I own a 400 EX and recently removed the spark plug. It stayed tight all the way until removed and when installing the new plug it after the first turn it got to tight to turn by hand. I have checked and doubled checked to make sure that I have not cross-threaded the plug. I have also inspected the plug for burrs on the threads. I even tried a different plug and got the same results. Does anyone have any suggestions on what could be causing my tight plug problem?

Thanks
David[img]i/expressions/face-icon-small-frown.gif[/img]

 

Putting a plug in the 400EX can be a bear. You really have to take your time and make sure it is at just the right angle to go in right.

 

putting the plug in is a pain. my 400 is the same way it gets tight real quick. i use my plug wrench and wiggle it around until it is all the way tight, never had any problems with it.[img]i/expressions/face-icon-small-smile.gif[/img][img]i/expressions/face-icon-small-wink.gif[/img][img]i/expressions/face-icon-small-sad.gif[/img]

 

mine is about the opposite, it takes 3 turns from all the way tight, then i can do it by hand

 

That is the way this one used to be but not anymore. The bike is also hard to start in cold weather. I guess a trip to the repair shop is in order. Planning a trip to Little Sahara and need to be in good working order.[img]i/expressions/face-icon-small-happy.gif[/img]

 

A 42 pilot jet will solve the cold weather starting problem.