Snake Eater CVT

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bowljoman

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Aug 7, 2010
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Wa
I pondered the 410 sprocket and may try it one day. The only issue was finding a suitable 410 for the wheel, that would accept the freewheel and have the requisite number of teeth for my ratio. I could probably get Martin Sprocket to build one but that's lots of $$$$$$$.

It doesnt have to be 410, exactly. I reduced the rear wheel size, and I use a

16 tooth bmx freewheel.

10 inch rear scooter tire, and I get 42 mph.

here's my calc.

http://www.thebitstream.com/scoot/
 

corgi1

New Member
Aug 13, 2009
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i like that calculater,adjusted the gear sizes,guess the extras are for a shift kit,anyway ,mine went over 100 mph,that would be some bike ride
 

kerf

New Member
Jun 28, 2010
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Birmingham, Al
As long as I'm discussing modifications to the pocket bike CVT, I need to mention one other modification I've made. These tranny's are designed to run in a horizontal position, as the gearbox has a vent plug that should be directed up. In my application, the tranny is mounted in a vertical orientation, placing the vent plug down and that won't work. Our own Neat Times as well as the guys at GoPed Nation solved this issue by replacing the vent plug with a solid bolt and while their solution has worked, I felt it should be vented.

My first go at venting involved sweating a piece of brass tube into the hole in the vent plug and attaching a piece of clear tubing via a rubber elbow. This formed a oil reservoir for the oil to expand into and a way to check on the oil level. While it worked, I could never get the clear tube sealed to the rubber elbow and it leaked. My next try involved sweating a 1/8" pipe x 1/8" hose fitting into the vent plug and using an 1/8" pipe elbow and a 5" x 1/8" pipe nipple to act as the reservoir. This didn't leak but required a dipstick to check the oil level. I soldered a piece of brazing rod into a vented brass cap to make the cap / dipstick.

Filling the gear box needs to be done before mounting, with the tranny in a horizontal position. The fill plug on the low side of the gear box is removed and oil is forced in until it comes out of the reservoir on the high side. Any trapped air will be "whipped" into the oil which is forced into the reservoir when the tranny heats up. The air will separate from the oil and be vented away. After several of these heat / cooling cycles, all the air will be expelled, leaving a gearbox completely oil filled.

This project has taken a lot of work by trial and error but the results, IMO, are worth the effort. I would pretty much put my bike up against a factory moped and I feel I could hold my own.
 

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wayne z

Active Member
Dec 5, 2010
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louisiana
Thanks Kerf and others, I learned a LOTof good tips and tecniques following your thread.

You have definatly changed that cvt from a stone to a jewel.

When my Hoot chainbox gives out, I'm gonna try one of those on my HS.

Just have to mount engine with pullstart on left side and move pedal chaining to that side too.
 

NEAT TIMES

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May 28, 2008
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Wayne z

my original plan was to also move pedal chain to left side. Then i came up with the double freewheel on the right side. It has worked out very well. Much easier. Thinking it is `cvt rack mount` thread.

Good luck, ron .cvlt1 cvlt1
 

kerf

New Member
Jun 28, 2010
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Birmingham, Al
Thanks Neat, I realy like that idea,gonna try to find that thread
The link to Neat Times thread is located in post #1 of this thread. His solution, putting both drives on the right side, was a stroke of genius. If I hadn't already had an expensive Staton wheel, I would have used his setup.
 

wayne z

Active Member
Dec 5, 2010
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louisiana
The link to Neat Times thread is located in post #1 of this thread. His solution, putting both drives on the right side, was a stroke of genius. If I hadn't already had an expensive Staton wheel, I would have used his setup.
Ok, i found the post. What is a Bb kit? Who sells them?

This should be esaier to do on my bike,using a single speed pedal chaining.

Thanks, Wayne
 
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NEAT TIMES

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May 28, 2008
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Wayne

bb is for bottom bracket = where the pedals are mounted. All the info should be in the thread. The part # , price and seller. The bb kit is a set of bearings and the threaded cups. The cup with the right hand external threads is used to join the freewheel bearings together.

If you study the post`s in the thread you should be able to understand. The rear derailer is just used as a chain tensenior as you only have one rear sprocket for the pedal chain. When you purchase the rear pedal sprocket get a 3/16" wide teeth sprocket or go to a bmx chain for the 1/8" wide teeth sprocket.

Also, if you mount the large motor driven sprocket on the inside of freewheel flange (spoke side) you should be able to omit the spacer between the free wheel bearings. The free wheel hub`s are hardened steel and tuff.

Ron .cvlt1
 
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kerf

New Member
Jun 28, 2010
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Birmingham, Al
I've managed a few test rides since completing my modifications and I've been itching for a twenty miler. The weather has been bad, with all the ice but it's gotten above freezing a couple of days and it's been melting. I am all fueled and charged up for a 5AM run to the Norfolk Southern train yard at Irondale, NWS said the low would be 33, sounded like a go. Got up and my thermometer read 30 degrees, lots of water out there from melting ice, I chickened out. Figured if I hit one patch of black ice, my day will go down hill quick.

Don't know if I've become smarter with age or just a coward.

PS
Some pictures from last weeks ice storm.

http://motorbicycling.com/f28/welcome-deep-south-26514.html
 
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kerf

New Member
Jun 28, 2010
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Birmingham, Al
It's been three weeks since my last ride and subsequent modifications. The weather has been pretty uncooperative but today things were better. At 5:00 AM the temp was a balmy 48 degrees and it was dry, sure beets the 28-30 degrees last time. Even with the warmer temps, I still managed to screw up and go under dressed, wearing a sweat shirt instead of my coat. About froze my bum off!

I may have been uncomfortable but the bike was at the top of its game. A good hard 20 mile run, with plenty of hills and she worked just like any factory moped. Other than running over a center divider while making a left hand turn, the ride was uneventful with never a pedal turned. My modifications seem to be a success. One thing I have noticed about the CVT is my mileage has gone way down. I guess the drag in the belt drive may be responsible but it is a small trade off for a fully automatic transmission.

Kerf happy!!!!
 

4950cycle

New Member
Sep 8, 2010
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Dunnellon,FL.
I know what you mean about the weather here in the S.E. . I live in north central FL. and just lately been getten some decent riding days. It's been a lot of the same temps as you in upper AL. Kerf.
 

kerf

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Jun 28, 2010
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Birmingham, Al
I know what you mean about the weather here in the S.E. . I live in north central FL. and just lately been getten some decent riding days. It's been a lot of the same temps as you in upper AL. Kerf.
I just got back from a 20 mile run to the train yard, saw a west bound intermodal and another freight leaving Norris Yard. It was 59 deg. when I left, still in thermals, jacket and gloves but comfortable.

The CVT, even with the issues, I'm afraid has ruined me forever. The bike handles just like a factory moped, pulls off from a start, even up hill w/o pedaling. I cruise at 30 with no strain, when you hit a hill, the bike slows down to about 20 but the engine doesn't bog and there's no shifting. Think I'm going to pull the belt cover today, just to check things out and make every thing is like I left them.
 

curtisfox

Well-Known Member
Dec 29, 2008
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You mean its working like it supose to? Keep us posted I have two and will redo them before I use them. I was very disapointed when I took mine apart and seen the shafts and clutch drum wable. But will redrill and put the new threads on.

I know the Comet ones work great and are used on Jr.dragsters and all and don't see why they can't be made to work the same.

Its just a shame that one has to go through all that work.........Curt
 

kerf

New Member
Jun 28, 2010
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Birmingham, Al
Since my CVT overhaul, the first week of January, I guess I've only ridden about 120 - 140 miles with the weather as it has been. After my 20 mile ride this morning, I did a little exploratory surgery to see how everything was holding up. I pulled the belt cover and removed the nut and washers from the variator shaft, here's what I found:

Outer variator sheave was still tight on the shaft with no signs of shaft wallowing.

There was very little if any belt dust in the cover, belt looked good.

There were no signs of gear oil leakage anywhere.

The engine was 4 stroking in the low to midrange, plug was black so I'm going to lean out the low speed circuit.

I took two coils off the spring on my chain tensioner to tighten the drive chain a little.

That's about it, no drama, no fuss, no mess.
 

curtisfox

Well-Known Member
Dec 29, 2008
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minesota
AMEN! Time will tell keep us posted. Thanks for all your hard work and posting all the info. I will give it a try this sumer and see what happens.............Curt
 
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kerf

New Member
Jun 28, 2010
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Birmingham, Al
Just thought I would update the CVT project. After I destroyed and patched up my first tranny, I decided it was time to go again and do it right this time. The areas of concern with the original CVT were the clutch shaft bearings, the variator back plate stop, the outer variator plate reinforcement and the gear box seals.

I bought a new tranny and began to replace and rework parts before going into service this time. After the mods, we're back on the road again and things are much better. With the new tranny the gas mileage has increased, a 30 mph cruise speed is almost too easy (6750 rpm out of an 11,000 red line) and the pull off from a dead start is as good as any moped on the market. I got to quit riding this thing with the engine running because I don't pedal anymore and I'm getting out of shape bad.

Signed,
Happy But Fat