Air compressor to gas engine

junglepig

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Oct 30, 2018
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218
... What would be cool is if someone made a 79cc engine into a vtwin.
I was poking around on Youtube for that the other day and found this. A guy has arranged two HT engines to make an in-line twin. I couldn't tell what kind of linkage he'd done from the right side of one to the left of the second one. He has it on his bike and looks to be ready to start it up soon.
 


junglepig

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Oct 30, 2018
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218
Yea I'm not sure either. This build will be my first real experiment. Either it works and i have a nice old looking v twin or i seize a compressor. The pressure isn't the real issue. My concern is whether or not the thin reed valves can withstand the actual combustion.
Good luck. I hope you have some success. It'll be a neat project, and I'm sure you'll learn neat things doing it. We'll be watching.
 

RocketJ

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Dec 2, 2017
Messages
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I was poking around on Youtube for that the other day and found this. A guy has arranged two HT engines to make an in-line twin. I couldn't tell what kind of linkage he'd done from the right side of one to the left of the second one. He has it on his bike and looks to be ready to start it up soon.
That looks quite interesting. My guess is that he has the clutches running at similar lengths and both engines act independently.
 

RocketJ

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Dec 2, 2017
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Good luck. I hope you have some success. It'll be a neat project, and I'm sure you'll learn neat things doing it. We'll be watching.
Thanks. It's been a big goal of mine to create my own motorcycle from scratch. If it comes out the way i hope, I'll have something close to an indian powerplus with some personal details of my own.
 

curtisfox

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May 13, 2010
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Yea I'm not sure either. This build will be my first real experiment. Either it works and i have a nice old looking v twin or i seize a compressor. The pressure isn't the real issue. My concern is whether or not the thin reed valves can withstand the actual combustion.
I say try the stock reads, you can always change later.........Curt
 

RocketJ

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Dec 2, 2017
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109
I say try the stock reads, you can always change later.........Curt
I'm gonna give it a try. Worst case scenario, i can just remove the stock reeds and throw on a 10 dollar 2 stroke valve kit. I'll update when i start getting all my parts. Work's been crazy this year and my sh**ty contractors haven't made my finances any easier.
 

Will'smotobikes19

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Apr 9, 2018
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1,645
So you want to make a vtwin 2 stroke? Some people have said that doesn’t work. 4 strokes require a cam to open and close the valves one could probably be positioned in the crankcase and a gear fitted to the crankshaft but I guess you’d need 2. Some lawnmower valves could be used. The rings are more like a 4 stroke I think since there is still oil/grease in a compressor crankcase might have oil control rings- not ideal for a 2 stroke.
 

Steve Best

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Sep 22, 2012
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1,236
I did the opposite 40 years ago. I was a kid take machining and compressors were expensive back then. I turned 4 stroke engines and refrigeration compressors into air compressors and sold to my buddies. My current garage compressor is a Coca-Cola refrigeration compressor I converted back then. It pumps up to 160psi before shut-off. The tank is a 18wheeler brake tank. For many years I ran it with a 5hp gas motor but after taking electrical courses I found a 1922 220v DC motor that I converted to AC.

I converted Briggs motors to compressors using a $10 sparkplug "tire fill" adapter sold at the time, and cam mods to improve the efficiency.

My most interesting was an Austin Mini engine with 2 cylinders brazed over to raise compression and double lobed exhaust cams. It ran on 2 cylinders and pumped with the other 2. Air intake was through the exhaust valve and out through the sparkplug "tire fill" adapter.
 

RocketJ

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Dec 2, 2017
Messages
109
So you want to make a vtwin 2 stroke? Some people have said that doesn’t work. 4 strokes require a cam to open and close the valves one could probably be positioned in the crankcase and a gear fitted to the crankshaft but I guess you’d need 2. Some lawnmower valves could be used. The rings are more like a 4 stroke I think since there is still oil/grease in a compressor crankcase might have oil control rings- not ideal for a 2 stroke.
I'm hoping for something more along the lines of a 4 stroke. The compressor has oil in the crank so i would only be injecting fuel through the intake. I'm going to see if i can use one cylinder head as a charging piston before the air gets pushed to the next piston. If that experiment works then i will test to see if a true v twin is possible. I really won't know until i tear down the compressor and see how everything is assembled. A 2 stroke twin ia definitely possible. The gentleman in the video above had made one.
 
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