Odd engine noise

[MidnightBlade]

My 05 has a whine almost like a supercharger, it was just broke in last summer so there aren't many hours on it. It is stock bore, stock cam, stock crank, basically only things I've done is exhaust and filter. The quad has done this since I bought it and I never really worried about it but now curiosity is getting the best of me

Here's a vid 400EX engine noise (http://www.youtube.com/watch?v=zKtltUqtDSk)

[NacsMXer]

Mine has done that a few times after the engine has gotten hot. It sounds like the sound of oil being pumped through the engine to me. I have heard other engines do this as well. I'm not sure if it's normal at all but it's never hurt anything on my motor.

[CJM]

Take your hand and place it over the end of the exhaust-hear air hissing out you have an exhaust leak. Always a possibility but to me it sounds engine related.

Could be timing chain related or perhaps something is contacting (metal to metal) and bouncing around at a vibration from the engine.

Take a long screwdriver and put the tip on the engine and the other plastic end to your ear-you can sometimes pinpoint a noise this way.

Have you ever had the engine apart?

[MidnightBlade]

No, never had the engine apart.

Also, it only does it when cold, once it is warmed up for 5-10 min it goes away completely. :confused:

[4HundredEX]

I have the same exact noise in mine too. Never have been able to figure it out. Only does it when its cold...goes away after 5 or so minutes. Goes away and it runs perfectly.

[CJM]

What weight oil are you using and does it happen only when its cold outside?

[4HundredEX]

Originally posted by CJM
What weight oil are you using and does it happen only when its cold outside?

I have been using Honda GN4 in mine. It happens when the engine is cold, not weather related on mine.

[MidnightBlade]

I run 15w-40 Shell Rotella

Mine does it anytime I haven't started it for a few days or the engine is cold. Temperature doesn't make a difference, it was about 95* or so in the video, does it in the dead of winter too.

[kt1148]

Sounds like an air leak to me. Could be intake or exhaust, that's what I would check.

[MidnightBlade]

I've checked, and double checked the intake for leaks. The exhaust I don't really worry too much about, my header bolts are tight and thats about all I worry about.

[kt1148]

Just a thought, my slip-on doesn't have a clamp, it just slips over the header. Maybe it's a small leak there till it warms up, not sure how your hmf connects

[CJM]

Betcha its an exhaust leak then.

Id worry if you have a leak-you got a leak it will cause a lean condition in some cases which can be bad.

[mittman]

I know mine has that noise to it but its not that loud at least I dont think it is. Ill have to see if it does it when I put it back together.

[ridehonda400ex]

Mine does it too, I never really worried about it, i will when something goes wrong tho lol

[NacsMXer]

Don't think it's an exhaust leak guys. If you heard it in person it's coming from inside the motor, almost in the tranny area. Like I said, it sounds a lot like an oil pressure sound to me. I can't explain why it does it though, it has always gone away.

Many crotch rockets have this whirring sound constantly as the motor is running, it is the same thing.

[bergoff]

Mine sounds the same and its stock for now. Also my xr650l and xr600r made that same sound I never worried about it. Both xrs had pipes and carb mods with cams and it was always making the same sound.

[4HundredEX]

[QUOTE]Originally posted by NacsMXer
[B]Don't think it's an exhaust leak guys. If you heard it in person it's coming from inside the motor, almost in the tranny area. Like I said, it sounds a lot like an oil pressure sound to me. I can't explain why it does it though, it has always gone away.

I concur... Sounds the loudest on the clutch side of mine. It goes away after a few minutes, so I havent really worried about it. I will check the carb and header for looseness, but it will be monday before I get to where I keep it stored.

[MidnightBlade]

Originally posted by kt1148
Just a thought, my slip-on doesn't have a clamp, it just slips over the header. Maybe it's a small leak there till it warms up, not sure how your hmf connects They have a clamp but I never tightened it because I have to switch between stock or HMF depending on where I'm riding.

[MidnightBlade]

Originally posted by kt1148
Just a thought, my slip-on doesn't have a clamp, it just slips over the header. Maybe it's a small leak there till it warms up, not sure how your hmf connects They have a clamp but I never tightened it because I have to switch between stock or HMF depending on where I'm riding.