Putting a gas engine on my bike

[MisterSteve124]

I'm putting an engine on my bike powering the rear wheel with a chain. I posted this one spudtech but I was wondering if any of you guys knew how big of an engine i need or should have to get around 20mph. If any of you have any ideas please post. I want to buy one tomorrow but I want to make sure I get one big enough. I'm probably going to get the engine off a weed wacker or chainsaw.

[rna_duelers]

The best way is to have the engine running directly onto the tire.With a wheel so you can pedal upto speed and maintian it with the engine.Use a chainsaw as they have the clutch which allows the drive shaft to not allways be spinning.

[MisterSteve124]

Well I was planning on not using the pedals because it would just be easier only having one chain on the rear wheel not 2 for the pedals and the engine. So if I do use a chansaw how big do you think I need the engine to be if I wanna go like 25mph.

[Flying_Salt]

They do sell these special wheels with an engine inside them, so you just pedal a little then it kicks in and you can go 15-20 mph. I think you can see ads in Popular Science

[MisterSteve124]

yeah I'm looking to do it my self and just hook up a gas engine and have it chain driven

[CpTn_lAw]

or.......if you want something a little extraordinary, you can buy a modelism pulse jet engine,and adapt it to your bike....these have up to 20 kg of thrust...imagine the top speed ...you could put the fuel in a container between your legs, and set the engine on, then slwoly increase the thrust...

[MisterSteve124]

no i just want an engine

[schmanman]

Jesus, why doesn't someone just tell him?

you want anywhere between a 3.5 to a 5 horse engine. a 5 horse will easily bush you to 45 mph on a bike.

[jrrdw]

That type of engine will be hard to mount to the bike, and will be oddly weighted.

[schmanman]

true. than a chainsaw engine should work.

[MisterSteve124]

I'm thinking about a 49cc engine on ebay. It already has a clutch and is meant for a pocket bike. Its only 50 bucks

[schmanman]

go for It. I'm sure you can find a use for it if It doesn't work out in the bike frame. even better, put a want ad in the paper asking about 70's-80's dirt bikes. you can pick one up for dirt cheap,they run great, and you can beat them to death and they just keep on going. I have a 76' Kawasaki ke175 enduro bike I got for free from a guy down the road. all it needed was a new spark plug<then I put in new oil,cleaned out the gas tank,airbox, and air intake, and It starts first or second kick, almost every time. It is soooooo fun!! It's a great, and cheap way to get into dirt biking, and If you get an enduro bike, you can legalise it.

[MisterSteve124]

yeah it wont work for a bike unless I have it mounted far to the right because the sprocket for it is on the left side. The gear for a bike is on the right. So if I mount it like over to the side far enough I can just run the chain straight down to the gear on the bike. But I don't have a welder so I would have to take it to a shop to get it welded. The other problem is look at the engine, it doesn't show a gas tank. http://cgi.ebay.com/NEW-F1-Mini-Pocket- ... dZViewItem

The only problem is if this doesn't have a gas tank what else could it be missing?

[jrrdw]

The kill switch/revlimiter/s.a.m./from looking at the picture thats all i can think off.

[MisterSteve124]

are any of those necessary for running it? I know the kill switch isn't but what about the revlimiter and the s.a.m. ? And does anyone think it will work mounting the bike to the right side of the bike? The only problem I'm thinking of is balancing.