not sure if this is the right place. i was wondering if any1 here had any info about what engine kit etc would be good. i dont know if this sort of thing is frowned upon or whatever. i have a new 05 specialized hardrock and wanted to know what gas powered engine if any would go good with this bike. thanks

google is your friend. Old trick ....but new again.

Go to a motorcycle dealer. They have lots of 'special' bikes that are powered by a gasoline engine. I have two, myself. Delightful machines.

eff u

Such a witty response. You should look into a career in public speaking.

What a rook. Just go and get a scooter or like the other person said, get a freaking motorcycle.

gas powered bicycles... more commonly called motorcycles.

This is what you are looking for.

https://cyclehappy.com/honda_racing_h...motor_kit.html

https://bikeengines.com/

If it has pedals, it's called a moped.

look for bicycle engine on Ebay. There are some 50 and 80 cc twostroke engines that look like Whizzer knockoffs for sale.

Give a little, take a little.

Three words: Bush's Baked Beans.

here's a cool engine that I mounted on my bike .

I've got a Kings 80cc motor that works nicely on my touring bike. The problem was, I bought it for my restored Columbia Cruiser which the webpage said it would fit, and it would have. Only problem is that it would have neccesatated drilling holes through the frame, which there was no chance in hell I was going to do. So, I needed a bigger frame and I chose my touring bike. Unless your rock hopper is pretty big, there is a chance you might need to drill some holes in the frame.

I don't want to discourage anybody from building up bikes like this, because its a good and cheap source of experience for those who have don't know much about motors. Don't get me wrong, I have a lot of fun with my 80cc touring bike, but these things aren't fit for daily commuting. A frequent problem you will experience is the chain pulley getting misaligned, and other jamming and stuff is a common occurance, at least in my experience. Also, bicycle tires are not meant for the continuous speeds these things can put out. If you wanted a very cheap daily commuter, a mini bike would be good. If your just looking to have fun, motor kits are great.

Exactly. A bicycle is engineered to be a bicycle. If you want a small gas-driven bike for commuting, get a moped or small motorcycle or scooter. The package will be engineered for higher speeds and heavier use - shocks, stronger wheels and brakes, more durable tires, built-in lighting systems, etc.

I have had a 48cc 2-stroke on a cruiser bike for over a year now. Over 1,000 miles and no breakdowns yet, but I still get nervous if I go more than a few miles from home. These things are very hard to pedal with out the motor running. It's best use is for carrying heavy loads on the Bob. Makes grocery shopping a breeze. The biggest problem I have had is broken spokes from the drive sprocket, but it appears that this has lessened now the the spokes have worn themselves into the sprocket a bit.

I did the montauk century with my 48cc engine bicycle from Queens NY to Montauk and back on 5-21-06all together 220 miles and I broke three spokes all on the cluster side or right side and I think that the kick of the engine causes these spokes to break because it happens only to the pulling spokes as opposed to the pushing spokes. so now I think I will loosen up the spokes on the cluster side a bit to see what happens.

Somebody was making a conversion kit to allow a weed-whacker engine to power a bike. There was a centrifugal clutch assembly that replaced the bolt-on "arm" of the weed whacker, and a mount arrangement that you attached to a regular bike luggage rack.
A motorcyle-type sprocket replaced the lowest gear on the cassette.

Looked like a cute idea, but I don't know about that screaming 2-stroke behind you....

Check out the French Velosolex 2 stroke powered bicycle.

I think a better option would be an electric assist kit.

Gas engine on a bike? How horrid. Take my pleasant fresh air ride, and sour it with motor noise and pollution coming from the bottom of my own bike frame?

Do a search on the forums for an electric assist kit. There's a girl who posts here regularly who uses one, but at this exact moment I'm "drawing a blank" on the handle.

Here it is, if you can wait.
https://www.revopower.com/

In the early 70s I saw somebody in my neighborhood with a 10cc model airplane engine mounted above the front forks, with a propeller about 9" dia. This was very noisy, but no problems with transferring power to the wheels.

So I'm a girl now?

So I'm a girl now?

heh...sorry. I gathered from both the handle and some of the posts that you are female. Didn't mean the "girl" to be derogatory.

Just trying to point the OP in the direction of something better than a gasoline engine.