hours adapting the weed wacker to drive the alternator- the wacker has not enough torque to run the alt. I could not even start the thing with the belt connected.