Starting problems

[carsubs13]

OK, got up 2day and it had snow'd so went out and jumped on tha 400ex and it cranked right up but then dies like 10 sec. later and wouldnt crank back, called my mechanic and he said it was the plug so tried taking out the plug but a 5/8 spark plug socket will not fit ( any idea of what size it would be?)

[hotrodtba]

18 MM, I believe.

[400exguy]

I had the same problem, yeh go to the local dealer buy the cheapest one they have even if its to long cut it off Thats what I did for like 6 bucks, mine fouled 2 plugs so far I only rode it 4 time though haha (this winter)