500 Twinair air filter, spark plugs & coil replacement

With the coils removed, you'll have access to the plugs. You'll need the 16mm spark plug socket and a long extension bar. Being an unorganised idiot, I couldn't find my 1/2 inch to 3/8 adaptor so couldn't use any of my lovely new 1/2 inch extensions or ratchets. I bodged a long extension from two shorter 3/8 ones I found lying around which seemed to work.



The plugs shouldn't be too tight, undo them and lift them out. If you've used an actual spark plug socket the plug should 'stick' inside it because they've got a rubber ring which grips onto the plug unlike a standard socket.

My plugs were apparently 10000 miles old, I have no idea if they are or not but I don't think these would last until 18000 miles.




To put the new plugs in, remove the ratchet handle, put the plug into the socket and screw it in by hand with just the extension bar. This helps you to get more feel to avoid cross threading it. Pop the ratchet handle back on to tighten them up.