Hi All, I have just bought a replacement cylinder head for my UK '77 CB550 F from California. I've fitted it on to the engine but when i went to put in the spark plugs from my old head, none of them threaded correctly. All seemed to misthread on the first couple of turns so i didn't force them. At first i thought it was maybe just dirt but they are all the same.
I was wondering if there is a difference between the US and UK versions or could this head have had them all re-threaded? Grateful for any advice.
Cheers, Gerry
