What motor for 400lbs

[5-7HEAVEN]

At the entrance to my workplace's parking structure is a very steep ramp. There is a barrier arm that raises and lowers with every car entering the lot. There is no room to get a running start and I must wiggle past the arm, which is exactly where the ramp begins.

With twin engines, friction drive w/1.25" and 1.5" rollers and 5th gear of a 7-speed bike, I am able to tackle this steep ramp from a standing start.

With the same twin engines/friction drive on a single-speed cruiser, it is impossible to climb this ramp from a standing start.

That's with a 90 lb. bike, 25 lb backpack and 200 lb. rider.

 

[loquin]

Using a single speed motor, the gearing would need to be about 45 to 1 to get 400 pounds up a 14 % slope, with a Honda GXH50 engine, and about 50 to 1 with a Mitsubishi. But, that also limits your top speed to about 12 miles per hour! Single-speed motor-driven bike solutions are always a compromise between top end, and hill climb/acceleration.

In order to use a single engine, (less than 50cc,) you would need to have a means of changing the gear ratio if you want a reasonable top end, and still be able to climb that kind of slope, pulling that kind of weight. That's the reason that I mentioned a CVT. A CVT can automatically shift to a higher ratio as the load increased when you are going up hill, allowing the motor to operate in it's peak torque range. And, it can shift to a lower ratio as your speed increases, allowing a decent top-end. But, it isn't the perfect solution. It does cause some additional efficiency loss - a CVT and a jackshaft solution would lose about 10% of the available power when the belt is new, and progressively lose more as the belt wears.

Since CVT belt wear is important to the system efficiency, you need to make sure that your system isn't geared too tall to keep the CVT from shifting completely into the lowest gear ratio when you get up to speed. (If you don't the belt will wear faster.)

You would also want to use a motor which has a high torque output - 4-stroke motors tend to have higher torque, over a wider range than do 2-stroke engines.

 

[jawnn]

I just need some links to these motors....and it may have to be electric if I can't find one small enough to fit back of the seat with out sticking out the rear.

 

[5-7HEAVEN]

I just need some links to these motors....and it may have to be electric if I can't find one small enough to fit back of the seat with out sticking out the rear.

Function before form.

Remember, you're trying to push 400lbs. up a 14% grade. You don't have many options.

 

[duivendyk]

Come to think of it a GP 460 might do the trick for you,about 45cc,a real screamer,is good for 4.5 HP !! at 9000 rpm,a CVT would be nice to have though.Look at the CVT section for more info.

 

[stude13]

you might try hooper imports, the sell honda 50 and 70 and larger knockoffs. i have a 70 that has 49 stamped on the barrel. it is a three speed auto. these motors werer used on honda step through frame mopeds in from the sixties.

 

[5-7HEAVEN]

On second thought, a NuVinci hub and a Mits 43cc or Honda X50 should do the job.

And of course the engines will stick out like a sore thumb.

 

[duivendyk]

Of course including a Staton gear box also.Has enough reduction, but pretty slow on 14% incline,the only remedy for that is more power.Can the GP 460 be married to the Staton box ?.I believe so ,but not 100% sure.Not cheap.

 

[macarollo]

196cc honda clone from Harbor freight.... You'll get up that hill no problem!

 

[5-7HEAVEN]

This guy could use a push trailer like macarollo's suggesting. Maybe 2.5hp.