Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Jin's holiday is extended not by choice but by the effort to contain the spread of the coronavirus. His work place will remain closed for a couple more weeks.


As for the piston, sorry to hear you are having problems.


This will not happen if you set up your engine properly and use a lot of marvel mystery oil in your fuel. 15 to 1 is a good mix.
The fuel should be Coleman fuel (white gas) or ethanol free fuel such as 100 LL aircraft fuel or another pure fuel.
Also retard the timing to top dead center and reduce the spring tension on the governor. This will get it slowed down.
You can run with just one slightly stretched spring or put two fresh but much softer springs on your governor weights.
You must also remove the crank case vent plug to run it. This way it will freewheel longer between hits and run much cooler.


I also like to shave 100/1000 off the piston top to reduce the compression and put a small chamfer on the top edge and the skirt.


I run mine alot and there are virtually no visible signs of wear.


Gil