I have a 400ex with only two tanks of gas through it and at times it makes these wierd noises on excelleration in the engine. Kinda like a chirp type ping only once each excelleration and not always. And it only seems to do it after it gets warmed up.
Any help here before the warranty runs out wouold be great,
(the dealer says they all do it) I dont believe them thou!

 

One thing that comes to mind--I had a similar squeak/chirp on my 400EX, when I mashed the throttle.

Squeaks and rattles annoy the crap out of me, whether in my car, or on my quad. Anyways, this squeak wound up being the bolt & rubber grommet that holds the exhaust to the subframe. Try this to see if you are having the same squeak: put on some gloves, put the bike in neutral, stand beside it, and rev the engine until the squeak starts, then hold the exaust/muffler with one hand (keeping it from vibrating at all) with the other hand still on the throttle...see if the squeak stops.

If it does stop, loosen the bolt, and shoot all kinds of white lithium grease all around the rubber grommet, and retighten the bolt. This will stop the squeak for a long time, if not permanently.

It is MIND BOGGLING how many bolts have vibrated loose (I've had 6 bolts vibrate off mine), and how many squeaks the average 400EX has...so much for Honda quality. I had my 1992 250X for 8 years, and NEVER had a single problem with it.