INLETOILING

The reason why Matchless / AMC fitted inlet valve oiling before doing the same to the exhaust is pretty simple. With no lubrication the inlet valve starts to nip up well before the exhaust valve. It never totally nips up because the engine dies immediately the valve gets hesitant and doesn’t seat properly. In practice the engine gives a few spits back through the carb and then dies. The frustrating thing is that it never does this on a steep hill but rather on long slow inclines where the engine is asked to work just a fraction harder for just a bit longer than it does on ordinary give and take roads. On a very mild but long hill the rider is reduced to plodding up at walking pace just to humour the inlet valve.

The exhaust never nips up because it is lubricated by the oily residue from the combustion chamber. Remember this is all happening back in the total loss lubrication era before the oil control ring was normal wear. Much oil was pumped out the exhaust before the oil control ring was commonplace. Dave Blanchard is spot on with saying the exhaust valve could stick from an excess of oil. Lubricating the exhaust valve was never an issue at this stage of design. Stickiness from excess oil was.

What is the answer to these little amusements? Over the years I tried everything that came to mind. Upper cylinder lubricant, different valve guide material, aerosol sprays that got blasted on whenever possible and all to little effect. Then I was introduced to high temperature silicon grease and the problem magically went away. With a tiny smear of this wonder goo on the valve stem the inlet valve stays happy and my little Matchless climbs hills like it never has since leaving the factory.

So yes, inlet valve lubrication is necessary but until factories started fitting oil control rings as standard to all their range, exhaust valve lubrication wasn’t.