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

[Logan1]

Here'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.

 

[michael whiteman]

After spending a year building something similar on an OCC frame I'll tell ya how truly impressed I am looking at your ride. I started with a single front brake, although mine was hydraulic with a 203mm disc. It sure had a lot of stopping power. Maybe that is the upgrade you'll end up with. My frame had the stock brake posts for the original rear rim brakes and I ended up installing them which did make quite a bit of improvement. I don't see any posts on your frame so rear brakes will be a major design thing for sure. It's a real hassle with fat tires like ours to get the proper clearance on the cables, arms etc. I considered a CVT but shyed away from one because of the expense. I'm impressed that you took the time to couple one to a 142F. I had that same engine on my old rat bike. Very dependable. That CVT gives you a 3:1 ratio and I bet your bike could climb straight up a wall with that big sprocket in the rear. The only way my clutch works now is to run a 1500 RPM spring with my 79cc Predator, and it still chatters a bit when taking off. I know what you mean about dealing with a CC. With your CVT you could definitely get away with a smaller wheel sprocket and pick up some speed without losing much noticable torque. Keep us all posted on your progress this summer. I love this speed calculator. It's so easy to use.

Motor and Gear Ratio Guide and Calculator for Vehicles with a Jackshaft - ElectricScooterParts.com

Electric scooter with jackshaft motor and gear ratio guide with gear ratio calculator.

electricscooterparts.com

 

[Sidewinder Jerry]

What size is the rear wheel; the tooth count on the drive sprocket and rear sprocket? Do you have hills to contend with? Since you aren't using pedals; I've got a setup in mind that'll get you the reduction you're going to need.

 

[cloakedvillain]

A jackshaft would go a long way to upping that top speed. your engine has got good torque but it once the variator starts variating. You're likely losing the torque it needs to go.

 

[Sidewinder Jerry]

A jackshaft would go a long way to upping that top speed. your engine has got good torque but it once the variator starts variating. You're likely losing the torque it needs to go.

Since he isn't going to be using pedals I'm thinking a jackshaft to the right side to drive a 3 speed rear wheel hub. I've calculated up what sprockets would be needed. Then the left side of the rear wheel would be free to attach a rotor for a rear disc brake. It'll be able to climb any hill and top out at 30 mph on level ground. Taking off from a dead stop would be no problem.

 

[Logan1]

What size is the rear wheel; the tooth count on the drive sprocket and rear sprocket? Do you have hills to contend with? Since you aren't using pedals; I've got a setup in mind that'll get you the reduction you're going to need.

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.

 

[Logan1]

Since he isn't going to be using pedals I'm thinking a jackshaft to the right side to drive a 3 speed rear wheel hub. I've calculated up what sprockets would be needed. Then the left side of the rear wheel would be free to attach a rotor for a rear disc brake. It'll be able to climb any hill and top out at 30 mph on level ground. Taking off from a dead stop would be no problem.

I'm not going to add a jackshaft, there's not enough space on this bike.

 

[Sidewinder Jerry]

I'm not going to add a jackshaft, there's not enough space on this bike.

Is it fairly flat where you're at?

 

[Logan1]

After spending a year building something similar on an OCC frame I'll tell ya how truly impressed I am looking at your ride. I started with a single front brake, although mine was hydraulic with a 203mm disc. It sure had a lot of stopping power. Maybe that is the upgrade you'll end up with. My frame had the stock brake posts for the original rear rim brakes and I ended up installing them which did make quite a bit of improvement. I don't see any posts on your frame so rear brakes will be a major design thing for sure. It's a real hassle with fat tires like ours to get the proper clearance on the cables, arms etc. I considered a CVT but shyed away from one because of the expense. I'm impressed that you took the time to couple one to a 142F. I had that same engine on my old rat bike. Very dependable. That CVT gives you a 3:1 ratio and I bet your bike could climb straight up a wall with that big sprocket in the rear. The only way my clutch works now is to run a 1500 RPM spring with my 79cc Predator, and it still chatters a bit when taking off. I know what you mean about dealing with a CC. With your CVT you could definitely get away with a smaller wheel sprocket and pick up some speed without losing much noticable torque. Keep us all posted on your progress this summer. I love this speed calculator. It's so easy to use.

Motor and Gear Ratio Guide and Calculator for Vehicles with a Jackshaft - ElectricScooterParts.com

Electric scooter with jackshaft motor and gear ratio guide with gear ratio calculator.

electricscooterparts.com

The hydraulic brake is a great idea especially if I decide to not add a rear brake. I think a smaller wheel sprocket is in my future as well.

 

[Logan1]

Is it fairly flat where you're at?

My current town has some hills, but I am moving to an area with larger hills.