Setting Static Ignition Timing on BMW K1200LT

by Paul Browne

With grateful acknowledgements to Davd Shealey and “Mick”for their help.

The objective of setting the static timing is to set a magnetic sensor at the end front end of the crankshaft at the right position in the crankshaft's rotation to tell the Motronic unit when to fire the spark. The sensor is called a Hall Effect Sensor or HES.

The first step in setting the static timing is to set the #1 piston to .010" before TDC. This took a while to figure out and to cobble together a way to make this measurement. I used a 1/4" metal rod about 15" long and inserted it through the #1 spark plug hole, first making sure that the ends were square and had no burrs and that the rod was clean. I used small C-clamp to affix a small box wrench to the left crash bar to act as a guide for the rod. I used a series of C-clamps to affix a gauge mount with a dial indicator. You have to attach the dial indicator to the bike vs. to a floor stand or to the lift to get an accurate reading. With all of the plugs out, I had someone turn the rear wheel to get the #1 piston to .010" BTDC. It does NOT matter if it's on the compression or exhaust stroke. This took several tries as the resistance of the valves springs made it easy to overshoot the desired point. When we missed the target, we did not simply reverse the rear wheel to get to the target. We went well back and always came up on the target going forward so that any slack in the engine would not give an incorrect reading -- this is an important fact to remember.

Next, remove the HES cover on the front of the engine. While it's easier to remove the HES sensor cover with the right side (as you are sitting on the bike) radiator removed, this not necessary particularly if you're not doing a cooling system service. Remove the fan shroud (2 screws). By removing the bracket that holds the right side crash bar, you can free up a stud on the radiator that allows you to lever the radiator up just enough to get a #30 torx bit in to remove the screws. I used a nice, smooth hammer handle and placed it on a meaty part of the radiator. The hammer handle was oval allowing me to rotate the handle to get the desired lever effect, and it did not move leaving my hands free. Sears sells a set of ¾” long torx bits for about $10. Using a 1/4" ratcheting box wrench I was able to loosen the cover’s screws. I found that holding the torx bit to the wrench with electrical tape worked great because adult fingers couldn't get in there to hold both the bit and the wrench.

Next, mark the HES plate so that you know its original position. Then, loosen the two hex bolts that keep the circular HES plate from rotating.

Next, find the place where you will tap into the orange wire at the HES sensor plug. This plug is in a box on the right side of the air intake box. Look for a box to the rear of the right radiator with lots of wires running into it. It has four screws holding the cover. When you take the cover off there is a frame with several connectors attached. This frame can be pulled out and up. Underneath is the HES plug. It has red, green, brown, orange and silver wires coming out of it. Use ONLY an analog multi-meter for the next step. Use a small straight pin or piercing probe to attach to the orange wire. Attach the negative lead to any ground wire.

Now, turn on the ignition. Imagine that you are in the position of the front wheel and that you're looking towards the back of the bike at the circular HES sensor plate at the front side of the engine. Underneath the plate is the end of the crankshaft. It rotates clockwise from your “front wheel's eye” view. If you rotate the HES sensor plate clockwise, you will retard the timing. Rotate the HES clockwise (remembering your front wheel's eye view). Your multi-meter will read the better part of 12 volts. As you rotate the HES plate counter-clockwise, the HES will trigger a relay and the voltage reading will drop to zero. Simultaneously, you'll also hear the relay click. Try it a few of times until you are sure that you have identified the trigger point. When you have, turn off the ignition and tighten the two hex bolts that secure the sensor plate.

Front of engine showing HES cover plate.

HES sensor plate and lockdown screws (1) HES cover plate behind right-side radiator hoses

HES plug in connector box beside air intake

Connector box is behind the “6” above

Note fan duct that is to be removed

HES sensor wires HES sensor plug

With gra