Thanks for replies.
An overview of the engine's construction: Base is 5mm aluminum; crankcase and cylinder head are both machined from solid alum.
Cylinder liner's material is some sort of stainless steel. Easily machinable though. I used plenty of time, when lapping it. Glad I did.
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Pearlitic cast iron is used for the piston. It has no oil grooves or piston rings, as it provides nice tight compression without them. Even without any oil.
It's the material that I highly recommend for pistons/cylinder liners for low-power, slow running engines. No wonder, that Jan Ridders prefers to use it on his engines...
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Carburetor on the left side is third or fourth version. Needle is from an ancient .10 glow engine. It still needs tweaking, maybe a new one(fifth version). Tried to make the needle system myself, but lack of lathe's top slide prevents turning any decent taper.
Currently, carb's throat size is 1.2 mm. Engine runs with that, but only at (too)fast speed. Positive thing is that no parts were flying out, when it cranked

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Testing different carbs with different throat sizes has gave me a hint of what the engine likes. Next version of the carb will have 0.6 mm throat, as it's the smallest drill size, that I have. If it's no go, then drill it to 0.7 mm, and so on.
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Sharp eyes might notice, that left side (inlet)valve doesn't have a tappet. Currently it's spring-loaded, as I ruined inlet cam by over-filing it.
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To be continued..


