'77 Schwinn 2.5hp Home Made Friction Drive

Psycledeliac

New Member
Oct 16, 2011
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Flint Michigan USA
Hello.

I will be documenting the progress of my project here, hope someone finds it interesting.

I have a 1977 Schwinn Caliente and a 1978 Toro Snowmaster20 snowblower, basic tools, and almost no budget.




So, I suppose step one is to get that lil' motor outta that ol' Toro!
 

Psycledeliac

New Member
Oct 16, 2011
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Flint Michigan USA
Pulling the motor out was fairly easy, just undid every bolt in sight and it pretty much fell apart. This is gonna be easy! lol




Google tells me this is a Tecumseh 2.5 hp 85cc two-stroke engine. There's like a bazillion of 'em out there and they are used for all kinds of applications, including go-karts and motorized bicycles, I even read some threads here about similar ones.
 

Psycledeliac

New Member
Oct 16, 2011
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Flint Michigan USA


That's a big honkin' shaft there! I am used to looking at the tiny little nubs on the weedwacker threads, but it looks pretty sturdy, I like that. It's only machined halfway up, I don't like that. The machined part is 5/8" with a 3/16" woodruff key.

Now I gotta figure out how to affix it to the bike.



Re-located the brake to the other side of the mount to get it out of the way.

Held this motor like this for hourz while staring at it, letting the image burn into my head and my inner fabricator do its calculating...

...my arm hurt


There is no clutch, so I will probably try the hinge-lift type system I've seen done here so many times.

And the drive roller?? Totally dunno yet
 

Psycledeliac

New Member
Oct 16, 2011
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Flint Michigan USA
I busted out the hacksaw and cut up a hanging bracket for a HUGE old television. The T.V. don't work so well anymore but is absurdly heavy and the bracket is c-channel steel. Pretty sturdy. Got both for free. Yay




It's not quite big enuff for the bolt pattern of the motor mount, so I hammered part of it into an angle-iron sort of thing, and I can double it up, that should make it a bit stronger, too



I also found some cheap casters for ninety-seven cents at the local Harbor Freight, popped the plastic axles out, and they struggled onto the shaft pretty nicely, my new drive roller! Maybe. I think I can hold them in place with a couple shaft collars or something.




Then I drilled the holes for the bolt pattern, easy, and tried a cheap hole-saw made for wood to drill the shaft hole, hilarity ensued as I rubbed the teeth right off of it. Off to HomeDepot and eleven dollars later I had me a bad*** 1 3/8" metal hole saw and a big hole drillt into my bracket. A quick mockup over the wheel looks promising! I'd like to see a bearing on the other side of the shaft, but will worry 'bout that later, right now I just wanna see if this even works.



Next-- How to get it on the bike already
 

Psycledeliac

New Member
Oct 16, 2011
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Flint Michigan USA
After examining every aisle in several hardware stores, I conjured up a rather easy, if not elegant, mount and lift design mechanism. A few large cable clamps and some more hacksawed bracketry. Behold!



I had to split the c-channel cuz it wasn't wide enough to reach the bolts, I couldn't find an appropriate existing bracket, I guess I will hafta figure out how to bend up a metal plate to suit my purpose, but in the mean-time, I can live with this








 

Psycledeliac

New Member
Oct 16, 2011
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Flint Michigan USA





It is getting closer! I am anxious to give it a test run, but Safety sez I should rig up a throttle and kill switch first. But I am not seeing any reason why it shouldnt at least move itself under its own power right now!

Excitement!

and patience....

Oh, I plan to move that gas tank to the other side of the rack, but it's already like that and will work for test purposes.

Pedaled it around a bit, not too weird. The whole deal weighs around 50-60 pounds, I'm guessing. Feels quite lopsided when still, but riding it, it hardly makes a difference, that's a relief!
 

cannonball2

Well-Known Member
Oct 28, 2010
3,662
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Colonial Coast USA.
How are you planing on securing the drive rollers? looks like the crank is not drilled on the end? Generally I secure a slip fit roller by compression into 3/8 rubber disc backed up by a washer. I have gone totally to oak rollers. Cheap and easy to make in various sizes for different ratios.
 

Psycledeliac

New Member
Oct 16, 2011
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Flint Michigan USA
Hi Cannonball, thanks for looking! :)

No, the crank is not drilled, and I picked out the woodruff key. I was thinking of sandwiching the roller wheels in between a couple of shaft collars, compressing them with a clamp, and while clamped tightening the set screws. The problem is that shaft is only machined to 5/8" halfway up, then it's slightly bigger, and the next size up collar is too big. So I gotta either file out the inside of a shaft collar or make a sleeve for the bigger collar.

Yes I did read the cheap easy drive roller thread, some really good ideas there! Rubber washers against oak rollers, I like!

But first, I gotta see if and how this thing runs, and work out the bugs, before I go experimenting with rollers.

Right now I am trying to figure out how to attach a throttle cable, the throttle turns kind of to operate and the linear motion of a cable is giving me some trouble. But I will get it eventually!

I'm dyin' to give this thing a test run! Lol!

Thanks again :D
 

wayne z

Active Member
Dec 5, 2010
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louisiana
It would not be hard to drill and tap the end of the crankshaft. Drill it with the motor running and clamped or bolted down to something solid to insure the hole stays parallel to the shaft. Similar to the way shafts are drilled in a lathe.
 

wayne z

Active Member
Dec 5, 2010
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louisiana
Don,t try to file it while running, the file will bounce off the high spot and drag on the low spot and make it out of round worse. I've learned this the hard way before.
 

Psycledeliac

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Oct 16, 2011
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Flint Michigan USA
Oh, okay, thx for the warning Wayne.

Hello and thanks, Kev1n! Yes, I remember your bike thread from my lurking days, it is very similar indeed! I am glad to hear good things about these motors.

I let mine run for awhile in 'neutral' today, it IS loud!! And hoo-boy with the vibration! I watched a few bolts start turning themselves as soon as I started it. Tightened everything I could see down real good, this thing purrs like a kitten!

It has a self-regulating throttle mechanism where a little wing hangs near the cooling fan/flywheel and pulls against a spring thru the throttle and the wing and spring fight each other to hold the motor running at a steady rpm. As you load the motor and it slows the spring pulls harder on the accelerator because the wing has lesser lift, then upon acceleration the air from the fan blows the wing to close the throttle and this process goes back and forth.

Hooking a cable shouldn't hurt anything, but will probably keep it from auto-regulating to its neighborhood of 4000-ish rpm.
 

kev1n

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Sep 25, 2009
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wisconsin
Glad you saw the thread already and joined up.
I used lock washers and 2 bolts on everything and tightened the bolts together to keep them from coming loose. I guess loctite would work good as well. I hooked up a throttle wire to the carb like usual and it overides the winged governer which probably brings it up to 6500 rpm at WOT, I also added a stronger return spring on the carb to help bring it back to idle.
I Can't wait to hear how it rips up the pavement. I also like the avatar. brnot
 
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wayne z

Active Member
Dec 5, 2010
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louisiana
that's the govenor . most people disconnect them for MB use. you will govern it yourself with the hand throttle. It's only needed like on a mower or snowblower ect where a constant rpm is needed with varying loads, to keep the engine from bogging down or overspeeding.
These engines can be run slightly over governed speed for more power without any problems as long as carb is adjusted properly
Once you have it in"gear" it prolly won't vibrate as much.
 
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Psycledeliac

New Member
Oct 16, 2011
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Flint Michigan USA
Got a temporary throttle and kill switch hooked up for test drive purposes.







The switch ain't pretty, but it works. I also wanna rig up the throttle a little better and make it more easily removable, and add that stronger spring, but this'll let me see how it runs, which, by the way it does! And how!

It was finally dry enough out today to test it out, I pedaled it up to maybe 5-7 mph, grabbed the clutch bar, lowered the motor onto the wheel, and it went putt-putt-putt VROOOM!!! I had it maybe 1/3 throttle, and it was happily pulling me along at 15 mph or so.

Oh the joy of the feeling of my bicycle magically pulling itself along without any pedal power!!!

I'm gonna hafta get used to the clutch and throttle and how to brake all at once before I do any speed tests, maybe even rig the clutch to a cable.

I also have to get those shaft collars going to hold the rollers in place, I just had 'em pushed onto the shaft, and they moved around a bit

This is awesome and I am hooked and thank you everybody here you have helped me in so many ways just from reading all the old threads and thanks for the advice and support too!!

cvlt1