Insane???

Dirt Road Cowboy

Dirt Road Cowboy

Member
OK. I have a Cuyuna 215, 1 cylinder 20hp 2-stroke motor from an ultralight.

I'm seriously considering making a motorized bicycle out of it. I would use a go cart clutch of some kind, and narrow motorcycle brakes, rims and tires. I read that 21x1.6 would be about equal to a 26" bicycle.

I want it to be very light, and I do want to keep the pedals as a back up. The motor weighs about 40lbs.
I want to use it for on and off road explorations.

So, what do you think? Is this too crazy to work? Has anyone here tried something like this yet?

Suggestions?
 
That wouldn't be a motorized bicycle. That would be a particularly unsafe motorycle.

AGK took a ~20HP 4-stroke-powered cruiser to some races back in June, mopped up everybody on the track. Keyword: track.
When you have that much power, a bicycle frame is prolly not going to live very long. Especially off road.
When you press north of 30MPH on a bicycle, you're really on the cusp of disaster, IMHO
 
So, a specially built frame would be in order.

I would probably have to register it as a custom built motorcycle, but I really like the idea of something light weight, narrow and capable of being pedaled if needed.

I have seen the You Tube videos of the 50mph+ motorized bicycle with the Chinese 66/80 in it. The 20hp 2-stroke in my shed is just begging to be used though.
 
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Dirt Road Cowboy said:
OK. I have a Cuyuna 215, 1 cylinder 20hp 2-stroke motor from an ultralight.

So, what do you think? Is this too crazy to work? Has anyone here tried something like this yet?
Click to expand...
Build it and race it on Oct 22nd in SoCal against Affordable Go Karts
20 hp 4 stroke monsta bike in the Unlimited Class.

There might be a 20 hp ebike too if he doesn't go up in smoke and
a 160 cc 4 speed 4 stroke that makes about 23 hp even though
the rider isn't really a racer.
 
You could make up restrictor plates and double the head gaskets. Might tone down the power enough. You still would have a weight problem to contend with, 40lbs is a lot for a bicycle frame. I don't think this is a very good idea.
 
That much power and umph, could use a really HD frame and add lots of support as needed. Could add an alt for lighting. Lots and lots of options with that kind of power.

Post lots of pics and build safe! When in doubt, ere on the side of caution and build some thing cool.

Just an after thought, have you considered a pusher? Would solve a lot of head-aches.
 
I would make a few small changes, 1 and 1/2 water pipe for the frame, disk brake on a automobile wheel for the back, a motorcycle wheel with a large brake on the front, shocks on front and back and a killer front fork. Make everything smooth around the tank and handle bars, ( I almost cut my head off when I went through a windshield).
 
happyvalley said:
Yup a MC, so why fart around with pedals.
Click to expand...

I'd want to have them for a back up in case of break down, running out of gas, etc. Better than pushing!

My motor stands almost 15" from the bottom to the top of the plug. I don't think it would fit in a Worksman frame. It would be nice if it did though.

A pusher wouldn't work for exploring narrow, off-road trails.

I want light weight with power, and I just happen to have the motor already. Now I just need to come up with something for the frame.

I'm still doing lots of reading through the forum to get some ideas.
 
Hey, is that Cuyuna cooled with a belt driven fan like Rotax? If so, It has a smooth flywheel with no fins. Would be easy to strip all the tin and shrouds for that old school look.
De-tune the engine and exhaust some for lower rpm power, and shave a lotta weight too.
These are actualy snowmobile engines so you could prolly get snomo CVT parts cheap.
 
A 215 cc, 20 hp and 40+lb engine is outside the parameters of what a standard bicycle frame is meant to do, IMHO, plus it will probably end up too heavy anyway to pedal kinda like a moped.

Check these lightweight MCs, note the proprietary frames.

Project M85 - About the Prototype
FX Mountain Moto - 125lb 125cc - World's Lightest Off-Road On-Road Motorcycle - Superlight Supermoto Dirt Bikes

Or you could add a couple wings instead of pedals and not worry about the cops lol. Here's one http://skypup.wikispaces.com/file/view/IM001027.JPG/34774157/IM001027.JPG with the same engine: http://en.wikipedia.org/wiki/2si_215
 
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Not sure but I think that 40 lbs includes the re-drive and exhaust. If I remember correctly, it's a single cyl 2 stroke. I think just the engine alone is closer to 20 than 40 lbs
 
Maybe a frame similar to this?
ECCMB_Stretch_110cc_Lifan.jpg
 
OOps I meant to post a different one, built like a dirt bike, can't get the file size to work on it though.
 
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