=HOT FUEL PIPE.= If the fuel pipe that connects the tank with the carburetor, becomes hot, due to its proximity to the exhaust pipe of cylinders, vapor will be formed in the pipe that will interfere with the flow of fuel. =DIRT UNDER AUXILIARY AIR VALVE= will prevent the valve from seating properly, causing the engine to misfire at low speed. =CRACKS OR LEAKS= in intake pipe or gaskets will cause intermittent leaks of air and spasms of misfiring. Old cracks that have been brazed will sometimes open and close alternately causing baffling cases of spasmodic misfiring. =DIRT IN AIR INTAKE= will change the air ratio, and the increased suction will cause a greater flow of gasoline. Do not place the end of the inlet pipe in a dusty place, nor where oil can be splashed into it by the engine. Clean out periodically. “=LOADING UP=” of the inlet piping in cold weather on light load is caused by the mixture condensing in the intake pipe. The only remedy is to keep the piping warm, or to heat the inlet air. =CLOGGED OVERFLOW PIPE=, with engines equipped with pump supply will cause flooding, as the fuel does not return rapidly enough to the tank. (114) Kerosene Vaporizer for Motorcycles. An ingenious vaporizing device has been designed for the use of kerosene as a fuel for motorcycle engines, by the M. G. and G. Motor Patents Syndicate, Ltd., England, is described in Motor Cycling. The device consists of a comminuter, or vaporizer, which screws into the sparkling-plug hole in the cylinder, the plug being transferred to an aperture in the vaporizer, a feeder for regulating the supply of fuel to the vaporizer, and a throttle and air barrel, or mixing chamber, for the purpose of proportioning the amount of air and gas supplied to the engine, and for controlling the speed of the machine as in an ordinary carburetor.