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Post by lain on Aug 19, 2015 17:32:50 GMT -5
Is it possible to either hookup the output shaft of a standard 139qmb 50cc engine to a chain for a rear wheel on a bicycle or old moped, or maybe a cvt to chain conversion with gears? I know it sounds crazy, but I'm not technically sane.
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Post by jtron on Aug 19, 2015 18:01:18 GMT -5
It sure would be sweet, but probably pretty expensive. I think one modern brand sells 4 speed scoots I forget which tho....cvts are pretty convenient but they do steal a lot of power and make changing the gearing a little bit harder than simply swapping a sprocket out
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Post by jtron on Aug 19, 2015 19:47:15 GMT -5
Oh yeah. I was thinking of the genuine stella. One of tbe only retro style scoots that I like AND its a 4 speed manual pretty sweet
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Post by horace on Aug 20, 2015 17:08:54 GMT -5
I am not real sure that would work very well.......
Indeed it sounds like a neat idea but, not very practicle IMO.
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Post by cyborg on Aug 20, 2015 17:28:21 GMT -5
i have a stella,,,got rid of a vespa et4 for it,,like the manual box way more than a cvt,,,theres no neutral when tuning the engine,,,they do waste a bunch of power that gets turned to heat,,,after some runs i couldn't even touch the belt cover on the et,,,,my mind has been working on a auto clutch off the crank with a 5 or 6 speed derailer system like a road bicycle,,,i think any decent running gy6 150cc would be able to reach 70-80 mph and almost double the mpg,,but its money for developemnet and most importantly the time,,,it would be worth it just to rip past the harley crowd in the canyons and smoke them solid,,,
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Post by cyborg on Aug 20, 2015 17:38:04 GMT -5
eliminating the cvt was the main reason i was going to jump on the bms bi-metro instead of a twist and go,,,i still am thinking of it,,,,,auto clutch with 4 speed box sounds like my cup of tea,,,i really do want one of those silly things,,
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Post by cyborg on Aug 21, 2015 14:06:51 GMT -5
As a side note on the Bms bi metro,,, I was looking for performance parts for it and found a 150cc 4 valve complete balanced / blueprinted engine for it,,,,this could get interesting,,, if I can find one used with low miles or better yet one with a blown mill,,,, things could get very interesting in a hurry,,,
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Post by scooter on Aug 21, 2015 15:56:11 GMT -5
As a side note on the Bms bi metro,,, I was looking for performance parts for it and found a 150cc 4 valve complete balanced / blueprinted engine for it,,,,this could get interesting,,, if I can find one used with low miles or better yet one with a blown mill,,,, things could get very interesting in a hurry,,, The Bms bi metro: said to be "Powerful enough for men, but smooth enough for women." Its original name roughly translated to "the city scooter that goes both ways".    |
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Post by lain on Aug 21, 2015 16:26:05 GMT -5
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Post by horace on Aug 21, 2015 17:41:56 GMT -5
My first thought reading this thread was a chain bouncing around on the CVT  On second thought , with something like a Jack shaft and a bit of creativity this is absolutely doable. Still not very practical but a VERY interesting project. Cars go Manual instead of automatic all the time. The difference being, they are (somewhat) made to do both. Next your gonna want front wheel drive..... Madness I like the idea!!!! |
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Post by lain on Aug 21, 2015 17:59:20 GMT -5
Front wheel drive? Hmm now wouldn't that be interesting! I'm not getting into that though, haha.
All I need now is to get someone to weld me someplace to bolt on a 150 engine to a bicycle or moped and a chain and rear wheel sprocket, or rear wheel with sprockets...
I also need to think about somehow getting disc brakes onto a bicycle or moped...
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Post by horace on Aug 21, 2015 20:16:17 GMT -5
What about the gear ratio?
I know, one step at a time......... This will come up at some point though. Just sayn
Got pics ?
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Post by phssthpok on Aug 21, 2015 21:12:50 GMT -5
I've applied a LOT of free brain-time to this idea in the past. What I've come up with so far:
1: No clutch on the output shaft. If you plan on using a typical bicycle derailleur, then the chain needs to be in motion in order to change gears....which you will need to do (downshift into 'first') at stoplights, etc. Retaining the clutch in the rear part of the drive-train allows for the chain to spin freely at idle to allow for gear changes when not moving.
2 a: Manual shifting? Fairly easy to engineer the mount points and linkages.
b: Autoshifting? yeah.. I thought that one out too! Roughly explained, I'd have to output sprocket replacing the outer face of the variator while retaining the inner face and the ramps/weights that make it work. Between these would be a stiff spring (akin to the large spring in the clutch-pack on the rear) standing in for the belt tension. Have a lever which actuates the derailleur 'ride' the edge of the face of the variator. Presto! Engine speed increases, variator moves out, presses on the lever moving the derailleur, and shifting up! Engine speed reduces, and the system reverses, bringing you back to first gear!
3: The necessity of a much tougher drive chain to handle the 7-10 HP of a typical GY6 150 would probably limit you to a three-speed gear-puck in the rear.
4: An intermediate gear reduction shaft may be required to bring the operating RPM of the chain/drive gears to an acceptable level. Packing all that into a CVT drive cover will be a challenge.
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Post by lain on Aug 21, 2015 21:21:37 GMT -5
Well with the sprocket I found earlier, I was thinking more along the lines of keeping the cvt but putting a sprocket on the output shaft of the cvt (rear wheel shaft after final gears) and attaching it to a wheel via a chain.
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Post by phssthpok on Aug 22, 2015 6:04:12 GMT -5
Well with the sprocket I found earlier, I was thinking more along the lines of keeping the cvt but putting a sprocket on the output shaft of the cvt (rear wheel shaft after final gears) and attaching it to a wheel via a chain. You can purchase short case gy6's for buggies that are already set up for that (sprocket on final drive shaft. HOWEVER...bear in mind that the diameter of the rear wheel will require a totally different rear chassis. Much like the engine case on a normal gy6 prevents up-sizing the wheel due to interference, the output shaft will intrude on the center-line of a single wheel (especially since you'd have to extend the final drive shaft to match the rights-side orientation of a bicycle wjeel's driven sprocket). It might be a viable option for a tricycle though. |
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