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Removing & Replacing Your Spark Plugs

TOOLS REQUIRED:

1 - Spark plug wrench OR socket w/ ratchet & 3" or 6" extension.

1 - Torque wrench.

1 - Feeler gauge set / plug gap tool.

1 - 3" piece of 3/8" ID rubber hose.

PARTS REQUIRED:

4 - New spark plugs.

Anti-seize compound.

INSTRUCTIONS

NOTE - This procedure is for ONE spark plug & wire. Unless you are very familiar with which plug wire goes where, I suggest only removing ONE WIRE AT A TIME to avoid a nightmarish game of musical plug wires later.

1. Remove the plug wire from the spark plug and position it out of the way.

2. With your plug wrench/socket, remove the old plug and place it in the box from the new plug. Mark the box with the cylinder it came from so you can go back later and read the plugs condition.

3. Take your NEW plug and check the gap between the electrode and the grounding post with a .024" (0.60mm) feeler gauge or plug gapping tool. If it's too tight, GENTLY pry UP on the grounding post. If it's too loose, LIGHTLY tap on the grounding post. Recheck and readjust as necessary until the proper gap is reached.

4. Now coat the threads of the new plug with anti-seize compound. This is important because it will not only lubricate the threads making it easier to install now and remove later, but it will ensure that the two different metals of the plug and head (steel/aluminum) are separated; preventing dissimilar metal corrosion in the treads.

5. Now wet the plug wire-end of the plug with a little spit and push the 3" piece of rubber hose onto the plug. Using the rubber hose will make getting the plugs seated into the holes MUCH easier, especially for cylinders 1 & 3 (which are forward of the intake manifolds).

6. Stick the plug into the threaded hole in the head and carefully engage the threads BY HAND ONLY using the rubber hose. Once the new plug is HAND THREADED ALL THE WAY DOWN, remove the rubber hose.

WARNING - NEVER START THREADING A SPARK PLUG INTO THE HEAD WITH A PLUG WRENCH OR SOCKET & RATCHET. IF YOU DO, YOU RISK CROSS-THREADING OR STRIPPING OUT THE THREADS IN YOUR SOFT, ALUMINUM HEAD; POSSIBLY RUINING YOUR HEAD. ALWAYS START THREADING SPARK PLUGS BY HAND.

7. Snug the spark plug down with the plug wrench or socket & ratchet.

8. Torque the plug to 22 ft. lbs.

9. Replace plug wire on the spark plug ensuring the air boot seals against the engine tin.

10. Repeat this procedure for the other 3 plugs.

Reading Your Plug's Condition

Look at the electrode end of your spark plug. What color is it?? Is it in good condition?? Is it oily??. . . You can get a good look at how well or poorly your engine is really running by reading the plugs. Here's a link to a GREAT website that has good clear pictures of spark plugs and what each condition means. It's an ultra-lite aircraft engine site, but plug reading is the same for all internal combustion engines.

Rotax "Reading Spark Plugs Page"

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