=INLET VALVE LOCK= may be worn in such a manner as to prevent the valve from seating during the idle strokes and lose fuel, or cause overspeeding. =DETENT LEVER KNIFE EDGE= may be worn, or rounded off, so that the exhaust valve is not held open for the idle stroke. This defect will cause overspeeding. =SPEED CHANGING LEVER= may work loose and cause the speed to vary erratically. =GOVERNOR WEIGHTS= may be stuck on pins with dirt or gummy oil causing engine to overspeed. =LOST MOTION IN GOVERNOR GEAR= such as loose pins and bushings, worn rollers, or bearing surfaces will cause the speed to vary continuously. =LOST MOTION= on portable engines will cause the engine to run normally in one position, and overspeed in another. =WEAK OR BROKEN SPRINGS ON GOVERNOR= will cause engine to lose speed or die down altogether. Springs may be stiffened by pulling out the coils. =DRY GOVERNOR BEARINGS= or joints will cause binding and cause governor to act sluggishly. Use plenty of lubricant. =WORN ROLLERS= may cause a speed variation. Keep the governor well oiled, clean, and free from gum. If the knife edges are allowed to slip over one another, much wear is caused on the cams and if allowed to continue, sooner or later the engine will run away. Springs will weaken with age and hard usage. With belt driven governors see that the belt is tight and that the lacing is in good condition for a slack belt may allow the engine to overspeed. I advise that every purchaser of an agricultural motor read his instruction book with care, that is, locate all oil holes and note the action and purpose of every part. If in doubt as to any part of its use write the manufacturer of the motor. (132) Throttling Governor Troubles. =STICKING GOVERNOR VALVE= will cause the engine to overspeed; remove the gum and dirt. =LOOSE PINS OR BUSHINGS=, or lost motion in any part of the governor mechanism will cause irregular motion or running; be sure that the bearings and joints are well oiled. =STUCK PINS= will cause the engine to overspeed on light loads, and fall down on the normal load, or cause racing. =WEAK OR BROKEN SPRINGS= will cause the engine to lose speed or to lie down altogether even on light loads. =STIFF GOVERNOR SPRINGS= cause the engine to speed up. =SLIDING COLLAR= stuck will cause racing or a fluctuation in the speed. Keep the governor well oiled, clean, and free from gum. The governing valve should be removed from its care frequently and thoroughly cleaned with kerosene. Deposits of carbon and gummed oil at this point are dangerous because of the likelihood of their causing overspeeding. (133) Valve Gear Arrangement. The valve operating mechanism lay-out depends upon the cylinder and valve arrangement, and consequently varies in detail with different engines. [Illustration: Overhead Valve Arrangement of the Fairbanks-Morse “R E” Engine. ]