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I got a call from my Bro the other day in a near fit. “Bro, I stripped my rear cylinder spark plug and I am leaving for the Republic of Texas rally in a few days. I’m screwed.”

“Take it easy, Bro. Get your bike on a trailer and bring it over. We’ll have Panman take a look at it.”

When it arrived we were able to take a good look at what he was talking about. There sat his ’06 Ultra, looking like it was ready to go save for the tape covering the rear spark plug hole. “You sure it is stripped bad?” When he showed me the spark plug, there was no question. The threads of the spark plug were no longer visible, instead it was loaded with shiny magnesium alloy as the rear cylinder had welded itself to the spark plug.

There is a lesson to be learned from this. On the older engines, the cylinders were steel. These didn’t have the problems that we have now. The cylinders are now a magnesium alloy, and the spark plugs are still steel. When you introduce enough heat, you create a metallurgical event that causes the two different metal types to weld themselves together. For this reason, it is important that you back out and reseat your spark plugs every 5,000 miles. The use of an anti-seize compound is also a good idea.

OK, lesson learned. Time to get the bike undressed and pull the head. First we removed the tank and the exhaust system. Next we removed the air cleaner and horn bracket. You might also want to make sure that the battery is disconnected.

Next we unbolted the fuel injection ports from the heads. This allowed us good access to the rear cylinder. The top pan cover came off easily enough. One of the bolts wouldn’t clear the frame to be removed, but we were able to slide the cover back enough to clear the bolt.

The rocker assembly was next. Two of the main bolts lie under the assembly. Once the rocker assembly was removed, we were able to remove the push rods. The lower head pan bolts can be started with a hex key to bring them up were you can comfortably get a wrench on them. Once this pan is removed, all four of the head bolts can now be removed.

The total time for the head removal was a little less than two hours, and was really a smooth job. The head was then run to the machine shop to have a step helicoil installed. For around $50, we were ready to go.

Time to throw her back together. Key here is take your time. And use plenty of loctite! We first inspected the new gasket kit. Make sure to clean off all remnants of the old gaskets, and then we reversed the process and began reassembling the cylinder.

The engine had less than 30,000 miles, and the valves appeared to be in great shape. The piston and rings are in the lower cylinder and were never moved, so we were able to start bolting the head back in place.

The service manual provided the necessary torque and sequence information. The reassembly took us about another 3 hours. Really a very simple project.

Once bolted together and the tank reinstalled, the moment of truth came. We turned on the ignition and hit the starter… damn, it started faster than mine! We listened for any vacuum sounds that would indicate a leak, and letit idle for a couple of minutes to warm up and rechecked it for any leaks. Everything looked great. Panman to the rescue again!

Words of wisdom, make sure that you back out and reset your spark plugs every 5,000 miles or so. This would have possibly prevented this from happening in the first place.

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