Wow!

[robbie]

Never used a CVT before until now.... WOW!

I bought a couple of dead pocket bikes from a kid on craigslist. Used the wheels and brakes on a home built bike big enough for a normal human, along with a $19 CVT off ebay, which bolted right onto the standard-issue Chinese 49cc engine.

The bike has slick 10 inch tires and a 4 to 1 gear ratio after the CVT. The tires are not correct for gravel driveways, dirt roads and off-road riding on the farm, which is pretty much all that's available around here. But it really takes off, and accelerates to high speed. Well, it felt fast anyway, because I was sitting on a pillow (haven't built the seat yet) and trying not to wipe out. Realistically, I was probably going somewhere in the neighborhood of 15 mph, but it will go faster. I kept backing off the throttle because I didn't exactly feel safe. Not bad for a piece of crap I have less than $50 into. I think I'll put the finishing touches on it, paint it nice, and sell it to somebody who lives in town with lots of pavement. I'm already planning the next one, using the same powertrain!

 

[ctraugh]

Cool, could you post some pics, would like to see it.

 

[solomon]

Pics would be great! I love buying "broken" items off craigslist. I purchased a gokart for $100 Broken, and within 1 week (waiting on parts in the mail) it was fixed! I had only invest $15 (brakes) into the kart which i now believe I can sell for $300

 

[Raywelder]

where did you get a 19 dollar cvt??

 

[Raywelder]

You sure it wasnt just a gear reducer and not a cvt? all the Pocket bike Gear reducers on ebay are 19 but cvts are over 60. If you got a cvt at 19.00, I would be all over that.

 

[robbie]

Says CVT right on the side. $19 on ebay, no kidding.

 

[Ratbike]

Cvt?

Is that like a TAV from what used to be comet??

 

[robbie]

Yes, really, it's a CVT. That's why the subject line of this thread is "WOW". I had never used one before, and I had my doubts whether a dinky little 49cc engine would be able to get the job done. But it did. CVTs are amazing! I weigh 220 pounds, and the bike just took off! I don't think my kids will be riding this one. I'm going to build more bikes with bumpy tires.

Here's the link on ebay. You can thank me when you buy one, because I searched for 2 days for an affordable unit before I found this. I think he's moving a bunch of stuff out of his warehouse, so when these are gone, they're probably gone. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&Item=250606130844

Of course I already stocked up! I bought 4.

 

[robbie]

Here's some more info from recent experience. The output on this CVT is an 18 tooth 8mm sprocket with a splined hole. I used a 4:1 ratio and a 10 inch tire (or maybe it was 11). It doesn't peel out much, but it almost did a wheelie when I wasn't careful. If you need other sprockets, there are guys selling ones that will fit. Just search "8mm sprocket" on ebay and you'll come across sprockets with various numbers of teeth.

 

[robbie]

Ratbike: CVT is Continuously Variable Transmission. Same thing as the Comet Torqua-A-Verter, also known as a go-kart torque converter. The auto industry is more likely to call it a CVT.

 

[Russ2251]

Automotive CVT:

 

[robbie]

That's awesome. What kind of car is that?

By the way, requested photos have been posted in a new thread.

 

[Russ2251]

It's a Dutch car called a Daf. I believe they invented the CVT.

 

[Raywelder]

Aw man! thanks for the link, We were wanting one for a motorized bike we are building. (kickstart briggs)

 

[robbie]

They'll probably all be gone by this afternoon.

 

[robbie]

Aw man! thanks for the link, We were wanting one for a motorized bike we are building. (kickstart briggs)

I just saw that last part about the Briggs. The CVT in question bolts right on the standard issue 49 cc Chinese 2 stroke. I had to shim mine with one washer on each bolt to make it perfect. It comes with the clutch bell in place, to fit over the clutch pads on your engine. If you put it on a briggs, you'll have to make an adapter to attach the transmission housing to the engine, and you'll have to figure out how to attach the correct clutch pads to your crankshaft.

OR.... the input shaft on the CVT has a 5/16" male thread which the clutch bell screws onto. You could make an extension shaft that screws onto it and drive it from your engine via a belt or chain from a regular centrifugal clutch.

Either way is too much hassle for the condition my shop is in right now. I'd like to have some nice machining equipment in the future, but I still have to put the building up! I was going to adapt this CVT to a 2.5 hp Harbor Freight engine, but I decided to put a jackshaft reduction on that kart and use the CVT as intended with the 2 stroke instead. I'm glad I did it that way. It bolts right together. (and the kart with the 2.5 hp works great, too.)

 

[Raywelder]

Yea, It will definitely need adapting, I just wanted a cheap, small cvt, to adapt to it.

 

[robbie]

I'd love to see photos of it after you finish the modifications. It's not meant for a very big engine...

 

[SpyGuy]

Hey, Robbie, thought you'd be interested in seeing this:

Recognize the CVT? This is on a mini-minibike (28" long from outside edges of wheels), and the CVT provides plenty of torque for starting off. Top speed isn't great - like you said, maybe 15mph or so - but it pulls like a freight train .... (If you're interested in kowing, the entire bike is made from recycled metal - the frame and forks are tire irons and 1/4" plate, old wrenches make up the upper engine mount and tank mounts, and the wheels, exhaust pipe, and seat are from a wrecked goped.)

 

[robbie]

That is the most awesome thing I've ever seen! I love it. Especially the tire tools!

That doesn't look like a CVT, though. It's a simple gear reduction, isn't it? Go back to the link I posted above and BUY ONE! You have to try it. It would make a little bike like your scrap project go like crazy. Mine was going 15 or so, but that's because I had smooth tires on gravel and I kept backing off the throttle. I have a 1/4 mile long driveway with big rocks, curves and hills, which is totally not appropriate for the tires I was riding on. That thing really rips if you let it. On a smooth stretch I could swear I was going around 25.

Get the CVT. It's only $25 with shipping.