O&RBike

For the actual engine mount in the bike we had to get a little more creative. We made a "saddle mount" out of some 1" I.D. DOM tubing. 
 
We split the tube and welded a flange along each edge. By loosening the 4 screws you can slide the motor fore and aft to adjust the chain tension...then lock it down.

 
 
 
 
 

Bent up a fuel tank bracket and plug welded it to the frame behind the seat...  
  Added a strip of self stick foam padding on it :  
  And clamped the tank into place :  

Looking at pictures of vintage BMX bikes online, we noticed a lot of the high end bikes of the day had a gusset behind the fork neck.    Of course we had to have one too....  



   
 

Both halves of the finished mount :
 
   

We figured out early on working on the floor or bench wasn't going to cut it. We turned down a piece of black pipe and clamped it in the vise. Then we could drop the front fork neck over it and it conveniently allows us to swing the frame around from side to side. It would work better if we squared the bottom end to clamp it...instead we just cranked down on it hard enough to flatten the pipe lol...    
  Here you see the new hub laced into the rear wheel and the 72T sprocket mounted...      
 
 

Both halves of the finished mount :
 
   

Looking at pictures of vintage BMX bikes online, we noticed a lot of the high end bikes of the day had a gusset behind the fork neck.    Of course we had to have one too....  



   
 

Both halves of the finished mount :
 
   

For the actual engine mount in the bike we had to get a little more creative. We made a "saddle mount" out of some 1" I.D. DOM tubing. 
 
We split the tube and welded a flange along each edge. By loosening the 4 screws you can slide the motor fore and aft to adjust the chain tension...then lock it down.

 
 
 
 
 

Having different mini bikes over the years we've fooled with lots of engines ..Clinton, Briggs, Tecumseh...but never one of these little O&R engines. Decided we better fire the motor and see what it was like.   We made a temporary motor mount and clamped it to the old truck-hitch "dyno" lol  we had made some years ago for testing small engines...      Haha...looks lost sitting on the plate.     Short fire up video:     You may notice the recoil wanted to push the rope back out while running...the ratchet pawls were not retracting properly and needed a little adjusting/servicing (thanks Wallfish !)

Motivating this thing is going to take some serious leverage given the lack of HP and torque. We're shooting for a final drive ratio somewhere in the neighborhood of 20:1. There's a company called Stanton that makes all sorts of engine powered bike accessories including this rear hub with LH and RH threads on each end. One side gets a freewheel flange made to accept the (#35 chain) drive sprocket ...the other side gets a freewheel bike chain sprocket so you can stop peddling when the engine takes over.   
 
 

Next I sourced an engine from Joe Webber out of Missouri. I told him it was a father son project we were working on and he couldn't have been nicer or more accommodating. 
 
He gave us a great deal on the beautiful 1HP Compact III...looks like nos !
 





       

This started out as one of those ideas where my son and I just sat around wondering if it would work and sketching it out...the next thing I knew we were building it ! 
 
We've all seen the Tom Thumb and Micro Bikes...not very practical being 6 inches off the ground. Or the 26" cruiser bikes powered by the 50cc import engines...cool but it's been done a million times. We wanted to try something a little different. The aim was to build a lightweight, small frame bike to ride around the school campus. There are some pretty stringent rules as to what will qualify as a "motorized bike" vs a street legal machine that needs to be registered and tagged. Your not going to bolt a West Bend 580 into a Schwinn and go ripping down the bike lane and get away with it. Campus police are hip to people bending the rules. 
 
My son thought an old BMX bike might be an interesting platform...and the Ohlsson and Rice being a vintage "Made in the USA" engine was appealing to me. The biggest challenge will be wringing every bit of that 1 HP from what I see as an oversized model airplane engine.
 
It may end up being an exercise in futility...but it will be an exercise in backyard mechanical engineering none the less and hopefully we'll both have some fun and learn stuff along the way.

We figured out early on working on the floor or bench wasn't going to cut it. We turned down a piece of black pipe and clamped it in the vise. Then we could drop the front fork neck over it and it conveniently allows us to swing the frame around from side to side. It would work better if we squared the bottom end to clamp it...instead we just cranked down on it hard enough to flatten the pipe lol...    
  Here you see the new hub laced into the rear wheel and the 72T sprocket mounted...      
 
 

Here's the bike blown apart...
 



 

And back from the blaster's with some assorted parts we collected:
 

This started out as one of those ideas where my son and I just sat around wondering if it would work and sketching it out...the next thing I knew we were building it ! 
 
We've all seen the Tom Thumb and Micro Bikes...not very practical being 6 inches off the ground. Or the 26" cruiser bikes powered by the 50cc import engines...cool but it's been done a million times. We wanted to try something a little different. The aim was to build a lightweight, small frame bike to ride around the school campus. There are some pretty stringent rules as to what will qualify as a "motorized bike" vs a street legal machine that needs to be registered and tagged. Your not going to bolt a West Bend 580 into a Schwinn and go ripping down the bike lane and get away with it. Campus police are hip to people bending the rules. 
 
My son thought an old BMX bike might be an interesting platform...and the Ohlsson and Rice being a vintage "Made in the USA" engine was appealing to me. The biggest challenge will be wringing every bit of that 1 HP from what I see as an oversized model airplane engine.
 
It may end up being an exercise in futility...but it will be an exercise in backyard mechanical engineering none the less and hopefully we'll both have some fun and learn stuff along the way.

Motivating this thing is going to take some serious leverage given the lack of HP and torque. We're shooting for a final drive ratio somewhere in the neighborhood of 20:1. There's a company called Stanton that makes all sorts of engine powered bike accessories including this rear hub with LH and RH threads on each end. One side gets a freewheel flange made to accept the (#35 chain) drive sprocket ...the other side gets a freewheel bike chain sprocket so you can stop peddling when the engine takes over.   
 
 

Here's the bike blown apart...
 



 

And back from the blaster's with some assorted parts we collected:
 

This started out as one of those ideas where my son and I just sat around wondering if it would work and sketching it out...the next thing I knew we were building it ! 
 
We've all seen the Tom Thumb and Micro Bikes...not very practical being 6 inches off the ground. Or the 26" cruiser bikes powered by the 50cc import engines...cool but it's been done a million times. We wanted to try something a little different. The aim was to build a lightweight, small frame bike to ride around the school campus. There are some pretty stringent rules as to what will qualify as a "motorized bike" vs a street legal machine that needs to be registered and tagged. Your not going to bolt a West Bend 580 into a Schwinn and go ripping down the bike lane and get away with it. Campus police are hip to people bending the rules. 
 
My son thought an old BMX bike might be an interesting platform...and the Ohlsson and Rice being a vintage "Made in the USA" engine was appealing to me. The biggest challenge will be wringing every bit of that 1 HP from what I see as an oversized model airplane engine.
 
It may end up being an exercise in futility...but it will be an exercise in backyard mechanical engineering none the less and hopefully we'll both have some fun and learn stuff along the way.

I started this thread over on the Old Mini Bike forum where I am a member but I thought the folks over here might enjoy seeing it too. I have gotten a lot of help over here since joining and I surely appreciate it. 
 
Helping my son build a small (BMX) 20" bicycle that uses a 1HP O&R engine as a power assist. The idea will be to pedal it up to approx. 10 MPH and then let the motor propel the bike to (hopefully) 20 MPH if geared properly.  Not sure if it work but it will be an interesting exercise for his mechanical engineering project.    
You may have to bear with me as I figure out how to cut and paste and upload images here....thanks !

Next I sourced an engine from Joe Webber out of Missouri. I told him it was a father son project we were working on and he couldn't have been nicer or more accommodating. 
 
He gave us a great deal on the beautiful 1HP Compact III...looks like nos !
 





       

Here's the bike blown apart...
 



 

And back from the blaster's with some assorted parts we collected:
 

Howdy all. Helping my son build a small (BMX) 20" bicycle that uses a 1HP O&R engine as a power assist. The idea will be to pedal it up to approx. 10 MPH and then let the motor propel the bike to (hopefully)20 MPH if geared properly.  Not sure if it work but it will be an interesting exercise for his mechanical engineering project.
 
I am new to these engines and have a few questions . It has a  1/2" sleeve with an internal taper that mounts to the crank pto. It looks to be  maybe a 10-24 grade 5 fastener holding it on...doesn't  instill a lot of confidence. Is there a torque spec for this screw..? Can I swap it out for a grade 8 socket head cap screw? 
 
Regarding the strange doughnut shaped exhaust manifold...can I loosen the cylinder head/barrel assembly just a little and rotate that exhaust to point in the direction I want it to and then snug it back down again? Do I need to change the gasket or seal once I break it loose? Is there a torque recommendation for this or just make it "tight"...?
 
Thanks in advance.
 
Gerry