CVT Got a pocket bike cvt xD

CrazyDan

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#1
Just bought a pocket bike cvt from a buddy who had it just lying around for years for $25 :cool:, appears in full working order.
It's the CVT-B as referenced in this thread: https://motoredbikes.com/threads/the-cvt-faq.19772/.

It reverses rotation so I'll have to figure out how to get the power to the wheel. I'm think about doing an overall reduction of 28:1 to 12.8:1 for good acceleration and top speed. Would give me a 42 mph top speed if I keep it under 7k rpm (I'd have to put the governed flywheel and magneto back on) or 54 mph if it can hang to 9k rpm :p. It'll do it's variator thingy between 14-33 mph.

Hope it works right :).
 


Frankenstein

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#2
Can you post a picture of it? When you say it reverses the rotation that doesn't seem to match what would appear to be ctv-b, unless I'm mistaken that will rotate in the same fashion as the engine, usually counter-clockwise.
 

CrazyDan

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#3
I'll get pics of it tomorrow. The gear box attached to the driven shaft further reduces reduction and reverses rotation for a total of 7:1-3.2:1.
Its the part attached with 5 bolts around the output sprocket in this pic:

It has 2 gears meshing inside that reverses rotation.
 

CrazyDan

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#4
This is the other side naked:

You can see how the output sprocket is in a different location from the driven pulley shaft.
 

Frankenstein

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#5
I'll get pics of it tomorrow. The gear box attached to the driven shaft further reduces reduction and reverses rotation for a total of 7:1-3.2:1.
Its the part attached with 5 bolts around the output sprocket in this pic:

It has 2 gears meshing inside that reverses rotation.
I see, thanks. There should be a thread dedicated to these reversing trannys, it's actually somewhat helpful to the motorized bicycle community being we naturally use a right hand drive which requires clockwise rotation, for most engines (including the happy time) turning the engine's drive shaft side to the driven side of a bike means it rotates in the wrong direction. These unique ctv help a lot of you want to design something or just simply make use of a jackshaft crank without having to use an actual jackshaft, cuts the chains down to 2 instead of 3 too (unless the ctv uses a chain of course, but either way it's still convenient.)
 

CrazyDan

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#8
This CVT has the advantage of being able to be used on single speed bikes and still run like it's geared without fumbling for the shifter knob and rolling off and back on the gas with each gear change. It's a shame they, and their parts, are no longer produced...
 

bakaneko

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#9
crazydan, do the right side HS-142F engine with the reverse CVT with a SBP freewheel. I have been wanting to do this and make it into a kit or guide for others, but I am working on a new eBike design so no money and time. would be great to see a build log and guide on it.
 

Frankenstein

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#10
This CVT has the advantage of being able to be used on single speed bikes and still run like it's geared without fumbling for the shifter knob and rolling off and back on the gas with each gear change. It's a shame they, and their parts, are no longer produced...
Which, the one above is still manufactured, no? Referring to a belt ctv maybe? I'm interested particularly in the cvt-b, if it reverses and is an actual cvt, meaning it changes ratios somehow while riding, then people with some single speed bikes could jackshaft but not in vain. I could imagine a 2 or 3 speed internal geared hub linked to a ctv that changes between 2 ratios, would give a decent gear spread with a simple 2 or 3 position switch or knob.

2 would be better, then the flipper only has 2 positions on the bars, up or down, very easy to manipulate without having to think about it and zero guessing, as soon as you feel it you know the gear. Would be a good way to "jackshaft" without the shaft as I mentioned before, less failure points (but technically more if you count the components in the ctv itself, but it can be replaced as a whole unit relatively cheap, and of course you get to use a 4s instead of the china turd. I have been thinking about this gear box because it would make for a really good 4 stroke motor in my bike. I can weld a half inch pitch sprocket onto that 35 gear and keep using standard bike chain, or I could get a 35 sprocket for a go cart and mount it to a sbp chainring.
 
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