New vari speed tranny build

[wayne z]

Gettin way close! OK I was wrong about the machcine work being the hard part. At least doing that, everything is calculated and tou know what the results are going to be.

All this linkage, idlers ,and plumbing to figure out is definitly uncharted territory.

All that's left now is the throttle linkage and fuel system. Good chance I'll get a test ride tomorrow.

 

[silverbear]

That sure is a good lookin' machine. Is that exhaust manifold something you made up? The pipe looks good!
SB

 

[Sidewinder Jerry]

I put a Staton crank drive on my Land Rider auto shift bike. I manually shift the front three gears and the rear seven shift automatically. I live in Oak Ridge, TN we have lots of steep hills and long grades.

 

[lanternman]

Hi, love the build,I would like to know where you got the wheel pulley. I am working on a new build and trying what to do. Lanternman

 

[wayne z]

Yeah I fabbed the exhaust today. I brased a modified 3/4" street ell to the original flange. By modified, I mean I just drilled the male side of the street ell to match the port on the head, and cut off the threaded part to shorten it's height to make the 90 just clear the exhaust studs.
Then I chucked up a short piece of threaded pipe nipple, and bored it for an interference fit with 3/4 conduit.
Then I bent the conduit to fit, and used a plastic mallet to drive the nipple onto the conduit and screwed on the ell with flange, before mounting.

 

[wayne z]

Hi, love the build,I would like to know where you got the wheel pulley. I am working on a new build and trying what to do. Lanternman

I bought it off Ebay. Just do a search for wizzer parts.

 

[curtisfox]

You can also get them from:
Simpson Motor Bikes
They were $39 last I looked......................Curt

 

[wayne z]

Well, I got it on the road today. Works pretty good. Verysmooth andquiet drivetrain. Shifts from low to high and back easily with the handlever. There is some belt slipping at the varipully though.
The spring tension of this pully is prolly designed for fractional hp motors. So I had to feather the throttle a good bit with the torquey lil Preddy, sorta feels like the slipping of a fricton drive, where you have to roll the throttle on slowly to keep it from slipping. The belt isn't very tight no matter where the pully is.
Gonna look into swapping out the spring for a stiffer one. Or maybe using a larger pully designed for a more powerful motor.

Now I see why the MTD mower drive uses 2 varipullys on a spring loaded pivoting jackshaft, to allow pully movement, and keep high and equal tension on both belts.

Another option is to figure our a way to use the pully in the primary drive, where torque is about half of what it is at the secondary drive.



Now I can clean up the mess I made of the workbench doing this build LOL

 

[vintagebiker]

Very nice work.
Hope you can solve the slipping with a stiffer spring.
I was wondering, how much resistance is felt when you pedal the bike with the engine off?

 

[wayne z]

Very nice work.
Hope you can solve the slipping with a stiffer spring.
I was wondering, how much resistance is felt when you pedal the bike with the engine off?

It has about the same or slightly more resistance to pedal as a Happytime motor.
If I can't solve the varipully problem, I'll just use a standard pully, and still have a great drive train.
Or, I could build it into another 2 speed with belt drive secondary.

 

[wayne z]

OK, I tightened down the idler to get no slippage and keep it in low range(@14:1) and tested it.
This is one sweet, quiet Preddy, can't hear any valve train noise like my first one.

Strong!. I stopped dead on a 24% hill, and without pedaling, took off and made 10 mph before cresting the short hill. Hit it running, 20mph no sweat at all. Accellerates quickly from dead stop to about 26 mph at about 5500 This is perfect gearing for city traffic.
The little 3" comet clutch locks up pretty quickly at about 10 mph. . If you stand beside the bike, hold the bars and goose it, it will stand straight up! I think that if I put the front tire against something, I can make it smoke the tire.

This thing runs great. If I can't sort out the varipully issue, I will just put a manual adj pully on there and adjust it for when I'm home in the country, or at work/play in the city.
Later this weekend, I'm gonna put on a solid pully for 9.75:1 ratio and see what it does.

 

[silverbear]

Woohoo!
SB

 

[curtisfox]

The double vari-drive on a lawnmower have a spring loaded idler and a spring on the pivet to hold it tight. Maybe something like that to keep the slap out?........Curt

 

[cannonball2]

Wayne, the adjustable pulley works well if you have to go that route. When I ran mine I carried the allen wrench stuck on magnet under the frame. Adjustment was quick and easy, just not on the fly.

 

[wayne z]

OK, I installed a fixed 3" pully on the jackshaft output, for a 10:1 total ratio. All I can say is that this thing rocks!
The comet clutch likes to lock up early, and the Preddy is torquey enough to power away from a dead stop quickly and easily,up to about 38 mph at my self imposed 5000 rpm.
Don't realy seem to need a low gear.
The all belt drive is very quiet and smooth.

I can put the front wheel against a post and open the throttle, and easily smoke the rear tire on blacktop without any help other than twisting the throttle.
I did have to add a top and foreward engine mount, to stabilise some unwanted movement of the lower clamp on engine mount. Also came up with a nice exhaust shield.

 

[motorhedfred]

So are you done experimenting with the vari-speed setup Wayne ?

 

[wayne z]

No, I'm gonna take the pully apart tomorrow to see about installing a stronger spring. Had to get some snap ring pliers for dis assembly. got some motorcycle springs ect to try to retrofit or whatever it takes to get a lot more tension that it has now. then i think it will work great.
I have a fixed 10:1 ratio pully on it now, and I am very happy with it's single speed performance. tops out way past 40. The 99cc Preddy has enough torque to take off quite briskly with a single speed centrifugal clutch drive train.
Still would be much better and less wear and tear on components with some gears though, so i'm still persuing my vari speed idea.

 

[motorhedfred]

Good.

Even if you don't need or want it for this build, it might be just the thing for engines with less torque/horsepower. Someone might thank you later for all your research and breakthroughs.

MHF

 

[curtisfox]

Another thought is lawn mowers have guide pins to hold the belts from moveing to far or off the pullys...........Curt

 

[wayne z]

OK guys, an update on the vari tranny experiment. It finaly came to me yesterday. I have figured out an easy way to modify my spring loaded vari pully to add a much longer, stronger and adjustable spring.
At first, I was trying to get a much stronger spring in the little housing of the pully. Nearly impossible to scrounge a spring to fit with the tight and short space clearance in there.
Just gonna use a longer shaft sticking out of the back of the pully some with a shaft collar and a stepped washer to retain the longer spring. And I can easily fit springs of various dia. and length to tune this thing.
Mt first spring to try is gonna be from a bike shock. Anybody got any advise for dis-assembling a shock absorber before I go out there and get on it?
Stay tuned :~)