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

[Logan1]

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.

I don't have enough space on this bike for a jackshaft.

 

[Sidewinder Jerry]

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.

With the engine you have you're going to need a minimum of an 18:1 reduction. Otherwise your engine will be doing good to get over 4500 rpm. Worse yet if you have hills to deal with. Burn out clutches are going to happen a lot as well since you aren't using pedals to assist with.

My shifter bike the Sidewinder

I have a creative way to put a jackshaft on your bike. It'd involve putting it over the rear wheel.

 

[Sidewinder Jerry]

My idea is to mount this gearbox over the rear wheel to be used as a jackshaft.

Staton Inc

2 to 1 Gear reduction box with idler gear so the input and output 5/8" shaft with 3/16" keyway turns the same direction. We made a new 5/8" shaft with a 3/16" keyway so it is easier to use standard made sprockets and adaptors. Note: We also have a 18 mm shaft version Product ID: 0087Use your...

www.staton-inc.com

This may even be a better choice since it's a 22:1 reduction you could keep all your sprockets the same size. You'd have to fabricate a cover to seal it up to contain the grease needed for it.

Pardon Our Interruption...

 

[Logan1]

That's not really the look that I am going for, thanks but I already know what I want to do.

 

[Sidewinder Jerry]

That's not really the look that I am going for, thanks but I already know what I want to do.

If you can fabricate looks can be altered to look good. I'm very familiar with the engine you're using and know what's required for them reduction wise. The reduction range on my bike the Sidewinder is 66.79\1~16.25\1. I live in the mountains where 30% grade hills are common. The engine you're using has 1.6 hp at 6800 rpm; 1.48 ft/lbs of torque at 4500 rpm; it idles at 2800 rpm; the clutch should engage around 3500~4000 rpm; 7500 rpm is it's safe maximum. Your CVT stock springs go from 3\1~1\1 at 3600 rpm.

On my shifter bike if I'm doing max hp rpm at 7000 rpm using full throttle shifting to a higher gear won't make me go any faster. The additional load on the engine will cause the rpm to drop and even slow me down some because I'll no longer be at max hp rpm.

We're all born ignorant

Foolish people never learn from their mistakes

Smart people learn from their mistakes

The truly wise learn from the mistakes of others

Before I had the Sidewinder I rode the LandRider which shifted 7 engine/human driven gears automatically. If you don't want gears you're going to need a more powerful engine.

 

[cloakedvillain]

It sounds like its working out for you. Its a shame there's no market for the x2 style cvts anymore. The tav2 and clones are built for small wheels and low rpm.

 

[michael whiteman]

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

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.

 

[michael whiteman]

There's not much you can do to improve that funky 142F engine. I replaced the stock muffler with a straight through glass pack which helped a little. I also found a carb with an idle mixture screw and drilled out the main jet a couple thou. No one considers making any HP upgrades on an engine that has only one plastic cam lobe for both valves. It's magic that even works at all. The real solution would be to stick a little Predator in there.

 

[LewieBike]

For those with sub 49 cc engines, here's a compact little gear box that could be adapted with a autoclutch bell housing for the Honda GX series with the 78 mm size clutch bells.

Pardon Our Interruption...

 

[LewieBike]

There's not much you can do to improve that funky 142F engine. I replaced the stock muffler with a straight through glass pack which helped a little. I also found a carb with an idle mixture screw and drilled out the main jet a couple thou. No one considers making any HP upgrades on an engine that has only one plastic cam lobe for both valves. It's magic that even works at all. The real solution would be to stick a little Predator in there.

Funny you mentioned the single lobed cam in the 142F, Ryobi's little 25 cc 4 stroke weed trimmer engine had a fully metal cam with the same cam actuation. This isn't really a new idea, as I used to own an old sidevalve Lawson 4 stroke pump engine, that had the same single lobed cam with followers.

Honda also made a few million of their CG125/150/200's pizza delivery bikes and the even more numerous Lifan CG engine clone motorcycles for developing countries with this same cam arrangement. It's remarkably tolerant of being revved up to 8K without valve float.