2000 400ex noise at speed

[StreetLegalEX]

Well, I just bought a 400ex about a week ago.
It has a new piston and a couple of new bearings in the engine.

The machine runs absolutely great (I have been a little easy for the bike because the new piston has to be broken-in).

Now I'm gradually giving it some more throttle.
But when I go down the road at speed and high-rpm I hear a rattle noise in the engine. (I had a Blaster before so not really used to 4stroke, maybe this is normal?)

When stand-still it sounds normal, doesn't even rattle when I rev the engine. It's only at high speeds and high rpms.

At first I thought it might be the chain rollers, but when I pull the clutch the rattling is gone, so it has to be in the engine.

Any clues?

Some extra info:

The bike hadn't been run for a while when I bought it
I use 98 octane fuel

mine does the exact same thing! I thing its the chain rolling really fast on the roller pins. someone correct me How is your EX street legal? what state you in? Can Tennessee quads be legal?

[StreetLegalEX]

Yeah, but when I pull the clutch the noise is gone, so it can't be the chain because my speed doesn't change when pulling the clutch.

P.S. I live in Belgium, where quads can be street-legal. (getting my license-plate this week I hope!)

Hell, whe have street-legal Banshee's, Raptors, Z400, everything you can possibly think of! :D

oh, thats cool. i seriously think its the chain b/c thats exact same thing mine does

[Mr_Bub400ex]

if it stops when u pull in your clutch lever its the clutch lever itself. well it was on mine. it used to be a rattling noise on the road when it got up to higher RPM and the bike vibrated. it made the lever move in the huge stock lever housing thing. get a p-brake block off and a new lever and perch and it will fix the annoying sound

[BadA$$440]

sounds like you might have to adjust your valves, does itsound like a fast ticking noise? if so, its your valves. Tighten them up a little

[cals400ex]

where is the noise coming from? sometimes the heat shield comes loose on the header. also, it could have something to do with the chain. when you are going a constant speed or accelerating, you have some stress on the chain. when you pull in the clutch, you don't have stress on the chain. i would just go around the bike and tighten every bolt you can see. also, my chain rubs on my case saver behind the chain guard every once in a while.

[StreetLegalEX]

Thanks for all your responses, I will check them all today. Will keep you posted!

[StreetLegalEX]

Rode it again today (for about an hour and a half) at various speeds, and I think its just normal valve noise, that all 4strokes have. I think it's possibly because I am used to the Blaster that I noticed the sound.

All I can say is that I really love my EX and hope to spend many hours of riding fun with her. :cool: