When I had the heads rebuilt by Randy Long I had him modify them for dual plugs. I have made that modification on two other bikes and I like the improvement in gas mileage and the smooth running even on lower octane gas. So I have to replace the stock coils with coils that have two secondary ports so each coil connects to two spark plug wires.

This bike came with a BMW electronic ignition that includes a “bean can” with Hall effect sensors that act like mechanical points.

The Hall effect sensors use a rotating magnetic field to open an electronic switch in the Hall effect sensor to stop current flow in the coil primary triggering a large voltage in the coil secondary. This is exactly what mechanical points do to trigger a high voltage spark in the spark plugs.

If you aren’t familiar with how coil ignition systems work you can read about how the /5 mechanical points ignition system works here.

• /5 Engine Ignition System
• /5 Ignition Coil

There have been some issues with the BMW electronic ignition. One in particular is that Hall effect sensors do not like heat and fail over time. When they do, you are stranded unless you have a second bean can with you. You can’t remove and disassemble the bean can by the side of the road.

I decided to remove the stock BMW ignition system and install a system that uses an optical switch for the points and a electronic ignition control module from Euro MotoElectrics. The ignition control module has three different ignition advance curves you can select from including one that works well with dual plug engines.

Resources

The following document describes the changes in timing required when using dual plugs. There is a link to in the document to a companion document showing how to modify the BMW ATU (Automatic Timing Unit). I don’t need to make that modification since the EME digital electronic ignition does not use the BMW ATU.

• 12 BMW 1977 R100RS Changes To Ignition For Dual Plug Heads

Here is a brief description of a Hall Effect sensor

• Hall effect sensor

Parts

I got all the ignition system components from Euro MotoElectrics. Their optical-electronic ignition, part# EDL-BOIGNS has optical points and three advance curve ignition control module. The EDL-BOIGNS web page has extensive technical information about what coils, spark plugs, spark plug wires are, and are not, supported with this ignition system along with other useful details.

The optical-electronic ignition requires 3 Ohms of primary coil resistance . For my application with dual plug heads, since the two coils are wired in series, each coil must have a primary coil with 1.5 Ohms resistance and have dual secondary coil ports for two spark plug wires per coil. The spark plugs should NOT be resistance plugs, as the ignition module is not compatible with them. The spark plug wires have 5,000 Ohm plug caps just like the BMW electronic ignition system does.

NOTE:
The earlier mechanical points ignition used by BMW requires 1,000 Ohm plug caps.

EME Part #	Description	Qty
EDL-BOIGNS	Digital Electronic Ignition	1
BMW-Cover	Bean Can Cover Plate	1
EDL-Coil1.5OHM	EnDuraLast 1.5 Ohm Dual Tower Ignition Coil	2
EDL-Bracket	Coil Bracket	1
Dual-PlugWSKit	Dual Plug Wires-5K Ohm	1

Tools

There is some soldering required. I use my 200/260 watt soldering gun, my soldering pencil and 60/40 rosen core solder.

Video

I made a video summarizing the installation process.

VIDEO: 1983 BMW R100RS Install Euro MotoElectrics Optical-Electronic Ignition System

Install Dual-Port Coil Brackets

The dual-port coils use a different bracket than the stock coils use. But, the brackets mount in the same location in the same holes as the stock brackets.

Since I powder coated the frame, I want to ensure a solid ground through the bracket and bolts to the frame as all the ground wires go there. I use my Dremel with a drum sanding disk and remove the powder coat around the bolt holes until the steel is shiny.

I reuse the original Allan bolts and wave washers to mount the brackets. I add a flat washer on the back of the bracket to ensure a good ground contact to the frame. I apply some NO-OX-ID “A Special” paste to the flat washer to prevent corrosion. This paste is conductive so it won’t interfere with having a good ground.

The brackets have a curved the legs. The bracket mounts so the legs curve to the inside.

Install Coils In Brackets

Each coil is 1.5 Ohm and comes with a small package of hardware. There are two types of spade terminals; a multi-prong terminal and two single prong terminals along with screws and lock washers.

The terminals mount in threaded holes on one end of the coil. I put the coils into the brackets to see which hole is at the top when the coil is mounted so the angled spark plug ports point to the front of the bike. I put the single spade terminal in the top hole and the multi-spade terminal in the bottom. I angle the top spade so it points to the inside.

The coils mount on the legs of the bracket with the two long bolts with lock nuts supplied with the bracket kit. The orientation of the coil has the angled ports pointing to the front of the bike.

After I mount both coils, I install the original black jumper wire between the single spade terminals on the inside of the coils.

Overview of EME Optical-Electronic Ignition System

The kit for the system includes an instruction booklet, a package with the optical trigger components, a bag with the ignition control module and a bag with wires, terminals and some tie wraps.

Optical Trigger Components

The optical trigger components include the optical trigger module and attached cable, a timing wheel sleeve that mounts on the end of the alternator rotor, a black timing wheel, assorted hardware, a small Allan wrench and some Blue Loctite.

The timing wheel fits spins in a “U” slot in the optical trigger. When the opening on the wheel passes between the legs, it sends a signal to the ignition control module that fires the spark plugs through the coils. When the engine is timed, I will put some Blue Loctite on the set screws in the timing wheel to keep the wheel securely attached to the timing wheel sleeve.

Ignition Control Module

The ignition control module comes with sticky Velcro to mount it where it gets air flow and not exposed to water, some wires and some terminal pins that you can solder on the end of the wires to plug them into the terminals of the ignition control module.

NOTE:
Based On EME’s recommendation, I tin the ends of the wires and insert the tinned ends into the terminals on the ignition control module.

A small screw driver is supplied to tighten the set screws on each terminal to secure the wires. There are ring terminals and male spade terminals that are soldered on the wires that go to the coils and the frame ground. There are some tie wraps to secure the wiring.

Bean Can Cover Plate

Since the optical-electronic ignition system replaces the stock BMW electronic ignition “bean can” that mounts inside the front engine cover underneath the alternator, I use the separate EME cover plate that fits into the bean can hole to seal it off.

NOTE:
If you have an earlier bike that uses the mechanical points without the bean can, you don’t need to install this cover plate.

Install Bean Can Hole Cover Plate

I start by installing the bean can hole cover plate. I put some engine oil on the o-ring that is supplied with the cover plate.

It installs with the original bean can mounting hardware which includes two Allan bolts, a large flat washer and a wave washer. I use some blue Loctite on the bolt threads to secure them.

Install Optical Trigger Components

NOTE:
I previously removed the stock alternator and replaced it with an EME 400 watt kit. This may affect what you need to do to get the timing wheel centered in the “U” slot of the optical trigger module as I explain below.

To have some more room to work, I detach the three phase wires from the spade terminals on the phase wires terminal strip.

Install Timing Wheel Sleeve and Timing Wheel

The timing wheel is installed on a sleeve attached to the crankshaft nose by the alternator rotor bolt. The Timing wheel is secured to the sleeve by two small set screws. The side of the timing wheel with the set screws faces to the front.

I use an electric impact driver to remove the rotor bolt and it’s lock washer. The impact driver gets the bolt loose but won’t turn the crankshaft.

NOTE:
If you use an Allan wrench to remove the bolt, put the transmission in 2nd or 3rd gear to immobilize the crankshaft while you turn the wrench.

The timing wheel sleeve mounts to the crankshaft with the rotor bolt. The rotor bolt threads are long enough that adding the sleeve does not require a longer bolt. But the original lock washer is too large to fit into the hole in the sleeve. The kit comes with a special lock washer that will fit in the hole.

You can install the rotor bolt by putting the transmission into 2nd or 3rd gear and then tightening the bolt to 14 FT-Lbs. Since that’s a low torque, I use my INCH-pound wrench set to 168 INCH-Lbs. Since my bike doesn’t have the transmission, drive shaft and rear wheel installed, I immobilize the crankshaft using a Phillips screw driver put between two teeth of the flywheel.

The timing wheel slides on the sleeve. I keep it loose until I get the optical trigger module installed and the timing wheel oriented correctly in the “U” slot.

Install Optical Trigger Module

The optical trigger module is mounted on an aluminum bracket. I attach the bracket on top of the alternator phase wires terminal strip.

NOTE:
The installation booklet states you can mount the optical trigger bracket either under the alternator phase wires terminal bracket or on top. I found mounting it on top was better for getting the timing wheel centered in the “U” slot of the optical trigger module.

The edge of the bracket can butt up against the “Y” terminal wire. I loosened the nut on the terminal and rotated the lug to provide clearance between the wire and the edge of the bracket.

I remove the two screws securing the alternator phase wires terminal board to the stator cover. The holes are tapped so the screws can be removed without removing the stator cover.

The optical trigger module comes with two Allan head bolts and flat washers. The bolts I removed from the alternator phase wires terminal strip have lock washers, so I use them to secure the Allan bolts.

NOTE:
The EME kit includes blue Loctite that you can put on the Allan bolt threads to secure them, but I decided to use the existing lock washers.

After test fitting the optical trigger module with the timing wheel in the “U” slot, the wheel wasn’t centered as much as I would have liked. So I used the flat washers from the EME kit and put them between the optical trigger module bracket and the alternator wires terminal strip to move the optical trigger module forward a bit more.

I carefully slide the “U” slot of the optical trigger over the timing wheel and then attach it starting with the bolt closest to the crankshaft as that’s easier to get to. Then I screw in the second bolt.

I move the timing wheel so the blade is as close to centered in the “U” slot as I can get it. I don’t want it to rub on the legs of the “U” slot.

I tighten the two small set screws on the timing wheel to secure it. Later I’ll adjust the timing wheel on the timing wheel sleeve to set the ignition timing.

I route the optical trigger module cable around the stator cover and up through the top, right side slot in the inner timing cover so it goes behind the inner timing cover. I put a zip tie around the alternator bolt to keep the cable from being pinched on the mating surface the front timing cover butts up against on the side of the inner timing cover.

I coil up the excess cable next to the starter motor. The optical trigger cable exits through the rear hole of the rear grommet on the back side of the inner timing cover. The battery (+) wire exits through the front hole of the grommet.

Install Ignition Control Module

The ignition control module should be mounted where it will get some air flow and not get splashed with water when riding in the rain.  It can NOT be mounted inside the front engine cover as it gets too hot inside. I choose to put it on top of the EME electronic voltage regulator which has a low profile. The gas tank is shaped for the BMW voltage regulator which is much taller than the EME voltage regulator. Piggy-backing the ignition control module on top of the EME voltage regulator should not interfere with the gas tank. This location gets some air flow and I’m going to point the terminals to the rear to provide some protection from any water that splashes up from the front wheel.

The EME installation booklet has a picture of the terminal numbers on the ignition control module and the wires that go to each terminal. A diagram of the terminal numbers with the wire colors that goes to each terminal is also shown on top of the ignition control module itself.

The terminals on the side of the ignition control module are embedded in a plug so you can remove the terminal plug from the module which makes it easier to put the wires into the terminals. I decided to use a toothpick and some white model paint to add a “1” and “6” above those terminals so it would be easy to get the wires on the correct terminal when I have the plug out of the ignition control module body.

Select Ignition Curve

There are two DIP switches on the other end of the ignition control module. These are set to select one of three ignition timing curves, or a test mode as explained in the EME installation booklet.

As delivered, the DIP switches were set for Curve #1. I want to use Curve #2 for my dual-plug heads. Pushing a switch up is “ON” and down is “OFF”. I need DIP #1 OFF and DIP #2 ON, which is the reverse of the settings for Curve #1.

Prepare Coil Wires

A BLACK, RED and BROWN wire are included in the electronic ignition kit. The BLACK and RED wires go to the coils and the BROWN wire is grounded to the frame using a coil bracket mounting bolt. There is a set of small plugs that can be soldered on one end of the wires. Based on EME’s advice, I don’t use the plugs but tin the ends of the wires with solder and insert the tinned end into the proper terminal hole in the ignition control module terminal plug.

I strip 3/8 inch of insulation off one end of the three wires. I use my soldering pencil to tin each wire. I  use my utility knife to scrap the solder a bit to reduce the diameter so the wires will fit into the holes of the terminal plug far enough to go past the set screws. Then I put some shrink tubing on the wires so it extends a bit over the tinned area and shrink it to provide some additional protection from water.

The picture below shows a stripped wire, a tinned wire and a shrink wrapped end of a wire.

I test fit the wires in the terminal block. I trimmed the ends off a bit so that the end of the shrink wrap would just fit inside the hole in the terminal block.

Mount Ignition Control Module

I want to measure how long the wires need to be so I can trim them. I install the ignition module on top of the voltage regulator using the sticky backed Velcro supplied in the EME kit. I clean the top of the voltage regulator and the bottom of the ignition control module with alcohol wipes and then stick the Velcro down to them.

Measure and Trim Coil & Ground Wires

Before I plug the wires into the correct terminal on the ignition control module, I dip the tinned end of the wires in some NO-OX-ID “A Special”, a conductive paste that prevents oxidation and corrosion. I use the small screw driver supplied in the EME kit to tighten the set screws to secure the wires in the terminal plug and then plug it into the ignition control module.

Then I install the three wires from the optical trigger module into the correct terminals on the ignition control module after dipping the pins in NO-OX-ID “A Special”. I do that to see how much room the coil and ground wires need to have to get past the three trigger wires since I want to assemble the coil and ground wires into a single cable.

I route the coil and ground wires to the terminals on the coils and the coil bracket bolt on the frame. I leave a little slack and trim them and strip the insulation.

The terminals supplied in the EME kit come with plastic insulators on them and are designed to be crimped around the bare wire. I prefer to crimp and solder so I use a utility knife to remove the insulators. I’ll use shrink tube to insulate the ends of the terminals.

I use larger diameter shrink tubing and slide it over the three wires to bundle them into a single cable. I put smaller diameter shrink tubing over the terminal and the wire to insulate and seal the ends.

I solder a ring terminal on the other end of the BROWN wire to fit over a coil bracket bolt. The RED and BLACK wires get female spade terminals soldered on their ends since they plug into male spade terminals on the coils. I use my 200/260 watt solder gun to solder the terminals.

Connect Coil & Ground Wires

I connect the BLACK coil wire to the lower multi-spade terminal on the right coil and the RED coil wire to the lower multi-spade terminal on the left coil. When I install the main wiring harness in the bike, I will attach the GREEN–Blue wire to the terminal with the RED coil wire.

I remove the front, left coil bracket Allan bolt and install the BROWN ground wire ring under it. The rear bolt will get the BROWN frame ground wire from the main wiring harness.

To take the strain off the wires, I use a small zip tie to attach the cable from the optical trigger Module to the cable of coil and ground wires I made. I’ll zip tie the cable of coil and ground wires to the spine tube after I install the main wiring harness.

Check Timing Wheel Sleeve Clearance From Front Engine Cover

On some BMW models, there is not enough clearance between the inside of the front engine cover and the face of the timing wheel sleeve. I put a smear of grease on the face of the timing wheel sleeve. Then I install the front cover, remove it and check the inside for any trace of grease on the inside of the cover.  There is none, so I have enough clearance.

NOTE:
If the timing window sleeve interfered with the front engine cover, I would use my Dremel tool with a sanding drum and remove some metal from the inside of the front cover until it clears the timing wheel sleeve.

NOTE:
There is a small circular discoloration on the lower part of the center rib. This is not grease.

I clean the grease off the sleeve timing wheel with a clean shop rag.

I can’t time the engine until I install the main wiring harness and battery.