CVT CVT Project On Restored Cruiser

[Nuttsy]

I know some of you have seen this before. This is where I first saw it. However, note 2 things. It is the same CVT we're talking about 'cept with the Chrome plastic cover instead of the black one like mine. The 2nd thing is look at that ginormous sprocket on the rear wheel! It seems to go off the line alright, but with that GX35, I doubt it has much of a top end with that setup. You can't tell from the short vid and the way the guy is riding. I guess its what you're looking for. Most of my commuting is mile or more stretches with no traffic lights, stop signs etc., so I'm more interested in cruising at a decent steady speed (without going too crazy). If I were in a more city-like atmosphere, with alot of constant stop and go, I might want to have a huge sprocket on the back like that guy too. And too, I don't mind pedaling to get going or even helping on steeper hills, Its just a little harder on a one speed bike than a 21.
I'd like to make a vid if only I knew more about it. Nuts and bolts I can do; technology, not so much. lol
WC
http://www.youtube.com/watch?v=0T0jJkqMfPg&feature=PlayList&p=430C087288357E2E&playnext=1&index=12

 

[DetonatorTuning]

Nuttsy,

your points echo what i was trying to get at.

you need to build your total overall reduction so that your engine will keep pulling all the way to redline.

the advantage of the CVT lies in it's abiblity to "underdrive" that ratio to give you start off acceleration.

i'd think that much like my GP460 your engine has a mid-range sweet spot just above the advertised torque peak. i gear to be running 35-40mph right there. that lets me shift down for start offs and hills and shift up for super economy cruising.

your 4 stroke is going to give you alot of flexability due to good torque characteristics.

i agree about the bike in the vid. i doubt it tops 25mph. and i know what you mean about doing vids, i'll have to hire my daughters boyfriend to do one for me !!

steve

 

[Nuttsy]

DT,
Seems like it's you and me here pal. haha, and the guy that got swallowed by robots. AGAIN. hmmm. Mysteriously absent...
Anyway, trust me, I ran ALOT of numbers before I dove into this project. I re-checked and it was in fact a gear ratio calculator I downloaded from THIS site. It was published by one Jim Sitton. Sorry, I've got it on my machine but can't locate the link. However, I do NOT trust this guy's speed calculations. Especially now that I have and actual working model.
Anyway, using the calc. or even basic math, and if you believe the advertised gear ratio of 7:1 at low end, then with my 12/44 final drive, I would have a 25.6:1 on the low side. And assuming a 2:1 ratio at the high end ( I no-how believe these things can hit anywhere near 1:1 just from observing the belt at various rpms) , an equivalent 7.3:1 in full zip mode, I'm thinking those numbers work for a WIDE range of ratios. Since it seems everyone here is advocating an approximate 18-ish:1 for a single speed setup, I thought I would be in good shape. And in actual practice, seems I am. I'm really happy with the CVTs performance on the same engine over the friction drive (the only thing I can compare it to).
NOW, that's not to say I won't be playing with different ratios in the future. I may try a 10/44;12/56; or beyond but for now; I'm good. And the BETA portion of my system is over. I put on another 10 miles the last couple of days and it seems ready. So, now I'll be taking it apart and painting stuff and replacing the fender in the rear and working on the lighting.
All that will be killing me as I really have been into riding this beast finally. Yet I'm hoping to have it all back together for the next Tampa Bay Rally the 3rd week of March. DO-ABLE! Then I can Tweak things at will.
WC

 

[capturedbyrobots]

DT,
Seems like it's you and me here pal. haha, and the guy that got swallowed by robots. AGAIN. hmmm. Mysteriously absent...
Anyway, trust me, I ran ALOT of numbers before I dove into this project. I re-checked and it was in fact a gear ratio calculator I downloaded from THIS site. It was published by one Jim Sitton. Sorry, I've got it on my machine but can't locate the link. However, I do NOT trust this guy's speed calculations. Especially now that I have and actual working model.
Anyway, using the calc. or even basic math, and if you believe the advertised gear ratio of 7:1 at low end, then with my 12/44 final drive, I would have a 25.6:1 on the low side. And assuming a 2:1 ratio at the high end ( I no-how believe these things can hit anywhere near 1:1 just from observing the belt at various rpms) , an equivalent 7.3:1 in full zip mode, I'm thinking those numbers work for a WIDE range of ratios. Since it seems everyone here is advocating an approximate 18-ish:1 for a single speed setup, I thought I would be in good shape. And in actual practice, seems I am. I'm really happy with the CVTs performance on the same engine over the friction drive (the only thing I can compare it to).
NOW, that's not to say I won't be playing with different ratios in the future. I may try a 10/44;12/56; or beyond but for now; I'm good. And the BETA portion of my system is over. I put on another 10 miles the last couple of days and it seems ready. So, now I'll be taking it apart and painting stuff and replacing the fender in the rear and working on the lighting.
All that will be killing me as I really have been into riding this beast finally. Yet I'm hoping to have it all back together for the next Tampa Bay Rally the 3rd week of March. DO-ABLE! Then I can Tweak things at will.
WC

I'm right here.....
Personally, I do believe that a larger rear sprocket can only help things,
though do you know what the max RPMs of you motor is?

I was going to stay away from bike chain for this,
because you just can't get the front sprocket small enough.
That's why I was going to stick with #35 or 219 chain, and
weld this style sprocket to the splined shaft 8mm sprocket, but grind off the 8mm teeth. The old sprocket would just act as a center sprocket coupler to the output shaft of the CVT.
(ignore the bearing in the picture, I would just pop it out and weld the whole sucker on the the splined original sprocket after grinding....)


http://estore.websitepros.com/768505/Detail.bok?no=986

 

[spad4me]

This is what I have used in the past welded onto the ground down c-ringed stub from the cvt

upgrade your Engine to the DAX Motor 1.5 mm
wide 081 engine sprocket counter shaft sprocket.
This 10 tooth engine sprocket allows you to run 415
chains and 081 BMX Bicycle chains for lighter
weight and more performance. Only $9.49

http://www.thatsdax.com/ENGINE_KIT_PARTS_PAGE_2.html



I think this will work even easier, not quite sure yet though.
PTO 10T DRIVE SPROCKET STEEL . FITS DAX
TITAN Gear Box PTO and others with 6 cog
spline. New Style one Piece milled. ONLY
He is out of stock at this time on these. So I can't test one. YET .



http://www.thatsdax.com/ENGINE_KIT_PARTS_PAGE_4.html


Thats dax also has up to 56 tooth rear rag mount sprockets.
CHEAP

 

[Large Filipino]

Okay I'm completely convinced that this is an absolute MUST DO!

I love that setup Nutsy. I got one of those 10 tooth gears it would have bolted right up. I'm gonna be using it for when I get mine.

I'm sure the 10 would help on the bottom end.

How's the drag with the fixed sprocket?

And is the 4 mounting bolts to the bell housing enough to keep things upright? Do you feel a need to support it better?

 

[Nuttsy]

LF,
There is definitely some drag. Ya don't want to be pedaling this thing very far although I did just to try it. You could make it home but you'll be bushed! The 4 mounting bolts would probably be enough but I went ahead and added another on the CVT. It just seems it makes the setup a little more stable when the torque is applied. Then again, it might just be in my mind but I'd rather err on the side of excess. And since the holes are already there, why not use them?
WC

 

[Nuttsy]

Captured,
I don't know all that much about chain drives but I don't think I'd go any smaller than the 35. These bikes can get heavy and it seems that the bigger chain might hold up better, especially with the length of run. And with a #35, what would you install for the rear sprocket and how. I guess how would depend on the bike and hub. Another reason I went with #41. Stay with the known quantity and all.
I like the idea of using the original sprocket as a backup plate. I wonder if it could be drilled instead of welded. That would allow for quick sprocket changes if need be. I tried drilling a rear bike sprocket once and no dice. I hit it with every type drill bit I could find and couldn't even scratch the hardened surface; literally! Yet, the sprocket I'm using is hardend too and I was able to drill and tap a set screw hole. The Dax sprocket Spad linked to would be nice too if the splines were the same size as the shaft. I came across so many in my early searches that had the splines but were not of the same diameter. RATS!
WC

 

[Nuttsy]

Captured,
Max RPM on the Robin 35 is 7000. Max torque is at 5000. Those are no-load numbers. That having been said, with the load of a heavy bike and ME, I'll never see 7000 and wondering if I'll hit 5K. Maybe, but I have no RPMeter to tell me these things. Just have to go by the sound of the engine. Maybe one of those little tachs would be a good investment for tuning and playing with gears and such.
Nickel and dime; nickel and dime!
WC

 

[capturedbyrobots]

Captured,
I don't know all that much about chain drives but I don't think I'd go any smaller than the 35. These bikes can get heavy and it seems that the bigger chain might hold up better, especially with the length of run. And with a #35, what would you install for the rear sprocket and how. I guess how would depend on the bike and hub. Another reason I went with #41. Stay with the known quantity and all.
I like the idea of using the original sprocket as a backup plate. I wonder if it could be drilled instead of welded. That would allow for quick sprocket changes if need be. I tried drilling a rear bike sprocket once and no dice. I hit it with every type drill bit I could find and couldn't even scratch the hardened surface; literally! Yet, the sprocket I'm using is hardend too and I was able to drill and tap a set screw hole. The Dax sprocket Spad linked to would be nice too if the splines were the same size as the shaft. I came across so many in my early searches that had the splines but were not of the same diameter. RATS!
WC

I am willing to bet that the 8mm sprocket can be drilled.
Welding would be much easier though.
The bottom sprocket could be attached best to a disc brake hub.
Mount a brake rotor on the hub, then drill holes in the disc rotor or sprocket
(most are aluminum so easy to drill) and bolt the sprocket on.

Just an FYI,
I run 25H chain on my CVT goped, and I have never broken a chain.
25H is small but strong.
I weigh 175, and the goped weighs about 45lbs.
35 and 219 chain is almost the same size, and is perfect for this application.