CVT LF's Buggy Bike got itself a CVT today!!

[Large Filipino]

Sure enough I have the 5 speed cluster on with the 15 tooth on the jack shaft and it's staying on 7 to 1 even with engine screaming. So maybe I'll put on the 12 tooth.
Is there any way to adjust these things? I rather like the gear it's on now because it has the pulling power.
I do notice like in the video above at no load it still takes a lot of RPM before the belt goes to top gear as if the spring is too stiff.

 

[Large Filipino]

Wait a minute loquin. I just read your post again. My daughter has my card reader so I can't upload this video I made today of what it's doing. Right now my gearing is comparable to Cronus gearing maybe a bit taller but this gearing did okay with the 5 to 1 gearbox.
It goes slow and it never builds up. So I should go even lower? Or should I go higher changing my jack shaft sprocket over from a 15 to a 12?
I'm also thinking my spring on the second pulley where it's visible may be too stiff. Any way to adjust this?

 

[Large Filipino]

This post deserves it's own thread. I figured out how to adjust these CVT's. Sorry my daughter still has my card reader so I can't yet transfer any pics.
On the secondary pulley where the exposed spring is,you can adjust the tension to the spring. I set mine as loose as it can go tonight. In the morning I'll see if the shifting improves.
I wish I can show a pic but essentially put a socket on the chrome nut over the spring then with a thin wrench turn the thin nut that's connected to the spring cup while holding the chrome nut with your socket wrench. Turning this thin nut clockwise tightens the spring making your CVT shift at a higher RPM and turning it counter clockwise makes your CVT shift at a lower rpm because spring tension is less.
Again I'll see in the morning how this changed anything. Originally I saw about 2 mm of thread then I turned the nut counter clockwise as much as it would go until it bottoms out and there's no threads visible.

 

[loquin]

The contra spring is there just to keep the driven pulley sheaves snug against the belt. I don't believe you want to be adjusting it much...

If the gearing is too tall then the CVT isn't going to ever be able to get out of the 7:1 low speed range.

The gearing for the top-end speed should be chosen based on the 3.2:1 gearbox on the output of the CVT, and NOT on the 7:1 total reduction at low speed.

So, if you want to go 25 MPH (max), and you've got a 26 inch wheel, the wheel needs to spin at 323 RPM. If the motor is running at 7000 RPM, the total reduction between motor and hub must be 21.6:1.

Since the CVT gearbox is at 3.2:1, the remaining reduction should be apx. 6.75:1

What are the tooth counts on the CVT sprocket, the jackshaft(in) sprocket, the jackshaft(out) sprocket, and the hub?

 

[Large Filipino]

Man the tinkering just never seems to stop. The 3 speed set up was rather okay except that I was slowly losing 2nd gear and my huge sprocket was slipping too much so naturally I have to find another way.
Well this go around I think I got it.
This CVT I rather have to get used to it because it loves rpm so I gotta keep the engine spinning.
But it's eerie because when you set the rpm's to get you going you just hold it right there to allow
the bike to catch up. It just accelerates while the engine stays at the rpm your throttle dictated
to it..yea.
So there was this slight downward slope I didn't video it and I gunned it. It still wanted more
I was absolutely flying it must have been close to 40 mph.
So to lessen the loads on this tranny I'm gonna do just one more mod and that's to change the 15 tooth on the jackshaft to a 16 tooth.
This go around there's far less stresses on the jackshaft sprocket from slipping because the wheel
has a larger sprocket than that tiny 19 tooth on the 3 speed. And that really makes a difference.
Here's my riding video from today.
Oh and that Bang Bang noise you hear when I slow down? That's my coaster hitting my bed in back.
It's rather fixable but seeing that's my only brake this trike is rather dangerous right now.
I really need to do a front brake.
And maybe a ram air... and route that exhaust... some paint maybe...

YouTube - First Ride Video Titan Front Wheel Drive Buggy Bike with CVT mod

 

[Large Filipino]

What are the tooth counts on the CVT sprocket, the jackshaft(in) sprocket, the jackshaft(out) sprocket, and the hub?

This is a 20 inch wheel so the sprocket on the wheel if I remember right is 28 tooth to the 10 tooth on the Jackshaft. Then it's 15 tooth on the end that the 10 tooth drives from the CVT.

I'm kinda funny with math stuff. I understand better how many times an engine turns for one revolution of the wheel.
For the 5 to 1 gearbox I always tried to go 5 gear box revs for one rev of the wheel.

So do you think a 16 from a 15 is okay? I have a 20 tooth and I already know that's too low.

Maybe a 17?

Many thanks in advance,btw.

And on that spring tension it was set down a bit needing a lot of rpm to make that belt go even at freewheel with no load. Adjusting it down made it shift up with less rpm.
It's not slipping but I'll keep a watch on it.

 

[loquin]

Currently, you have a total ratio of 13.44, motor to wheel

If you go to a 16t, the ratio would be 14.34, and for a 17t, 15.23.

at 7000 RPM, the top end with a 20 inch wheel is about 31 MPH.

With a 16T sprocket, that would drop to about 29 MPH, and for the 17T sprocket, it would be about 27 MPH

(the 20T sprocket would drop it down to about 23 MPH)

 

[loquin]

BTW. Were you using the 20T sprocket at the same time as the 19T sprocket at the wheel?

 

[Large Filipino]

Yep. The 3 speed got the 20T and that puppy had the 19 tooth sprocket at the wheel so you can see how that would strain the whole setup but with the 28 tooth at the wheel the strain is significantly less.
Also the 15 tooth has a 1/2 inch bore. The 20T has a 5/8 bore with a reducer. Aside from actually drilling a depression so you can screw into the axle I've done this and snapped my axle down the road that's how much strain it was getting there really was nothing much else to do aside from just welding the #$%^ thing on there but it would snap sooner or later.
But because the wheel sprocket is larger on that 5 speed cluster wheel currently on my bike then there's much less strain on the system so maybe I'll try that 20T on there again. 23 mph is acceptable because this is a load hauling trike I get my groceries on a daily basis and I really want to tackle that hill.
Then my other thoughts are the bigger the wheel sprocket the less strain on the jack shaft so I have an answer right here with a 36 tooth bolted to my original drum brake wheel but without that freewheel and I need to get this welded better at the local muffler shop.
In real world situations the only times I'm actually pedaling though and loving the freewheel is when I go to the flea market walking my trike with no drag is just sweet and it's a rolling shopping cart you wouldn't believe how much %$#^ you can fit back there.
Then there's that stretch of park when I shut it down and pedal in the park area when I'm gonna walk my dogs trapped in my cage.
Also a freewheel when you throttle down just keeps that trike rolling. That's always a good thing but down hills sometimes a fixed sprocket you can use engine braking.
I may just slip that drum brake wheel on this weekend after getting that sprocket welded I really want to keep that 15T sprocket on the jack shaft because any bigger in teeth numbers then the bore is 5/8 needing a reducer.
But what I think I'm gonna do is get with Gebee and buy a 44T freewheel sprocket to mount on a 20 inch BMX freewheel hub or get their hub that comes with their band brake and lace a rim on that puppy.
But it seems Gebee.... there's no way of buying directly from them.
Anyone know any distributors?
Thanks again loquin for those top speed numbers!

 

[loquin]

I agree about the freewheel. Staton sells a freewheel adapter in various bore sizes, for 12-15 bucks, btw. So you can mount a freewheel on a shaft. Then, although the rear sprocket/chain would still spin when coasting, the drag on a chain drive (only) is pretty minimal. (properly aligned, a chain drive can be up to 98% efficient.) With setup, you would use a standard freewheel on the output of the jackshaft, and a standard sprocket on the rear hub.

Here's Staton's standard freewheel adapters. He also has three-prong freewheel adapters. I'm not sure what the difference is with them...

• 15mm Adapter
• 5/8" Adapter
• 3/4" Adapter
• 7/8" Adapter
• 1" Adapter