Good Trail Plug for 400ex

[hushmoons]

What would be a good plug for where i ride its alot of twisting turning trails mudholes hills and very few oppurtunity to open 'er up seems i foul plugs , another problem is water sees if i get her wet she runs bad. any ideas???? 2001 Stock 400EX

[GPracer2500]

NGK DPR8Z is the standard plug and the appropriate plug for most conditions. The alternative plug is a DPR9Z which is a colder plug--a colder plug will be MORE prone to fouling so it doesn't sound like that's what you want.

I suppose you could run a DPR7Z but I WOULD NOT reccomend it. You run the risk of overheating the plug, pre-igniting, and destroying your engine.

If you're fouling plugs than your carburator jetting is off. That could either be a direct result of having the wrong jets installed or it could be as simple as a clogged air filter or some other intake obstruction (mud in the snorkel??). Is your choke operating normally(?)--that's another thing to check. Has the quad ever been jetted? If so, what size jet are in it? Do you ride at very high altitudes?