Spark Plug Maintenance

Changed the anti-freeze in the R² today and while I had the tank off pulled the plug to check it. Was surprised to find quite a bit of rust around the base of the plug even though it is less than three months old and the "coil" on this engine seals up the recess in the head. So Condensation was at work and corrosion was the result as you can see below. I use anti-seize on my plug threads. Love the stuff for this kind of application.

The threads are fine and well lubricated. The plug came out like it was brand new. At any rate pulling the plugs regularly and keeping the corrosion (if any) cleaned off and threads freshly lubed will keep everything happy with the plug. I now coat the plug base and the threaded tip with electrical grease too. I suspect it would also work just fine on the plug threads.

Just thought I'd give everyone a heads up to keep an eye on what is going on with the plug. Use as you will.

The top of that spark plug pocket is sealed by the coil, BUT.....the water is getting in through the drain hole on the right side of the head. There is a small hole to drain the spark plug pocket on the right side of the head between the two head bolts. You probably got some water in there from washing the bike, or riding in the rain or whatever and it stayed in there and rusted the plug.

And now that I have looked at it closer, I think it might not be a bad idea to tap that hole and plug it with a screw and gasket to keep the water out. You could always remove it to drain any water or blow out dirt. Yamaha puts that drain hole there so you can blow out the spark plug pocket BEFORE you remove the spark plug. This keeps any dirt or whatever from falling into the cylinder when you take the spark plug out.

mwakey wrote:

The top of that spark plug pocket is sealed by the coil, BUT.....the water is getting in through the drain hole on the right side of the head. There is a small hole to drain the spark plug pocket on the right side of the head between the two head bolts. You probably got some water in there from washing the bike, or riding in the rain or whatever and it stayed in there and rusted the plug.

And now that I have looked at it closer, I think it might not be a bad idea to tap that hole and plug it with a screw and gasket to keep the water out. You could always remove it to drain any water or blow out dirt. Yamaha puts that drain hole there so you can blow out the spark plug pocket BEFORE you remove the spark plug. This keeps any dirt or whatever from falling into the cylinder when you take the spark plug out.

I've heard of cases where the moisture built up under coil / boot couldn't escape when the motor got hot and the built up pressure forced the coil / boot to come off the plug. Might be another reason for the drain hole.

mwakey wrote:

The top of that spark plug pocket is sealed by the coil, BUT.....the water is getting in through the drain hole on the right side of the head. There is a small hole to drain the spark plug pocket on the right side of the head between the two head bolts. You probably got some water in there from washing the bike, or riding in the rain or whatever and it stayed in there and rusted the plug.

And now that I have looked at it closer, I think it might not be a bad idea to tap that hole and plug it with a screw and gasket to keep the water out. You could always remove it to drain any water or blow out dirt. Yamaha puts that drain hole there so you can blow out the spark plug pocket BEFORE you remove the spark plug. This keeps any dirt or whatever from falling into the cylinder when you take the spark plug out.

Thanks, didn't see the drain hole, I'll look at that you could be right. Thanks