Hornsby Oil Engine

An oil engine can be a touchy beast. Here are complete instructions from one manufacturer on the care and use of theirs

Piston Rings
Ifnecessary to remove a piston ring, lift the point of ring, thentake a piece of thin flat steel or tin and push it under the ring,slide it round the piston; then slip in another piece, following onuntil four pieces are under the ring, when the ring will havesprung to the size of piston and will easily slide off.
GAS ENGINE MAGAZINE