spark plug

[honda400ex1999]

i can screw the plug in by hand part of the way but i have to use the wrench and it still does not seat all the way any idea what the problem is:confused:

[quadrider00]

the spark plug was probly crossed threaded at one time so the threads r damaged so they will most likely need to drilled out n tapped for a helicoil

[ae13291]

are you using the factory spark plug wrench for the 400ex?

[honda400ex1999]

ok for anyone how has this problem here is what i found out. the threads were fine since i was able to screw in part of the way by hand. so i looked into the hole and the threads look caked up with carbon build up. so i bought a 12x 1.25 plug tap and put axal grease on the tap . ran the tap through by hand to make sure not to make new threads . the tap did not shave any metal off just the carbon . so now fits like a glove again