CVT West Coast Chopper 49cc 4 stroke with a Continuously Variable Transmission

[Sidewinder Jerry]

My advise Logan would be to not change anyhing until you move and find out what the new hills are all about. Maybe just concentrate on the brakes for now. You'll always need them. LOL

I have a pretty steep hill near by that I use for testing. My former rat bike with a 142F engine had an overall ratio of 22:1 and would accellerate all the way to the top. My current OCC bike with a 79cc Predator has a 12:1 ratio and slows down as it nears the top. The Predator has twice the power, but it's like driving a car up that hill in hi gear. The advantage you have with your CVT is, as it slows down the hill climbing ratio becomes better. Crazy huh? You still must keep that engine running at the RPM that makes the most torque. Your problem is that the 142F doesn't make a whole lot of power. So, by using that calculator you'll need to find a compromise between hill climbing torque and top speed on the flat.

The ratio in the CVT 30 series will lower if stronger springs have been put in them. Otherwise the engine will have to drop below 2300 rpm before the ratio starts lowering. The 142 idles best at 2800 rpm. Max torque is at 4500 rpm

 

[michael whiteman]

You are absolutely right Jerry. There is a lot of research that must be done before designing a drive train for one of these unusual bikes. Out of the box china girls, not so much. Most people don't have the answers, but moreso which questions to even ask. I am so thankful that our members, like you, have all shared their experiences and data. You can sure throw a lot of money at it and end up with pieces that did not perform to your expectation. Ask me how I know.

 

[Hoverbike Pilot]

View attachment 230566Here's the current iteration of my 49cc motorcycle project I've been working on for the past couple years. Originally it was a bicycle with pedals but I've mounted an engine, attached a custom rear sprocket, custom front wheel with a disk brake, and new paint job.

The bike ran great for a while however the clutch started having issues. I decided to convert the transmission to a belt driven setup which enables me to start from a stop without over stressing the engine. The transmission kit I used was not designed for my engine so I had to machine my own mounting holes and weld a custom shaft to mount the pulleys to. The result is a much more reliable system and a lesser top speed of 20 mph.

The single front brake is sketchy at best so I'm glad I have a low top speed; a rear brake is definitely next. I want to ride it around how it currently is for a while; I mean, the engine isn't even broken in yet. After upgrading the brakes, I'd like to look into upgrading the carburetor. I'd likely want guidance on that when the time comes.

Wow, I really dig this clean build. This was a very good read you shared on your build. Thank you!

 

[Sidewinder Jerry]

You are absolutely right Jerry. There is a lot of research that must be done before designing a drive train for one of these unusual bikes. Out of the box china girls, not so much. Most people don't have the answers, but moreso which questions to even ask. I am so thankful that our members, like you, have all shared their experiences and data. You can sure throw a lot of money at it and end up with pieces that did not perform to your expectation. Ask me how I know.

I discovered this with the LandRider. The auto shift derailleur would put the bike in its top gear around 15 mph. So I put a stronger spring in the cadence adjuster. That way it didn't shift into the top gear until around 25 mph.

 

[cloakedvillain]

Packaging is what it is. No real improvements to be made. Tune the cvt for high revs, throw a big momma of a sprocket on and enjoy.

The rear wheel is 20". The drive sprocket is a 12 tooth and I believe the rear sprocket is 48 or 52 tooth, it's been a few years. It goes up hills though at a slower pace.

There are 60 tooth sprockets available. You could get a moped hub. https://www.treatland.tv/new-REAR-s...iZWTK1SR-tGEaISge0lttQUsIgcRa_WEfe1rrLJQ9qwYg

Lots of options. .

 

[LewieBike]

The ratio in the CVT 30 series will lower if stronger springs have been put in them. Otherwise the engine will have to drop below 2300 rpm before the ratio starts lowering. The 142 idles best at 2800 rpm. Max torque is at 4500 rpm

The little Honda GX 31cc engines pump an oil mist around to their various lube requiring parts, I was lucky to discover a small engine forum post saying you should not lower the Honda GX pushrod engine below 2900~3200 rpm as the oil mist will not get circulated at idle speed lower than 2900 rpm.

 

[cloakedvillain]

What about the horizontal gx 50? That's what the huaaheng is copying.

 

[LewieBike]

What about the horizontal gx 50? That's what the huaaheng is copying.

If I am not mistaken they have a dipper on the connecting rod, like older, side valve, horizontal crankshaft Briggs. I'd assume they're fine at 2400 rpm give or take a couple hundred. Did you know that the early Honda 50cc motorcycle engine had an oil scooper on the connecting rod's big end? They also had a little oil feed to the OHV rocker arms, that was powered off the end of the camshaft.

These little engines made about 4.3 h.p. at 9000 rpm and they had pushrods.

 

[michael whiteman]

What about the horizontal gx 50? That's what the huaaheng is copying.

The 142f Huasheng has a single lobe plastic camshaft. I'm sure the Honda is a real engine. The similarity is the
49-50cc size.

 

[Will'smotobikes19]

What about the horizontal gx 50? That's what the huaaheng is copying.

The GXH-50 you mean. I had a gx50 clone its more of a trimmer engine than a stationary pump engine.