Flattest RC style motor?

Hmm, I really like this idea. The motors that handle only 1000w are pretty small and have a KV of around 500 (rpm per volt). The best way to integrate one of these motors, IMHO, would be to wind it up, and then use a clutch that grinds down to the rpm of the drivetrain while accelerating. What you really want is a motor with a lower KV like the guys with the Astro 3010, or Gary's Hacker that is mechanically tied in with your throttle. I have a Hacker and it measures about 2 1/2" long without the shaft, and is about the same diameter around. Anything smaller won't be worth the effort. What size beast are we talking? I can see it helping anything up to 80cc, after that would be better served with aftermarket pipe, porting, polishing, etc... Just my 2 ¢, I could very well be wrong. How do you plan to implement the hybrid system?
 
what I have is one of those thin HT motors that fits in the triangle. they make ok horsepower, 1500 watts worth or so, but are low compression. the big problem is they have no grunt, and aren't suppose to be used to take off from a stop.

What I planned to do was bolt this directly to the crank shaft in a modified pull starter housing. Then use it for low end grunt, as well as the starter and alternator. power would come from a single dewalt group of A123 hidden in the frame

the only trouble is I have maybe 4cm Maximum depth before the pedal would strike it. It can be up to 6cm wide, though.
 
Very cool project. I had one of those and was impressed with the speed, but I felt very illegal riding around on it so I sold it and ended up here :) Anyway, I don't think you will find one that puts out the proper rpm in that size. However, if you search for "gearhead" on ebay you will see some servo motors with gearboxes that run on 24 volt and have very high reduction (120:1). Run this to double sprockets off the crankshaft might be feasable up to about 10mph. I'm just guessing here though. Do you have a picture?
 
the problem with the reduction is trying to use it as an alternator. I think it will have to be 1:1. that should be fine for a 100kv or less motor, though. And I can rewind the motor if I can find one that fits physically. 1000w was a wild guess. It only needs to be 200W to operate, but the bigger the better.


This is the same model bike, and the motor is similar, but with a diffrent side cover:
1903-800_w.jpg
 
Not to put you off your neat idea, but for about $650 you could get a NuVinci CVT and drive it with a jackshaft conversion like the ones at sickbikeparts.com This picture is one of the neatest conversions I have seen, but to be honest I still cringe at the thought of a 2 stroke on such a lovely bike. It's unfortunate there are no nice compact 4 strokes as cheaply and readily available as the Happy Time engine.

Another idea is to make your own motor, although your 40-60mm limit will have you working hard this way:
http://endless-sphere.com/forums/viewtopic.php?f=2&t=6762

My own idea is to build an electric motor like that into the front chain wheel, and like you say hide the batteries, a real sleeper bike. But I think getting a motor to preform in the 0-100 rpm range is a big ask. Worse requirements than that of a hub motor. So internal gearing would probably be needed and that puts it in the complex department, for now.

Dean.
 

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Bell type out-runners are the flattest type of RC motor. I have on about 3/4" thick x 2.5" diameter that is rated for 800w.

However, if you have a gasoline engine all ready installed on the bike, and you are just looking for an extra 1-2hp, that's a cakewalk. Bump up compression, port the head, setup good valve seat angles, mod and tune the carb etc. You can do all these things on a little 1 cylinder engine for maybe ~$100 if you have a dremel and basic tools.

I'm guessing this is a 50cc engine? If it's a 2-stroke, you could very likely double or even tripple the output. If it's a 4 stroke, expect to easily make 50% more power for minimal costs. You can also improve fuel economy while making more power, and drastically improve the response of the engine.
 
liveforphysics said:
Bell type out-runners are the flattest type of RC motor. I have on about 3/4" thick x 2.5" diameter that is rated for 800w.

Got a link to any like that? I haven't found any in my searching.

I'm not looking to add any speed to this. its the 80cc kit, and living in Texas, Hills aren't an issue.
what I'm looking for is a motor I can use for:
A starter.
An alternator (or generatror) capable of running a DOT legal head and tail light, and a motorcycle horn.
An Assist motor to help accelerate at low speeds when the motor can't Like pulling away from a dead stop.
Completely hidden from view.

I looked at the NuVinci designs, and the jack shaft setup to use them, but its another $200, and added complexity. it also makes the bike illegal, as the law here mandates that you not have any ability to shift gears on a moped. I have a title and plates to register this as a moped.
 
It's the lowest KV bell type that hobby city sells. I think it's a 12 pole if I remember right. It's just been sitting on my project shelf for a year. It takes a few hours to filter through the list of motors sold at hobby city, or I would try to find the link for you.


I don't know how well using it for a generator would work for you, but I do know that I've stuck 150w lighting coil kits onto my off road dirtbikes, and it's very easy, and it runs the dual bulb HID lighting kits I use like a champ. They cost like $65 on fleabay. As far as a starter goes, does the bike have a clutch?
 
I have the same idea for mopeds here in Iowa. When they changed the legal definition of bicycles to include electrics, they deleted the engine size and power restrictions for mopeds.

So potentially you could take a 50cc moped and graft in an electric drive to produce crotch rocket acceleration and then use the excess ICE power to charge the batteries. Moped legality, range, and economy (well, most of it) with enough acceleration to mingle safely with 30 MPH traffic. If you think you could be convincing, you could fake pedalling and go 35. Or you can just register the moped as a motorcycle and go as fast as you care to.

Taking the idea further leads to something like a 100cc motorcycle that can do all legal speeds but can benefit from acceleration assistance.

The possibilities I've thought of are connecting to the crankshaft, a gear-reduction motor directly to the rear wheel ala ezip, a hubmotor, or even friction drive. You could feed a lot of amps into the acceleration because the motor would have a chance to cool off when the ICE motor takes over at cruising speed.

For your situation I would think amping the hell out of a rear hubmotor and using regen braking and power generation at speed would meet your performance, stealth, and cost requirements. How many batteries you would need would depend on how many amps you'd be pulling and how often you get charging opportunities between accelerations.

Oops, just read your starter requirement. I'd assume the ICE motor has a centrifugal clutch? Maybe you could add a lockup to it and then spin the electric drive and use the lockup to start the ICE.
 
I like the hub idea best. You could pickup one of those 350 watt rear hubs, overvolt it with A123, maybe 15s2p, with a regen controller. In fact, you might be able to brighten your lights with a knob controlling regen. Can't you just use the electric motor accelerating to start the motor if you dump the clutch? That's a classy bike, how much did you pay?
 
I got it from a guy who had it as part of a display for his show car. he dumped it for $200 when he had his car repainted, and it didn't match any more. it had never been ridden. It has now, though! :D
Hub motor could sort of work, but its too much extra weight and too many compromises.15 pounds for a controller, hub motor, and batteries VS maybe 1 to 2 pounds for a more powerful RC that can be hidden totaly from view.
 
Yes, the weight factor would be nice. If you drive through the crankshaft that means you are also driving through the clutch, and if its not up to the low speed torque…

A parallel sprocket at the final drive of the engine might be the place to add electric drive in, but you would still need a clutch lockup for starting. Have you considered using 2 smaller motors and esc's? That might help you acheive the width dimension and might not cost much more than 1.
 
So basically you want to take off from a standstill, and want lights. I'm not sure what DOT legal lights are but did you know you can get hand held torches that can melt plastic rubbish bags and catch news paper alight ?

So on to the take off from standstill........ I remember guys on a goped forum I think it was saying the belt drive CVT is legal as you are not the one shifting, not sure how true it is, I guess if belt CVT mopeds are legal in your state then it has to be ok to use one. They are made for pocket bikes and may be adapted, or just use the pocket bike engine as well.
 
what rpm does this little 2-cycle run at? 8-10krpm? http://www.hobbycity.com/hobbycity/stor ... oduct=5144 is interesting. Looks like the body is ~54mm long so would need a bit of modding to get down to 40mm. At the very least the core lamination and rotor would be near the right size for making a custom motor.

Lawson
 
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