You need an 18 mm spark plug socket.
The most common reason for a Honda 400EX not to fire is the need for a new spark plug. Try replacing the spark plug to see if that fixes the problem.
18mm. But it has to be a thin wall socket. The stock tool that came with it is best if you can find one.
you need a special 18mm socket wth very thin walls. i got mine from pitposse.com, it cost $20.
13/16" - at least that is the size for my honda 520S snow blower.
if it is like my bike 2005 Honda foreman rubicon, you can find the spark plug under the seat. you have to take off the plastic part on the left side of the seat to acess the spark plug hole. by the way, the spark plug is very deep you probably need an extention, and a deep socket...
You need a 5/8" spark plug socket.
the spark plugs require a 5/8 inch spark plug socket.
18mm Deep style socket.
bottom of the motor. if you have a custom skid plate you may need to take it off and cut a hole in it.
You will need a 5/8 socket to remove the plugs from your 750 Honda motorcycle. A deep well socket is recommended.
To replace spark plugs, you can use a socket wrench, but a socket made for removing and replacing spark plugs is needed. This socket is relatively inexpensive and can be found at most auto parts stores.
You will need a 5/8 socket.