snowmobile engine in minibike idea

[TeamCheap]

So I was just sitting here thinking how I could make a snowmobile engined minibike.

I think an old 440cc engine would work nicely and probably have decent get-up-and-go power.
Engine cooling would be a bit of a concern but then again I doubt it would be an all day cruiser/rider machine.:smile:

I'm thinking a custom frame of course with the engine mounted parrallel with the frame and a fat slick tire on the rear, wheelie bar, hardtail with a spring suspended seat.

I wonder how much engine torgue would effect the bike when the throttle is nailed with an engine mounted inline with the frame.

Oh well its just an idea but would be a fun project.

 

[Neck]

GET ON WITH YOUR BAD SELF!! Build it! put dual expansion chambers on it! Make it cackle.
I LOVE 2 strokes, better make it long and add wheelie bars cause the mid range hit will definatly stand it up "QUICK"

 

[mybiz]

had a 340cc on my dunecycle it had some neck snaping power:thumbsup:

 

[AKAxAUTO]

it should be pretty wild. :thumbsup:
you should build it.

 

[minibikedude]

I would not mount the engine inline. I would mount it parallel to the frame it would be easier to run the Torque converter and chain to the wheel. Keep the engine as forward as you can it will scream with a 440 on it. The other thing you will have to work out is the exhaust so you do not fry your legs running it to the back of the bike. Go with 12 inch wheels off a Rupp they would handle the speed better. I do not think it would be a cheap build to do it right but it could be done with a snowmobile engine just way more power than needed on a minibike.

 

[mybiz]

ya wouldnt be a good idea running the motor half cocked and tire and rim size dont matter that much but not to small look at minidragbike wheels and it wouldnt be a good idea to use a spoked wheel

 

[mrfreyguy]

I had that idea with a yamaha bravo engine. I'd like to see it when it's done. It's gonna be sweeet.:thumbsup:

 

[Oldsalt]

Are you going to use a 440 Polaris engine? You mentioned a cooling problem you need to deal with. The Polaris is water cooled so a tank, even a thin one under the engine, would be needed. If the engine does not have a fuel pump you will have to supply one or put the fuel tank on the handle bars. That is what I resorted to, on a 200cc Gilera engine in a mini, because the engine was so tall that the tank couldn't be reasonably put anywhere else without a fuel pump.

Do it!

 

[minidragbike]

My buddy has one, he haven't finished with it yet, but it's in the process. he plans on running that big TC that comes with it. I also think it's a 440cc version too.

 

[TeamCheap]

With the engine's crankshaft 90 degree's (perpendicular) to the frame it would stick out a lot and then I'd have a drive belt on my leg but it would be easier to hook up the rest of the driveline.
With the engine inline (parallel)to the frame I think it would be tucked in a bit more and I could just use a 90 degree 1:1 gearbox - combination - jackshaft.(Although that might be a weekspot)

Liquid cooling would be best but to keep it simple and light I'd go with an air cooled engine.

For the tires/rims I was looking at those chopper mini bikes since they have a decent sized back tire and are easy enough to find around for sale cheap.
Something like this as the donor Pocket Chopper


Oh its still just an idea but I think it could be a fun project.

 

[oldsledz]

How much HP are you looking for? most early 70s fan cooled 440s put out 24 to 32 HP.
A 250 Yamaha Enticer and 277 Rotax both singles and put out around 26 to 28 HP.
The singles will be much easier to keep cool , lighter, and have more low end torque than a 440 twin.

 

[TeamCheap]

What started me thinking about this is I have an old polaris trailboss ATV that I wanted mainly for the 4x4 driveline but it has a single cylinder 250cc engine that runs but I thought maybe a twin cylinder minibike would be fun.
Maybe I should just go cheap and extremely easy and buy a DB and fit that 250cc engine in it for a kick.

Right now I just have a few idea's and as soon as I am cut loose from this house project I will be making one.

 

[Mark G]

Check out this rocket. The details are a little fuzzy but I think it's a 440 Kawa/Yama/Honda or something like that. I do remember it was a street bike motor though. The frame is all custom, the only factory part is the steering neck. :thumbsup:

 

[jeep4me]

I saw one of these at the mini bike show in Ann Arbor last year, 2008. It had a 440 in it. He used a Heath Kit Hilltopper frame and the engine took up every bit of space and then some. He said he only rode it a couple of times and that it was scary fast. Sounded really nice. Good luck with it.