I need help with something.

Only thing I could think of is replacing the swing-arm rod/pin with a jackshaft. With the Chinese motorized bike motors you'd need to change the side where the power comes out the motor.

I'm not saying it would be easy, you just about need a machine shop to do what I'm suggesting but I'd bet it works

Use a 50cc HS and put a spring loaded tensioner on the chain, put the motor where the batts are. Its doable with some fabrication...............considering the weight of that frame maybe use a 79cc or 99cc? HF motor.

Maskot said:

i found this bike chain tensioner but can't find it for sale anywhere...

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That is a cool looking tensioner.
Would work well on the pedal side.
Thank you for the pic.

I would sell it and start from skratch- if you want small little wheels for a build that may be a nice run-about but not very quick- then use a 20" stingray- or get a cruiser with a spring seat post and front shock

Maskot said:

I am trying to convert my crappy little electric dirt bike

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This is a very true statement only because of the attempted conversion, it is a perfectly good ELECTRIC BIKE..........


Even if you have the tools and the ability to get this conversion done you will not have much of anything for all your labor....and busted knuckles IMHO.

The entire mechanical make up on that little bike is way wrong for these China Girl engines, the brake is on the wrong side, the drive sprocket on the wrong side, the swing arm will wreck your ability to make an easy simple drive system, it's just not a good platform for these engines and would maybe give you a 15mph cruiser with that tiny rear wheel & tire........

What I would do if I really wanted to have this thing gas powered would be to just build myself a pusher trailer with a HF 79cc or one of the up and coming 99cc engines and then you could get rid of all the electric stuff and still have that good rear brake and have something that could be geared to zip you up and down the street @ 25-30MPH possibly if set up right, a very small pusher could be built for that little bike, and would solve all the headaches your having right now that will not end IMO on that little motor bike.

OR better yet just put a China Girl on a BICYCLE if you dont like the pusher idea...then make it a legal MB that way....

Below is a couple of links to a simple pusher set up that could be put together for your current Motor Bike....

http://www.youtube.com/watch?v=pSngBqZd9VA

YouTube - Morotized trailer in Hawaii pushes bike 35 mph

YouTube - Mike's 196cc push trailer demo this kid has a couple things wrong like on the 8-9hp when in reallity they are rated at 6.5hp stock, but he made himself a nice little ride here accept for that no-flat tire no way that will last very long.

Anyway just some ideas and my opinions, nothing more nothing less and I dont claim them to be worth a lot ta-boot....


Peace

It's possible that you could do that, but this still doesn't address the other issues with the very small tire which will gear it very low and make it very slow......, you will still need room for the engine and will need to fabricate the mounting system....ect.....ect.....ect!

It all depends on what you are personally able to do mechanically, and if you have the tools to do all this or not, that would not be a project I personally would ever attempt, when I could spend less money and much less trouble and put that engine on a bike, but if you have the tools, the time, the know how, the money and the desire to have an engine on that little bike I say go for it, but if you cant answer yes to all the above questions....I say build a bike and forget that electric bike conversion idea.....

Just my opinions nothing more nothing less......

Best wishes, Peace

Maskot said:

the electric motocross bike i have has leaking batteries since a new set of batteries would cost $123, I just figured why not make it gas powered. I would flip the tire around and re-mount the brakes, would that work?

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DaveC has the right idea. A jackshaft would allow you to gear it as fast as the motor would pull it. It would have to be at or very near the swing arm pivot. Lots of fabrication. Sell that thing and put the money towards a real motorbicycle. A pusher would be cool. Stone reliable with no chain problems and you wouldn't have to tear up the bike.