1946 Model 18 Naive questions

With engines that have stood for many years its usual to drain the engine and try to introduce some oil to the cams ,valve gear  crank and piston . An expert on M18 engines will be along soon.

Hi Robert,

   Welcome back, it's less than 50p a week ! No expert, but some of this might help.

   The engine is a dry sump design so there should be a miminal amount of oil in the sump when the bike is running. Unfortunately these 75 year old pumps usually allow oil to drain from the tank into crankcase, so if you leave the bike any length of time, draining the oil will be a regular chore unless you fit a tap or one-way valve. Before you drain the oil out, kick the engine several times to splash oil around and be careful with the drain plug as this has a fine thread in aluminium and can strip easily. There is no direct oil feed to the valve gear on these engines and lubrication is by oil mist from crankcase pressure up the push-rod tubes. Remove the inspection cover and, as Robert says, pump a few squirts of oil as near the valves as possible and some down the tubes. While there, check the tappet clearence with the push-rods free to rotate with no up and down movement.

   Next, remove the spark plug and put 2 squirts of oil down the bore. Take off the primary chain cover inspection cap and check the chain tension and check oil level is up to the level plug. Do the same with the mag chain and oil, and check the gearbox oil level. Oil tank should be at least 2/3rds full. Make sure there's no old petrol in the tank and the taps both run free with fresh petrol. Lightly flood the carb and close the air lever, bring the piston to near the top of compression stroke using the de-compression lever. These bikes are fitted with tight-wire advance magneto, so set the lever at the half-way position and when the bike starts pull the lever tight for advance.

If the engine has drained its tank into the sump  then  be gentle if turning it over as it can  be damaged. Conversely  the big end and bearings  will have had  a good soak in oil and may have been preserved. When the riding season ends I try to change the oil to remove all the old contaminants so the engine is protected during the layoff,  which may turn into many years !.