Weed Wacker Revisited.

When you are running an engine around 30cc particularly of weedeater orgin a one inch is about the maximum unless you are truly in the flats. The calculator shows 20mph@ 7000rpm with the 1", so crusing around 15 should be fairly easy, If you want a "power roller" for load carrying try a 7/8. I have 2 rollers for my Mongoose work horse. a 1.875 for trailer towing and a 2.125 for traveling I find myself crusing along aroud 18 looking at stuff, a really pleasant speed. The Schwinn on the other hand will show a top of 38mph and cruise around 30. Its fun but not nearly as relaxing as easing along on the Mongoose.
 
I really am going to have to measure the 3/4 ID pipe nipple with a micrometer. I have one I have just enver bothered. It is probably closer to 7/8 than an inch. I find that the bike seems to do a little better but who knows.

With the 1.5 inch roller I found it almost impossible to relax. The bike seemed to be running "harsh" if that makes any sense.
 
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When you get too big of a roller, the engine is under constant or semi constant high load. I tried the Schwinn with a very large roller, just under 3" man did it have top end but in the real world of hills around here it was under constant high output which is probably what you are describibg as "harsh". I know its hard to loose top end once you have it, but unloading the engine makes for a nicer overall ride. Cool thing about FD, just make another roller, dont have to fool with sprockets or pulleys(probably catch it for that comment).
 
Not from me... It's why I stop building everything else. One thing always led to ten more things. Friction drive is bad enough, but someday someone will see the value in makeing a much more simple kit than those on ebay and with the dealers now. Just a motor with a roller on the shaft and a scissors henge with a spring between the two arms for tension. Bolt it on and ride away.
 
I was just reading a post about pvc and realized that I once had an idea and never followed through with it
I think that you could buy a few pvc water pipe bits and pieces for under a 2 dollars and make a plastic drive which would be easy to assemble and would go on the weed whacker bike easily.

Okay see if this plays for you. first you need an end cap for a 3/4ID pvc pipe. You drill a 3/8" hole as close to dead center as possible. Then you bolt that onto the flywheel..

Next you cut a piece of 3/4"ID pipe about an inch long and glue it into the end cap.

The you get one of those pvc pipe joints used to connect to pipes butt end. It is about 2 inches long. That you glue over the pipe sticking out of the end cap. At this point you should have a Pvc assembly sticking out about two or more inches from the flywheel. If it isn't long enough just glue and end cap onto the assembly.

My only question is durability of the plastic. I think I tried a pvc cover on a roller once and it wore out very quickly. this would not be easy to interchange. I like the idea because the engine would be turning something lighter than the steel I use now. And this stuff is self squaring, so easy to deal with.
 
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yeah I think it wears down way too fast anyway. Getting it on and off would be a pain if it only went twenty miles.
 
Deacon, if you were to make a bracket of metal to accept pvc pipe that bolted onto a WW, do you think you could build a strong enough frame to hold the motor... for a while?
I suppose schedule 80 might be better? It's commonly available.

A 3/4 pipe roller might be best of the commonly available things.
...been too busy with other situations to even make the motor bracket for my forked FD bike. Gotta get it going!
rc
 
I think i have about the easiest frame and driver combination now for a friction drive. Im just always curious. You know it's like the wheel hub connector there is always something better out there. The forks led to the angle iron rails hooked directly to the hub which cut down a huge amount of the vibrations when I used a hinge as a connector.

If you can keep the vibrations down, and you can keep the motor from hanging off the wheel and being supported by the drive roller rather than the frame, then these things might have a pretty good life cycle.
 
That weed whacker I bought first, that I never could make work has served as experiment central. Today I removed the back plug from the rear of the motor behind the flywheel. When I got it off, I tapped the holes for quarter inch threads. Most of the problems I have had with weekeater motors is vibrartion problems. I am thinking I might be able to strip down a motor and beef it up with bigger bolts and lock washers to hold it together a little longer.
 
Well im puttering right now. Trying things on that motor that doesnt work.

I have retreaded the motor I'm using so that the mount is held in place by quarter inch bolts with lock washers and flat washers to give it more contact area with the hanging mount. So the motor I am using has much less vibration than it did before.

So there is a cover for the back of the area where the piston rod connects to the drive shaft. It has those allen wrench bolts. I just rethreaded it to see if I could. If I come across another one of these, and Im sure i will its the homelite ryobi, I will probably rethread the whole thing to keep the vibration damage to a pure minimum.

I can remember when I did this before the motor mount broke on about half the motors i worked with. Most likely that's why I stopped using them. Since I retreaded the holes around the flywheel They don't get loose from the vibration so the damage has to be less.

By the way i rode the bike five continuous miles in traffic today. I am pretty sure that the heating issue would come into play after anything I will be using the bike for. It's only about three miles one way to anyplace I might reasonably expect to ride it.

It seems to me that even though I have removed cases before, vibration not heat killed the motors. Probably before the heat had a chance to do it. So basically I'm trying to eliminate as much of the vibration as possible. I wonder if a piece of inner tube between the between the motor mount and the frame mount would help.
 
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OK I get it now. When they build those things they use self threading hardware, figuring the unit probably will never be dismantled. Rethreading would sure be an improvement, particularly if the bolts are going to be used in mounting.
 
Since today I threw my drive shaft across the road while riding the bike, please be more careful than I was about having a balanced drive wheel. I guess it vibrated until it just broke off. I have broken more than one drive shaft. the frame of these motors is cheap pot metal so they won't take much vibration there either. The drive shaft at 5/16 is just too weak to stand much vibration.

I had a craftsman blower on hand with a 3/8 drive shaft and it is long so I can pressure mount the drive wheel. It should be more balanced since Im not doing any welding at all on it. the pressure of the nut on the end should hold the drive wheel in place. If not then I get to buy the big engine I have decided I need to do a out of town ride.
 
Actually that is a good idea. What do i get to make the laminates from, it has to be about three inches when it is layered together.
 
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I had a chance to inspect the ryobi engine more closely and I didn't twist the drive shaft off the spindle came apart. So its all good after all. Just have to redo it.
 
deacon said:
Actually that is a good idea. What do i get to make the laminates from, it has to be about three inches when it is layered together.
Click to expand...

The rubber mat I use is about 5/8 thick. You only need the rubber over the tire, you can use wood spacers to cut down on the rubber, or use all rubber. If you want a 1" roller cut it with a 1 1/8 hole saw, the drill the center with a 3/8 and you are in business.
 
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