Engine timing

What is motor-timing?

Motor-timing means the times of opening and closing the valves in the proper position relative to the piston movement (relative to the piston position). For opening and closing, the camshaft is in charge, which is driven by the crankshaft. The timing is controlled by flywheels so-called "cams", which are mounted on the shaft. The cams may have a different shapes and width. Horex did experiments to determine the right timing for the opening and closing of the valves.
At the Regina engines, the camshaft is driven by a chain (older version) or gears (newer version) depending on the year of production. The camshaft of the Regina has two cams. One cam controls the exhaust valve, the other the inlet valve. The reciprocating motion of the cam is transmitted to the valves via pushrods and rocker arms. The camshaft driven by the chain is called "A" cam because the cam facing away the motor is marked with an "A". This cam is controlling the outlet valve. On the gear-driven camshaft, the rotational direction of the camshaft has changed, so that the "A" cam could not be longer used. The first gear-driven camshaft was instead marked with an "E" on the outer-side cam. This cam henceforth controlled the inlet valve. In the following years several different camshafts have been tested by Horex with different timing and cam heights. They all have different marks on it.
A table with the timing specified by the factory can be found in the operating instructions of your Regina.

Why do I adjust the timing?

The lower drive wheel of the camshaft, is located directly on the crankshaft journal. The connection from the crankshaft to the drive gear is made only by a cone without feather, pen or teeth. Solving the drive from the crankshaft (puller needed), it can be freely rotated through 360 degrees. If the wear of the valve timing chain, wheels or camshaft increases, the timing should be at least checked and adjusted if necessary.

What are the options to control the timing?

With gauges:
The most accurate method to control the timing requires one or more gauges that are aligned to the upper spring plate of the valves or directly on the valve caps. Additionally you need an exactly to TDC (top dead center of the piston) set degree wheel (motor-timing-wheel). The timing is then read directly from the dial gauges and compared with the specifications in the operating instructions.

With the 2mm method:
A further possibility without gauges is a so-called two millimeters method. This is methode is only possible because the cams of the intake and exhaust are symmetrical in all Regina engines (at Resident or Imperator, this method does not work). The method uses the property of the symmetrical cams in overlap position (exhaust valve closes, the inlet valve opens at exactly the same valve clearance), in which the piston must be at TDC. Thus we have two mechanical points that we can accurately identifyed and adjusted to each other. But why 2 mm valve clearance on both valves? The overlap position is determined by detecting the friction on the pushrods. This is by rotating to the pushrods and found the binding. The 2 mm Valve clearence bridges the flat acceleration and deceleration ramps of the cams because in this region of the cams the friction of the pushrods can not be accurately determined. The 2mm valve clearance is not a fixed value, which applies to each engine. It may happen that the friction can be better observed at 1.8 to 2.2 mm valve clearance. It is important that the identical clearence is set on both valves.

If the timing is not correct, the piston has to be moved in TDC by leaving the cams in overlap position.

In principle, the procedure of the 2mm method works as follows:
Bringing the camshaft into overlapping position by rotating the motor in the rotational direction. Check whether the piston is now in the top dead center position. If it is, everything is OK. If not
, the lower wheel has to be released from the cone of the crank shaft and the position of the piston has to be moved in TDC by leaving the cams in overlap position. Then the lower wheel is tightened.



1) Install motor timing wheel and its 0-set exactly at top dead center position of the piston (the degree wheel shows 0 when the piston is at top dead center).
2) Set Two millimeter valve clearance on both valves.
3) Turn engine in direction of rotation until the camshaft overlaps. The position is found when the exhaust valve closes, the inlet valve opens and let both pushrods rotate equally easy. Now read the position of the piston gauge. If it shows  0 everything is OK and the camshaft is in the correct position relative to the crankshaft. If it shows a different value it has to be corrected, then go to Step 4.
Important! The cover of the control box must always fixed on the control housing, as this supports the camshaft and without it the results will be incorrect in step 2 and 3.
4) To correct the camshaft position the camshaft is allowed in the current position (overlap), solves the lower drive wheel of the crankshaft and the crankshaft is rotated to 0 position (TDC). Now the mother of the drive wheel is tightened slightly, so that the drive wheel is firmly back on the crankshaft end and we start again from step 3



Turn the piston in TDC position.

To do this we have to mount and adjust the engine timer before.

See Engine timer adjustment


Mountig the cam shaft.

In this position we can easily mount the cam shaft in this way:

In this position of the camshaft the valve clearance is adjusted.


Position of the cam shaft with chain drive.

If you have a cam shaft with chain drive, mount it in the position shown on this picture.


Position of the cam shaft with gear drive.

If you have a cam shaft with gear drive, mount it in the position shown on this picture.
Also it is possible that there is a mark on the upper right side of the sprocket and on th housing.

This mark applies only if still the original steering wheels and camshaft is installed.
Otherwise it is at least a good clue.


Timing adjustment with "2mm procedure".

If you don't have test gauges, you can use the 2mm procedure.
For this we leave the crank shaft in top dead position and mount the cover of the timing case to support the cam shaft.
Now we adjust 2mm valve clearance. I use a 2mm steelplate for this.


Cams in overlap.

Now we turn with closed timing case the crank shaft to overlap (in runnig direction of the engine).
It is the position when the outlet valve closes and the inlet valve opens.


This has to be done with closed timing case. Othewise the cam shaft is tilting. This picture is only for overview.


Valve push rods in overlap.

The position is reached, when both pushing rods are turnable with the same strength.
The engine timer should show zero degree in this position.
If not you have to dissolve the wormgear sprocket from the crank shaft by using the puller tool and turn the crank shaft into zero position.
The timing case cover can be securely removed, because the valve springs are slacked in this position.



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