Hawk Talk

[pete]

Originally Posted by Ariel Red Hunter

I was talking about J.A.P. engines the other day. Originally, all motorcycle engines had drip feed total loss oiling. Usually with a hand pump to give it a little more oil while hill climbing. About one pump every thirty seconds on a steep hill. The good feature of this system is that the engine always got fresh oil. The bad feature was that the engine didn't get enough oil to assist in cooling it. So, it limited horsepower. More horsepower means more heat. The oil was usually not fed to the bearings, it was squirted into the crank case, where the crankshaft whirled it into an oily fog, somewhat like a two stroke does. So, the J.A.P. engine for many years was a total loss engine, and, in fact, you can still buy an "80 Bore" J.A.P. engine new that is total loss oiling. For racing only, of course. But, the independent manufacturers of motor cycles that didn't make their own engines started to pressure JAP to provide an engine that had a dry sump system. So the 500cc and 350cc JAP's got a sort of hybred oiling system. It had pressure feed to the big end, and that was it. They had a v cast into the crank case walls so that oil spraying off of the crankpin onto the crank case walls, to run down to the v's and the vee's had a hole at the foot, and this allowed oil to drip on the main bearings. There was a hole cast in to the timing side case to allow oil mist to get to the cams and timing gears, which then ran down to a trench in the bottom of the timing case, where the cams would dip, picking up oil. But how to get the oil to the overhead valves and rockers? Crank case pumping. Yes, that's how they did it, by oil mist carried up by crank case pressure, and exhausted at the head through a ball valve which only let the air out. Usually a hose was attached to this valve to let the excess oil drip in the chains. While it sounds crazy, it worked....ARH

They still do to this day.... GM speedway motors use crank case pulese to move the oil.
the motor has a oil chamber on the side that the end of the crank shaft comes into the crank end is under oil as the piston goes up it sucks oil down the crank into the big end , as the piston comes back down the oil in the bottom of the crank case is pushed though a butterfly valve in the bottom of the crank case & back into the oil chamber...
The bottom of the cam chain is running in the chamber under oil & it takes the oil up
to the head and flicks it off at the top to oil the cam & valves... then it runs back down the cam chain tunnel to the oil chamber....

Weslake / Jawa / Godden speedway motors were/are a totol loss oil system they used the oil from a small tank in the frame the after it had been though the motor it was spat out though a butterfly valve onto the track...


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