400ex spark plug question

[gopeddin400EX]

I went to change my plug on my new bike well new to me its used and the spark plug is a DPR8Z and I hear the one I should be using is a DPR8 is that huring anything that I had that one in there? and it wasnt a browinish color it was like black and sooty

[speedy400]

I dont know much about the extra"Z" on that sparkplug but I can tell you the black sooty stuff is excess carbon build up from being rich on your jetting.-darren

[cals400ex]

the stock plug is a ngk drp8z. that is the one your suppose to use. where was it black at on the plug? what size jets are you using in the carb?

[quadrider400]

Originally posted by cals400ex
the stock plug is a ngk drp8z. that is the one your suppose to use. where was it black at on the plug? what size jets are you using in the carb?

One addition if you are in the sand or "high rev conditions" Honda suggests a DRP9Z if you are in the woods then the 8 is the way to go.....

And remember a lot to rich is better than a little to lean...:p

[EXerHonda400]

ya you are a little rich, but o well. anyway i am not an NGK fan so i buy Champion Powersport 8809. I have had my best results using them and they are an identical stock replacement.