12 BMW 1973 R75/5 Install Spark Plug Wires

I’m replacing the spark plug wires with new and reusing some spark plug caps and boots that are in good condition.  This isn’t a hard job and since the original spark plug wires have been in use for who knows how long, I want new wires.

Parts List

All I used is spark plug wire ( 12 12 8 036 124 ) and new spark plugs (BOSCH W6DC). I reused the rest of the parts after cleaning them up.

Reusing Coil Sleeves

Here are all the parts I need.

Plug Wires and Hardware

Plug Wires and Hardware

I used some Forever Black on the rubber boots and “000” grade steel wool to polish up the metal exterior the spark plug caps. The boots at the top go on the spark plug caps and the ones on the bottom go over the center tower of the coils.The cable on the right is the old one with a coil sleeve, and the one I removed is next to it.

I use a small blade screwdriver to gently pry the ends of the sleeve away from the wires so I can slide them off. I don’t want to deform them very much, so I go slow.

Removing Old Coil Connector

Removing Old Coil Connector

Preparing New Plug Wire

I used the existing wire to cut the new wire to length which I measured as 20 inches. Note that the end of the wire that goes into the coil has insulation removed and there is bare wire that you should include in the total length.

20 Inch Plug Wire

20 Inch Plug Wire

I strip 1/2 inch of insulation being careful not to nick the copper strands.

Strip 1/2 Inch for Coil Connector

Strip 1/2 Inch for Coil Connector

I spread the stands out and fold them over the insulation. This will provide a solid connection with the metal sleeve when it’s crimped onto the outer insulation of the plug wire.

Wire Folded for Coil Connector

Wire Folded for Coil Connector

I slide the metal sleeve over the wire so the copper strands are on the back side of the sleeve. I use my pliers to crimp the two buttons on the top of the sleeve and the band at the bottom of the sleeve so the sleeve is firmly anchored on the insulator.

Coil Sleeve Installed on End of Spark Plug Wire

Coil Sleeve Installed on End of Spark Plug Wire

I install the rubber boot that slips over the tower in the center of the coil. Then I put some dielectric grease around the bottom of the sleeve insert the sleeve into the center tower of the coil until all of the sleeve is inside the tower.

Dielectric Grease on Coil Lead

Dielectric Grease on Coil Lead

Plug Wire Inserted into Center Tower of the Coil

Plug Wire Inserted into Center Tower of the Coil

The spark plug cap has a threaded pin inside the insulator. I put the rubber boot on the wire and then screw the spark plug cap on the end of the plug wire until it is hard to turn indicating the wire is fully inserted inside the insulator of the spark plug cap. I put some dielectric grease on the end of the insulator and then pull the boot over it.

Dielectric Grease on Spark Plug Insulator

Dielectric Grease on Spark Plug Insulator

I route the plug wires through the larger hole in the rubber tank gasket and then insert the caps onto the ends of the spark plugs.

I set the gap on the plugs, put a little antisieze on the threads and snug them into the spark plug holes being careful not to over tighten the plugs.

Finally, I put the red plastic tie around the bottom of the rubber cable and wire routing block and tighten it.

Closing Rubber Block for Cable Routing

Closing Rubber Block for Cable Routing

Final Product

Here is the view from the saddle with the new plugs and plug wires installed along with the carburetors and new choke and throttle cables. It’s just about ready to fly again 🙂

Spark Plugs and Cables Installed

Spark Plugs and Cables Installed

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