Anyone tempted to use cheap motorbike engines?

[5-7HEAVEN]

Hi. i know that many of the motorbike/pocketbike/moped engines are illegal because of their large displacements, but has anyone considered using these engines on their bikes? one 90cc engine sells new/complete for $79.95 on ebay, others going for about $250 with transmissions. it would seem practical enough to fab a mount into the bike's frame and run jackshaft and sprocket to the rear wheel. would their larger sprocket be compatible with what's available for motorized bicycles, as far as chains and sprockets are concerned? i would LOVE to run a 5-6hp bike engine with 4 speed auto on a fortified/modified bicycle frame and balloon tires.
your thoughts, please.

Myron

 

[custom_tecumseh]

I was thinking the same thing lately, search for Lifan engines on ebay, you'll find what I'm talking about, although they are a bit large.
Link to my thread: http://www.motoredbikes.com/showthread.php?t=6232

Those $80 49cc 2 strokes on there for pocketbikes look just the right size, and some come with a CVT.

 

[5-7HEAVEN]

yeah, the LIFAN engine/trans is one i'm seriously looking at. maybe i'd just have to buy the engine, then have the bike frame built around it.
i'm searching the archives looking for super-strong and wide wheels and tires to use, front and rear.

 

[custom_tecumseh]

Yeah I was thinking a custom frame would be the only way to go.

but then I bought this http://www.motoredbikes.com/showthread.php?t=6276

I just can't afford the time or money right now to try to do another bicycle, so I figured this would be the next best thing. I really don't want to get away from bicycles though, I'm torn between, lol.

 

[andyinchville1]

Yes....Illegal or not...It'd be really neat to have a bike go 55 MPH or so....I'd even pretend to pedal just to freak people out!.....Go for it!....I have thought the same things too....Actually I have an old YZ 250 dirt bike in the back yard less the engine ( I bought everything minus the engine for $100) That I was going to try to install a pedal system onto and then put a 50 CC dax on it....I think pedaling a YZ 250 would freak out a lot of people too!...f course the <50 CC could keep her legal to boot!
Andrew

 

[5-7HEAVEN]

well, i'm really not interested in doing 55mph. i'd be satisfied with reaching 40mph quickly thru the gears, then easily maintaining that speed.

 

[just for kicks]

55mph on a pedal bike , I dont think so.
I'll be happy to cruise at a consistant 15-20mph with bursts up to 25-30mph max.
I figure I could pedal at a good 10-15 consistantly so going a bit faster with little to no effort is fine with me when on a bicycle.

When I want to go faster on two wheels I'll just jump on the cycle and go for a ride.

I feel an engine assisted bike should be able to start from a dead stop with a 200lbs. rider on it and get up to 30mph within a reasonable distance.

OK I do have a project going for the wife and it's simply a pocket bike engine with a CVT on her old mountain bike.
I hope it works and it is just an experiment for me.

If it works at all I'll be happy, if it works well I may put it on my bike

 

[5-7HEAVEN]

okay, another engine has my full attention:
http://www.davesmotors.com/store/product1088.html

ZENOAH G62PU engine, 62cc, 5.4hp@9500rpm/3.04lbs TQ@7500rpm, 87octane+, 6.6lbs weight...$349.00.

davesmotors has many other engines, and 3.5hp units sell for $159. the 62cc engine interests me because its power peaks from 1500-4500rpm LOWER than all of his other high-performance motors.

compared to the LIFAN engine/trans and BRIGGS&STRATTON/HONDA which weigh 43lbs+, this ZENOAH weighs less than my ROBIN 35CC engine!

well, it's cheaper than the 5hp HONDA, and in the long run,cheaper than prepping the BIKE to accept the 50lb LIFANS/BRIGGS/TECUMSEHS.

 

[5-7HEAVEN]

after research on this G62PU engine, it is not a good candidate. there is no clutch or flywheel setup, as its primary use is for r/c airplanes. there is a conversion kit, but it is rare, not in production and expensive.

hmmm, maybe a pocketbike engine.

 

[gone_fishin]

bolt-on-able-ity is a huge factor to motoredbiking, the large majority of folks just don't have a welder hangin out in the garage.

that's not to say the ideas here aren't good ones, i was merely addressing the "why" of the happy-time's success, IMO.