I need your help.  Any ideas on how to get this going?

First attempt:
Second Attempt:

Third Attempt:

These are Comments on the 3rd Attempt:

Thank you for all your comments.  I tallied all 117 suggestions, so far, from hackaday, video comments, and emails.  Here is what you said and my responses.

15% Check valves are too slow to close.  Evidenced by the gasoline splashing back and fire coming out of the intake manifold.  Try cam controlled valves  --Lou: I plan to replace the exhaust valves with one cam-controlled gate valve.

15% The flywheel should be more massive.  Maybe try a wheel and tire  --Lou: I am probably being stubborn, but I have seen a good fire send the flywheel around through all the cycles.  I think it will be fine.  I plan to focus on getting fire every time, and then look at the flywheel.

15% The compression is too low.  The valves should be moved closer to the cylinder to decrease space and increase compression. –Lou: I wrapped foil around the piston and got a nice increase in compression.  I also plan to move the valves closer to the head, as suggested, to increase the compression ratio.

13% The spark timing is off. Get rid of the string and micro-switch set up. You need something a lot more stable.  Try timing gun. –Lou: See next comment.  I think the grill igniter is the main problem.  If not, I will switch to a cam driven spark.

12% Grill igniters do not have reliable timing.  When you push the button there's a short, unpredictable delay until the first spark. –Lou: I totally agree.  I just went out and bought a coil, points, and condenser, at an AUTO PARTS store, but don’t tell anyone.

12% You aren't getting the right air/fuel ratio Your fuel isn't atomizing properly with the bubble system, so there is an inconsistent fuel/air mixture with each cycle. –Lou: I was totally ready to give up on my bubble carb, but then someone posted this: http://www.youtube.com/watch?v=xWBWhRZiZ9E

5% This looks dangerous. –Lou: We are not having fun until someone gets hurt   I will wear goggles, at least.

3% The stroke is way too long for the air to properly compress and combust. –Lou: Maybe. I will work on other stuff first and then look at this.

3% The spark may be too weak. –Lou: See comment above about replacing grill igniter.

2% Build a better starter motor.  –Lou: Maybe.  I hope I don’t have to.

1% a choke cuts the amount of air through the carburetor to enrich the mixture -- your 'choke' just lets more air into the cylinder and less fuel, thus leaning it out. –Lou: my “choke” allows me to change the fuel/air mixture.  I think that is all I need.

1% This can't be done without precisely machined parts. –Lou: You are right, so far.

1% Hundred if not thousands of engines are operation with intake valve what is essentially a check valve & the valve timing with that is automatic.  –Lou: I plan to stick with a check valve on the intake side, for now, at least.

1% Just buy an engine at the hardware store!  --Lou: I wish had thought of that, a year ago, when I started this project!! 

These are comments on the first attempt:
Thanks to everyone that made suggestions so far.  Here is what you are saying, and here are my plans so far.  I am working on it more this weekend.  I will post pictures as I go.  -Lou

Add Exhaust Port 25 A LOT of you pointed out that there was no exhaust port.  I was hoping that enough would slip by the piston, but I think you are right.  I will drill a hole in the cylinder at the very bottom of the power stroke.

Make Flywheel Bigger 13 Many of you noticed that the flywheel spun partially around and then stopped, when it was trying to open the valves.  Very good idea, but I am going to try to solve the problem with new valves that are at least 10 times easier to turn.  I think the current flywheel will be able to handle them.  If not, I will try a bigger one.

Change Fuel Mixture 12 The valves were actually set on the first engine to have slightly more oxygen than propane, but several of you said it needs to be 10-1, and I will change it to that.  Thanks.

Add more gasses 10 A few of you thought that there were not enough gasses being let into the cylinder, with each cycle.  I am worried about this too.  I am changing to a cam system that will hold the valves open for more of the cycle, but worry that the torch heads will not allow enough flow to support continous explosions.

Change Timing 5 Some noticed that the timing was not optimal.  The spark should happen at top dead center and the fuel should be let in right after exhaust.  I added a cam system to allow optimum timing.

Use air, not oxygen 3 Air is about 20% oxygen, and that is the only part of air that combustion uses.  An oxygen tank was only $8.  An air tank would have been $50, and I would have had to pump it up.  There are those little spray air cans, but no way to hook pipe to them.

This is a 2-cycle engine 2 Yes, I thought this would be easier than a 4-cycle, to build

Replace grill igniter with… 2 A few are concerned that the grill igniter will not be able to spark fast enough.  Hmm.  It is pretty fast.  I will leave it for now and fix other stuff first.  I may have to change it later

Add Cooling 2 A couple people thought that when this engine does start running, it will heat up and leak badly or seize up.  I have plans to add a 1/4" copper pipe water cooling system, but wanted to get it running at all, first :)

Stabilize Connecting Rod 1 Some of you noticed that the connecting rod was pretty loose in the cylinder.  I will add a 1" to 1/2" copper pipe adapter to guide the 3/8" rod.

Add a kill switch 1 A few of you thought ahead to when this engine actually starts running and worry that I could not stop it, if it started going too fast and parts started flying off!  Good point.  I actually have one.  I can turn the battery off to the spark.

Make Cylinder Stronger 1 One person is worried the cylinder could explode.  So far, so good.  I hope not !!
Publish Email 1 One person wanted my email address to send me a PDF of a CAD drawing.  It is HowToLou@Gmail.com

Use Gasoline 1 One person suggested gasoline to replace the propane.  I need pressurized gas, because I am forcing in fuel while the piston is compressing.  Gasoline needs to be pulled in with an intake stroke, but I don't have that in this 2-cycle engine

Use Check Valves 1 On person suggested using check valves and I thought this was a great idea.  In fact, my first prototype used check valves, but since the gasses kept coming in, the first explosion just lit the gases at the source and I had an internal torch that never went out.

Add piston rings 1 One person suggested piston rings.  This is pretty tough with hardware store parts.  I hope I don't need this!!

Help Wrap Gifts!! 1 Oops.  That was my wife.

The two pictures below show some of the planned changes.  I will post more pictures as I build.


I totally reworked the engine, with new valves and a cam on the outside of the flywheel to open and close them at the right times.  The oxygen valve lets in 3x-4x what the propane valve does, because the pull wire is tied higher up the lever.  I drilled a little exhaust hole in the top of the cylinder, at the end of the stroke.  I also added a piston rod guide at the far end of the cylinder.  It is not pushed onto the cylinder, in this picture.  That is why it looks crooked.  

Unfortunately, after all this rework, it does not work as well as it did before.  Grrr!  I can't seem to hear any oxygen coming out.  I will work more on it to figure it out.

I will say that the wheel turns much more freely, with the new easier valves.  This may mean I don't need a bigger flywheel.  We shall see.

If you want to email me, I am at HowToLou@gmail.com


12/19/2012 - I have done some experimentation, and pretty sure that the oxygen tank has much too small a flow rate to supply the needs of this engine, at speed.
I am looking into using compressed air, instead.  That will provide MUCH more flow.  I will try propane.  If that does not work, I am thinking about making a carburetor and
using gasoline.  I hope the propane works.  

I hooked up the air compressor to do a test, and found out that these air regulators that are labeled from Zero to Max, do not actually go to Zero.  Meaning, they can never be completely turned off.  This means they can't be used as valves.  I am now thinking about switching to a valve that is smaller and easier to turn than the original.  Hopefully, it will be loose enough so that the flywheel will be able to turn it.  Does anyone know of valves that shut all the way off, but are fairly easy to turn?  If so, please mail me at HowToLou@gmail.com.  Thanks.

Jan 1, 2013 - My basic problem has been getting a consistent fuel / oxygen mix.  I have done some experimenting with gasoline, and found it easier to get a good mix.  I have switched to this new gas/air configuration, but have not had time to play with it yet.  I will post my results. Ideas?   Please mail me at HowToLou@gmail.com.  Thanks.

July 21, 2013 - Here is a picture of my 3rd attempt.  I have changed from a 2-cycle to 4-cycle design  Also see the video at the top of this page.