Dennis Country

Dennis Country

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Please send me an email if you wish to leave a comment. My website includes sections on the environment, green woodworking and some industrial history photos from Gwent, UK.

Decarbonising a Small 2-Stroke Engine (Decoke)

ToolsPosted by Dennis Hopkins Sat, January 06, 2018 02:50PM

An old brushcutter engine had carbon deposits in the top of the cylinder and piston, and in the exhaust port. It was decided to try to remove this because any dislodged pieces might damage the engine. For this I used some carburettor cleaner which slightly softened the carbon, a perspex scraper and fibreglass tip "pen". Of course it's essential not to damage the cylinder or piston, so using any tools harder than the cylinder/piston metal isn't recommended. The perspex is quite hard, part of an off-cut, and can be cut to shape with a hacksaw. The fibreglass "pen" is usually used to clean circuit boards etc., but worked well as a second stage tool here (the fibres are a health hazard to skin, eyes).

After a couple of hours most of the carbon was removed, except for some very hard material at the top of the cylinder, some of which was embedded in pit-damaged areas which will have to stay as it is. Some 1200 grade emery paper was used to lightly polish the piston (after photo was taken).

Of course this is also a good time to check the condition of the crankshaft, bearings, and wear on the cylinder, piston and rings, also that the ring(s) can move freely in their groove(s).

The engine seemed to run more smoothly after doing this, but it could be my imagination ... at least it ran.

The main tools used, plus carburettor cleaner