tell me which to use

I have these four engines to build my motor bike with, I live in north carolina where the 50cc rules do apply

49.5cc motor from a chinesse scoot (will end up either belt driven or friction drive)
3.5hp briggs and straton (is it to big? im a big guy so trust me its not to heavy)
5hp briggs and straton (this thing cant be street legal can it)
weed eater (use to be an outboard motor from a summer project 11 years ago)

what can i say im a mad scientist with a taste for off the wall

Definitely TOO HUGE for 50cc.

But the 5 hp sure would be cool!

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http://oilslubesfilters.com/ AND NOW http://www.sickbikeparts.com/

You might be able to get away with the 3.5, but you'll not want it to say 3.5hp on it anywhere

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http://www.jasonhight.net/videos/mot...etowork-sm.wmv

I'd go for the CCS engine (cheap chinese scooter). It's got a variable transmission as well, plus it's "legal".

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If it ain't broke, and you mess with it long enough, it will be.

yes and lucky fo me the rear half of the engine already faild so i dont feel so back chopping it off

Im debating weilding myself a trike together aswell

OK Ive decided, THe challenge that I being currently both broke and unemployed. I am gonna make a motorbike. and the one rule is i cannot spend any money doing it.

I have what most of you have a few bike frames, i also have a few motors and i have one thing most of you dont. an old scooter i got off craigslist.

i got it and its twin brother from a ladie for 250usd and built one from them. i still have a good motor with a ruined cvt.

Parts i will be using
chinesse scooter engine, tank, throttle, cdi, I hope i dont need the cpu becauseits dead. also the harnes is cut so i will have to rewire the engine a little. good thing is the magnetto supports a full lighting system.
huffy beachcomber cruiser (hunter green of course)

i need to install a front brake, mounting hardware, and a battery(for the electric start)
im keeping the front half of the cvt transmission and welding a sproket to the clutch nut.
and finaly i will set up a sproket on the opposit side of the tire to the peddle sprocket

Remember everyone ive never made an mb before.
Ill take all of your advice i can although the trik design with that wonderful 5hp briggs and stratton is looking like so much fun

ok the trike thing is still making me want to build it. so who wants to see me build a mt
(mototrike) i can always change engines to the 3.5 down the road (which displacement on is 115cc according to a website i read.

Build it, and post some pictures along the way.

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If it ain't broke, and you mess with it long enough, it will be.

Build The Biggest One You Can Remove Any Stickers That Say What Hp Or Cc It Is And With A Big Grease Pen Write 32cc. :d That Way If Questioned You Can Say Well Its Looks Bigger That 32 But Definatly Not Over 49.

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MEASURE ONCE AND CUT TWICE.......WAIT A MINUTE