Adjusting Tappets on the BMW R60/6
Due to the horizontal layout of the BMW Boxer engine, tappet adjustment is very straight forward.
The only critical parameters being that the engine is cold and that the correct crank/cam position is used.
Due to the horizontal layout of the BMW Boxer engine, tappet adjustment is very straight forward.
The only critical parameters being that the engine is cold and that the correct crank/cam position is used.
With both spark plugs removed the engine can be turned using the back wheel with the bike in gear, until the OT (Oberer Totpunkt) marking is visible in the window.
In this position both cylinders are at their top dead centres, one on the compression stroke, the other between exhaust and induction.
Both rocker covers should be removed by unscrewing the two nuts hidden within the cylinder fins (shown here); followed by the main centre nut on the rocker cover.
A drip tray will be needed to catch the inevitable oil drips.
To determine which cylinder is on its compression stroke, the rocker arms can be "wriggled" by hand. Only one cylinder will have no pressure on both valves (and therefore rockers which are free to move just slightly) and this cylinder cab be adjusted first.
Adjustment is made by sliding the correct thickness of feeler gauge between the rocker and the valve top and opening the lock nut to allow the adjustment bolt to be turned. The correct adjustment is when the feeler gauge is a sliding fit in the gap.
Feeler gauge specification is:
Inlet = 0.1mm
Exhaust = 0.15mm
Rocker end float can be checked by trying to move the rocker up and down, and observing the amount of free travel. If correct then there should be very little movement just enough to see the oil film where the rockers meet the mounting blocks change slightly.
If end float is too much, then it can be adjusted by moving one of the mounting blocks towards the rocker.
To do this a woodwork clamp with some sockets or spacers can be used to apply a slight squeezing force to the mounting blocks. This force should be applied with one of the cylinder head nuts loosened, so that the block can be moved enough to set the correct amount of end float.
Set the spacing so that there is essentially no clearance or free play here; but the rocker mustn't be tight.
Once one side of the engine has been adjusted, the rear wheel can be turned to rotate the flywheel one whole turn and then the other side adjusted in the same way.
Once end float and clearances had been set the rocker covers are replaced (reusing the gasket). The centre nut should be tightened to a maximum torque of 14ftlb and then the two m6 nuts added behind the fins.
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