What kinda engine would be suitable for a moped bike?

I am looking into making a moped out of my bike to increase fuel efficiency. I am looking to find out where i could find a suitable engine within laws for NH. Around here, According to the DMV a moped or scooter must meet the following restrictions:

It must have an engine of 50 cubic centimeters or less.
It cannot exceed 30 mph on level terrain.
It cannot shift.
It cannot exceed two horsepower.

As i said, im not sure where to find a suitable engine to meet those criteria that i can scavenge. I am looking to make a chain drive bike not a roller driven due to inneficiency,maintence,and traction of the roller on the wheel being lack. Couldnt find any chain driven conversions on here. If you can offer any information it would be much appreciated.

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is this your first motor bike project? if so please learn from my mistake. I know that you have said that you did not like the "roler" or friction drive. When I set out to make my bike this way 6 months ago this was my intention to. However, I soon realized that the accuracy required for a chain drive was much more than I was capable of. On the other hand, friction drive was "easy" compared to a chain drive, and by the time I made my desicion I was done in a couple of weeks working a few hours a week. A weedwacker motor is typically less than 30 cc, you wont go faster than 30 and won't exceed 2 HP, meeting all the criterea. I have a friction drive bike, and it's performance was much greater than I first thought. True, it does rob some of your horsepower and isn't very ifficient, but contarary to what you said it has much less maintenance. fewer moving parts means fewer things that break, wich is good. I would highly recomend that you seriously consider doing a friction drive. You will be suprised at the results!
seandogue6 years ago
There's a company somewhere in the US that produces a front wheel motor...and I mean front wheel motor. The wheel itself (minus the inner and outer tubes) is the motor. carries its own gasoline, the whole shebang. I'd link you but I can't recall who they are.
trf (author)  seandogue6 years ago
Thats pretty cool. I wonder how much somethin like that costs lol. Seems like a pretty cool idea.
seandogue trf6 years ago
Well this isn't the one I recall, but it only took a couple of variations on my search to find something quite similar.

http://www.ohgizmo.com/2006/05/08/revopower-turns-your-bike-into-a-moped/
rickharris6 years ago
the French Solex bikes have used the front wheel roller for years it works well for them
trf (author)  rickharris6 years ago
Yeah ive seen alot of the rollers work sucessfully. Ive seen a few and they just creep me out. Im not really sure why. May have to try it for it tho. Have you ever made any type of a moped?
rickharris6 years ago
By the looks you may be in the UK if so you will need to put your creation through the single vehicle inspection just like a kit car.

Briggs and Stratton Lawn mower engines come out at around 4HP. BUT are not intended for high revving.

Weed eater motors are light and will rev quite high , 25 cc or so,

I have seen instructables and on the web people using large model aircraft motors driving direct onto the front wheel.

trf (author)  rickharris6 years ago
Im actually from NH in the United States, I figured those were what id hear but im looking for another other source with enough power. Im trying to avoid the front roller design since most people dont seem to have much luck with them. Thank you for the answer.