MikeJ
Member
Hi Guys -
I put one together. . . An electric drill driven one-way clutch starter assembly for the 2-cycle engines. There should be some pictures attached.
The one-way clutch roller bearing was made by Torrington. I got it from a local industrial parts supply house. It measures 1/2 inch internal diameter, 3/4 inch outside diameter, and about 4/10 of an inch wide. I paid just under $13 for it and out the door I went.
I cleaned the mating surfaces of all oil and grease and used a small vise to press the bearing into an Ace Hardware shaft collar, 3/4 inch internal diameter and 1 1/4 inch outside diameter. The collar has a setscrew. The bearing purposely gives a tight fit so it will not rotate in the collar. I am surprised they assembled so well.
The big socket is the cheapest, most beat-up 1 1/4 inch socket I could find. An adapter allows this to be driven by a 3/8 inch shaft. The smaller shaft is driven by the electric drill.
The bolt was 3 inches long and less than $2 from Ace Hardware. It is .496 inch diameter. Take the one-way clutch bearing with you when testing which bolt best engages the clutch bearing. A .498 inch diameter shaft engages more reliably than a shaft of .496 inch diameter (measured with a micrometer). I cut off excess bolt thread and used a Scotch Brite pad I had to polish the bolt just a bit. A file and an hour of effort can trim down the end of the bolt to 3/8 of an inch square. My bolt is not perfectly square; it is even a little sloppy. Place a layer or two of electrical tape over the end sides before putting on any socket and the socket will stay on without a problem.
To keep the shaft collar in the large socket, back out the set screw until two threads or so are visible, then press the collar into the socket with a little force. When assembled, the drill will spin the big socket, the collar can't avoid spinning with it, the one-way clutch engages the filed bolt, which drives the smaller socket. (Expect a little wobble when spinning; this is not precision-made equipment.) When the engine starts, the smaller socket and bolt spins fast, and the one-way clutch disengages. Now just slowly pull the starter assembly away from the magneto nut. (I recommend you wear leather-finger gloves from Home Depot to avoid skin injury.) Note there is no hole drilling or thread tapping involved on the starter assembly.
I am going to cut a hole in the magneto cover to get to the 14 mm nut. Then cover the hole with velcro or tape while the engine is running.
I have not tried my assembly on my engine yet. But I know the one-way bearing will easily hold 10 ft-lbs of torque, a lot more than necessary to start an engine. I have no doubt it will work just fine.
MikeJ
I put one together. . . An electric drill driven one-way clutch starter assembly for the 2-cycle engines. There should be some pictures attached.
The one-way clutch roller bearing was made by Torrington. I got it from a local industrial parts supply house. It measures 1/2 inch internal diameter, 3/4 inch outside diameter, and about 4/10 of an inch wide. I paid just under $13 for it and out the door I went.
I cleaned the mating surfaces of all oil and grease and used a small vise to press the bearing into an Ace Hardware shaft collar, 3/4 inch internal diameter and 1 1/4 inch outside diameter. The collar has a setscrew. The bearing purposely gives a tight fit so it will not rotate in the collar. I am surprised they assembled so well.
The big socket is the cheapest, most beat-up 1 1/4 inch socket I could find. An adapter allows this to be driven by a 3/8 inch shaft. The smaller shaft is driven by the electric drill.
The bolt was 3 inches long and less than $2 from Ace Hardware. It is .496 inch diameter. Take the one-way clutch bearing with you when testing which bolt best engages the clutch bearing. A .498 inch diameter shaft engages more reliably than a shaft of .496 inch diameter (measured with a micrometer). I cut off excess bolt thread and used a Scotch Brite pad I had to polish the bolt just a bit. A file and an hour of effort can trim down the end of the bolt to 3/8 of an inch square. My bolt is not perfectly square; it is even a little sloppy. Place a layer or two of electrical tape over the end sides before putting on any socket and the socket will stay on without a problem.
To keep the shaft collar in the large socket, back out the set screw until two threads or so are visible, then press the collar into the socket with a little force. When assembled, the drill will spin the big socket, the collar can't avoid spinning with it, the one-way clutch engages the filed bolt, which drives the smaller socket. (Expect a little wobble when spinning; this is not precision-made equipment.) When the engine starts, the smaller socket and bolt spins fast, and the one-way clutch disengages. Now just slowly pull the starter assembly away from the magneto nut. (I recommend you wear leather-finger gloves from Home Depot to avoid skin injury.) Note there is no hole drilling or thread tapping involved on the starter assembly.
I am going to cut a hole in the magneto cover to get to the 14 mm nut. Then cover the hole with velcro or tape while the engine is running.
I have not tried my assembly on my engine yet. But I know the one-way bearing will easily hold 10 ft-lbs of torque, a lot more than necessary to start an engine. I have no doubt it will work just fine.
MikeJ
