400 Ex Clicking Noise

Brand New 2001 400EX (1 month old - past break in period)makes a singular clicking noise every time you rev it up after engine reaches operating temperature. Talked to several service reps at dealer, head of service, GM of store and Honda Corp - none of them have heard of this problem before. It does not make this noise all the time only when the engine is hot and you have been through all the gears. Dealer serviced 3 times already!!! Did the following work - valves have been adjusted, dealer replaced spark plug,cam & compensator, starter clutch, piston pin, 2 different gears, clutch outer casing, 3 gaskets and a bunch of bearings. Run 91 octane gas only (highest I can buy here in Colorado other than racing gas)... Almost sounds like someone is tapping the engine case with a screwdriver. Can't pinpoint exactly where its coming from but you can hear the noise over the engine.

[Guy400]

Is the engine broken in yet? After break-in you should definitely check valve lash as they may need adjusted. If the sound is real bad it could be a rocker arm that's a little loose. I know my cousin's 400EX makes a little tapping sound when you rev it up. I may be mistaken but I think that sound is a trademark of this engine. I've heard of numerous other owners talking of it.

sounds like your valves need adjusting

[4punksdad]

have you tried changing your spark plug? Maybe the "knock" you hear is unburned fuel. If it were valve noise it would not be a singular "tap".

[Revin300EX]

Drain the gas tank and put some premium fuel in it... I bet it stops!

[Winged Warrior]

I have tried everthing i think? Took back to dealer after making noise (month old) they couldnt find nothing wrong .drain all gas try dif gas twice. New plugs ect ect. still makes this noise still bugs me ! :blah :grr

[Revin300EX]

Where exactly is it coming from? See if you can tell...

If you cant, go and get one of those mechanics stethoscopes, and start poking around with it.

If we know where its coming from, we can tell you what it is...

[Guy400]

You don't need to go buy an automotive stethoscope, you already got one at your house. Take a broom handle and unscrew it from the sweep. Touch one end on various parts of the motor while you cup your hand around the opposite end of the broom handle and your ear. Voila, a free stethoscope! That's an old drag racer trick.

[400exRacerX]

put super "93" octane gas in there, it sounds almost like its pinging to me

[Revin300EX]

And if you cant find the problem, you can always beat it with the stick! Thats what I do!