My buddy has a new to him EX400. I tried to take the spark plug out with the supplied plug wrench but it don't seem to fit down in the cylinder wall. Seems like it stops it from going onto the plug correctly. I tried the plug tool on a new plug and it fits perfect but when I try it on the machine it don't work.

Should I jut get a long socket and use that?

 

Thats strange I have no problems changing my plug on my 400 at all with the supplied wrench.

 

You must have the wrong wrench. The wrench that came with the EX in the toolkit will work just fine. Very few regular sockets will work. I took an old Craftsman 18mm and ground the walls thinner so it would fit.

 

My plug wrench that came in the tool kit wouldn't fit either. It'll fit over the plug alone, but not while it was in the head. I ground down the square edges off of it, and it now works fine.