When revolving the Crankshaft it will be noted that at each revolution the slot in the Vertical Shaft is constantly changing its position in relation to the crankshaft. The reason for this that the Bevel Gears have 22 and 23 teeth, so that by constantly revolving, the original position, before the Engine was taken to pieces, will eventually be arrived at. It is important to watch this, otherwise the timing may be wrong. After cleaning all the parts, revolve the engine until the piston is at top dead centre while at the same time the slot of the bottom Vertical Shaft Bevel Gear is exactly in line with the 2 studs that hold the Bevel Gear Bush (part No. K46 or K46-2). It may be necessary to revolve the flywheels several times before this slot comes into its correct position in relation to the piston. The Vertical Shaft with its couplings and cover can then be placed in position. It is now necessary to rotate the camshaft in the cambox until the chisel mark on the end of the camshaft (seen through the inspection plug K99) is exactly in line with the chisel marks on the bevel gear casing of the cambox and at the same time the slot in the top vertical shaft bevel gear is exactly in line with the 2 bevel gear bush studs, or in other words exactly at right angles to the crankshaft of the engine. The cambox can now be bolted in position. The four Screws holding the cambox should now be tightened up equally. The Vertical Shaft Cover should be pushed up into the top Bevel Gear Bush to enable the small Spring Jump Ring to be put into its groove, after which it should be pushed down until the Ring just lies on the bottom Bevel Gear Bush.
The Gland Nuts may now be tightened up.
The timing can now be checked by noting the time of closing and opening of the Valves. In the case of Standard K, K.N., and K.N.S., machines fitted with the 23 cam (K17). The Exhaust Valve should close when the Piston is 5/16" over the top of its stroke. The Inlet Valve should open when the Piston is 3/8" before the top of its stroke. NOTE. The No. 23 cam is now obsolete and No. 24 is supplied as replacement. In the case of K.S.S., and K.T.T., machines a 24 cam (K17/2) is fitted and the correct timing should give:- Exhaust valve closed 9/16" after top of stroke. Inlet valve opening 3/8" before top of stroke. To set valve timing accurately see Valve Timing with No. 24 Cam on page 12. It can also be checked by noting the marks on the teeth of the large bevel wheel and pinion. The marks must come together when the piston is at the top of its stroke and the points of the magneto somewhere near breaking position. If there are no marks on the teeth the line on the Camshaft must be in alignment with those on the front of the bevel gearbox. They should be looked at through the plug hole K99. It is essential that the tappet clearances be set at .012" on both valves for (see below for running clearances) checking the valve timing, i.e. Standard K, K.N., and K.S.S., engines. Measurements taken when engine is cold. In engines where the cam has received a considerable amount of wear the easiest way to check the valve timing is to see that the overlap is shared. That is, the Inlet Valve must open approximately the same distance before top dead centre of the piston as the Exhaust Valve closes after top dead centre.