Scooter "transmission"

GoldenMotor.com

Agreen

Member
Feb 10, 2013
792
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18
Southeastern GA
OK, I give. I've been digging around and I'm not finding the applicable info I have been looking for.

Maybe someone can help.

http://www.ebay.com/itm/49CC-ENGINE...N03-/230729582204?hash=item35b88e067c&vxp=mtr

This thing says it has a "transmission". What does that mean? Does it shift? Automatically? Is it just a single speed reduction gear set?

Then I see this:

http://motorbicycling.com/showthread.php?t=57161

That one's got a cvt! Looks good, but where do you find one of those? Do you have to get it separately from the engine? My searches have all turned out a bunch of 150cc engines with cvts, not what I'm looking for.

I really just want to make a simple rack mounted motor bike. Clean and simple. Any input is helpful.
 

curtisfox

Well-Known Member
Dec 29, 2008
6,041
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minesota
Just look for Scooter parts. scooterparts4less.com is one,but there are others

The first site is a fixed gear reduction,and the second site is a CVT and are made for small engines,with 5/8" shafts.................Curt
 

Agreen

Member
Feb 10, 2013
792
11
18
Southeastern GA
I keep looking around, but I don't find much. CVT parts, yes, but finding the CVT has proven somewhat difficult.

I did find this:
http://www.ebay.com/itm/49cc-X1-X2-...rbox-U-TM03-/150744953787?hash=item23191973bb

But it says that it has a drive ratio of 7:1. That's not very specific. Is that the final ratio? Then what would the starting ratio be?

Scooterparts4less doesn't seem to sell complete CVTs, nor does monsterscooterparts. I looked around for a while, but all I can seem to find is a couple sketchy looking ones on eBay.

So this cvt bolts up to cag engines? I keep hearing bad things about cag engines, but how can they be so bad compared to china girl engines? Let's be honest here, the CGs don't have a good reputation either.

And I'd like to put this, rack mounted, on a Schwinn 700c hybrid. It's an aluminum frame bike and is very light. I think it would look pretty clean that way. Plus a CG probably won't fit in the frame.
 

Davezilla

New Member
Mar 15, 2014
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San Antonio Texas
I got one of those cvt's too and they will bolt to a cg engine but they're more intended for the piston port type pocketbike engines and some 4 strokes as well.
I got mine with intentions to make an adapter to fit on a CG engine but the setup would be pretty wide meaning I would need to offset mount the engine or let it stick out about 3 inches more on one side.
Then I came up with the idea to mount the cvt under the engine or somewhere else out of the way and run it by using a jack shaft with a pocketbike clutch on one end and driven by the CG engine's output sprocket. I would need to modify the clutch to engage at a lower rpm because of the built in 4:1 reduction in the CG engines, then play with the weights so it would "up shift " at a rate that would match the power curve.
Basically it would take a lot of work designing a way to drive it and make it shift in a way that would be beneficial to the engine, and these also have a 5:1 gearbox that reverses the direction of rotation...
Yeah, mine is sitting on a shelf right now while I'm thinking up a practical way to make it work on these engines. They do work good on the 49cc pocketbike engines tho...

Another one that caught my attention was the scooter transmissions that use a set of belts but these need to be shifted manually. I've seen a bike in here made by msrfan that has a 2 speed gearbox made out of centrifugal clutches and one way freewheels that would be practical, it's basically an up scaled rc transmission but it looks really cool the way it's setup and how it all works...
 

Davezilla

New Member
Mar 15, 2014
2,705
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0
San Antonio Texas
This is the one I saw in here that looks practical... something like this could be driven off the CG engine by running a short chain off the engine to the transmission's input shaft... it would need to be designed to shift at the right rpm to match the engine's output to get the most out of it as well as setting up the gear ratios where they would be useful... http://motorbicycling.com/showthread.php?t=46564
 

Agreen

Member
Feb 10, 2013
792
11
18
Southeastern GA
Really I'm not trying to do anything. I'm looking for something to do and have been considering motorizing my schwinn trailway. I dont know what year it is, but it's an aluminum hybrid.

So for that bike ive been tossing together a slew of ideas but nothing's concrete yet. It's a very "efficient" bike; low rolling resistance and very light.

One idea was to go electric, but those batteries are very pricey! I don't want to use a china girl, because ive done that already and i don't like doing the same old thing. So I'm considering a pocketbike engine with a cvt on a sturdy rack. Fully automatic is my goal. Pull start, twist throttle, go. Pedal assist when necessary, but not pedal takeoff.

Maybe.

I'm not sure yet.

Just thinkin out loud.
 

Tony01

Well-Known Member
Nov 28, 2012
1,729
1,721
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sf bay area
I've built only one motorized bike, but I've tried every type of transmission out there on it (derailleur shifter auto clutch, derailleur shifter manual clutch, single speed auto & manual, chain and belt drives, on primary and secondary, belt CVT, and full chain 2-speed auto).

Since you want auto, you pretty much have two options:
Heavy duty,

and

light duty.


It pretty much all comes down to the performance you seek, and your engine HP. If your engine is pretty weak like a 50cc 2-stroke, you can get away with using bicycle components like the SBP shift kit or the LR shifter. But if you go with a torquey 4-stroke like the lifan 118cc or something bigger, you'll need something heavier duty like my 2-speed auto (see older thread) because these motors will break bicycle chain very fast.

A CVT can be heavy or light duty, but both will suck up some power. More power as the belt wears.

Me personally.. I wanna find a high-revving 2-stroke or even rotary motor and patch it in to a SA 3-speed fixie hub. Engine braking and lots of high rpm HP. THE three speed, hook it up to an electronic shifter that can shift automatically or by paddle shifters. Something that would give a lightweight bike that I could easily take with me on the train, or carry upstairs.