Spark plug problem

[Joe]

I have a CB750 1973 and have removed 3 spark plugs using a deep socket 18mm with no problem.  However, I can't get the last one at all.  The socket won't even fit over the plug.  It's the second one on the left side and I can't even see into the hole to see what the problem is.  Is there a different size that might be in there? Or is it an exceedingly tight fit?  I even ground my 18 mm socket with no luck.

[JonnyHonda]

I have always found sparkplug socket sizes to be confusing. I have two, 16mm and 12mm and the 12mm is the larger.

My F had one plug with the nipple fitted and a different plug cap, it wasn't until I got a deeper socket that I could remove the plug.

[CBen750F1]

mate the only socket that will get that spark plug out easy, is the factory one... trust me.... if you look at the rocker cover they evn had to machine a relief in it to get the plugs is... i have tried all sorts of sockets, and the factory one is still the best... hope this helps..peace