I am amazed at how many errors there are in a design which has been around for such a long time. I encountered the same problems. I took some off from the oscillating arm and shortened the valve a little. I mounted the exhaust valve horizontally.I guess my thoughts on using reed valves is going to have to be implemented. I hadn't noticed that raising the cylinder to increase compression ended up with the intake valve making contact with the oscillating arm. Also sliding the exhaust manifold over to line up with the new slotted port put it in contact with the intake manifold.
Below are a couple of pictures of the collisions and then a few pictures of new manifolds using reed valves. The reed valves are in orange inside the manifolds.
There is still a bit of interference with the carburetor requiring it to be cocked on an angle to get the fuel hose on it but that might be solved with a 90deg hose pipe.
I pondered over what to use for the actual reed material. It needs to be very flat and springy so it will cover the port, seal properly and spring out of the way when pressure acts on it and reseal reliably. Then I thought of a small piece of feeler gauge. I made the dimensions of the manifold interior such that I could just cut the end off of a standard 1/2" wide feeler gauge and clamp it in place. This will also give me the ability to choose a thickness from a set that suits the application.
The problem right now is that I don't want to cut up my current set and considering that we are supposed to be isolated at home it's probably a bit irresponsible to go out to a store to buy a new set. If only they stocked feeler gauges at the grocery store
The idea might have to remain as drawings for a while. Sometimes not a bad idea because I might think of a better idea. I could probably make one of the manifolds (they are fairly simple) and substitute the feeler with piece of mylar sheet to test the idea.
COLLISION OF THE INTAKE VALVE
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INTERFERENCE OF THE INTAKE AND EXHAUSTS MANIFOLDS
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CLOSE UP OF INTAKE MANIFOLD WITH REED VALVE (flat orange)
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BOTH MANIFOLDS WITH REED VALVES (carb on an angle to accommodate the fuel hose connection)
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As far as the tiny clamps are concerned I made one extra. I should have made more. But I have the CAD file so it's just a matter of glueing and nailing down another piece of aluminum, setting the reference point and pressing go.Now that's some tiny, fiddly work. If it were me, I'd say you need to make extras because, inevitably, one of them is going to wind up missing ...