Engine Noise at idle

[coastie720]

Hello gents, newb here :D Im new to the 400ex, and was wondering if someone could explain this noise. At warm idle, the engine sounds like there is a pressure relief valve somewhere in there. Every couple seconds you will hear a slight 'blow by" noise. I also get it when im compression braking down a trail. Other than that it runs like a top. Thanks in advance for any help.

Chris

[tri5ron]

Chris,
Welcome to the forum, this does not sound normal.

At warm idle, you say this happens "every couple of seconds".
so am I to understand, that it does not make this sound at each compression stroke, at Idle,.....

But it DOES happen at each compression stroke while "engine braking" down a hill?

do you see any evidence of oil leaking around the head, or base of the cylinder?
How about the inside of the airbox, do you see any excessive oil in it?

Can you hold your hand near the cylinder at idle, and feel this blowby at the same time you hear it?

It might help some of the members here to help you out, if you tell us a little more about your bike.
Year, condition, previous maintaince routines, previous useage, any engine modifications, etc.

[coastie720]

Thanks for the quick reply! Its a 2003 400EX, Stock except for exhaust. I bought it used in good condition, the guy said he bought it for his wife (older couple) so I believe him :D .

Today, I checked the head and cylinder areas and no oil or anything. The only work I have done is an oil change with Mobil1 4T, and an EMGO filter. I also changed the spark plug at the same time. The noise is similar to (dont laugh) when you eat something sour, and you make that noise with ur tongue on the roof of your mouth. I know that explanation of the sound is gay, but thats all i could do. And it only happens when coming to a stop from high speed or compression braking. Thanks again for any help

[tri5ron]

Ok, first lets get one thing straight...

We like to laugh around here, and if you give us a reason to, we surely will.
HELL, most of the time, you don't even have to give us a reason ! We'll still laugh anyway,...
but your tounge sucking thing,
is CERTAINLY an original description method, and I'm cracking up! :devil: (Thanks for the laugh) :D


Now, you say that you are confident that it is a good condition, well maintained quad,
ridden only on warm and dry Sundays,
to and from Church,
by a Little ol' Lady from Pasadena,
for carrying her fruit salad,
to the afternoon social....

OK, that's a good thing I suppose,
but was she the original owner?
OR,.....

Did she buy it from a washed up, wannabe, appliance repair school drop-out, armed with a pipewrench, two rocks, and a hammer, who had aspirations, of becoming the next legendary, Supercross hero, and comic book action figure?

(now don't laugh, just answer the question) ;)

[coastie720]

Im not sure if she went to church, but everything else is correct :p I cant figure it out. Its not leaking and it runs awesome. Maybe its me.........

[tri5ron]

400ex's are notoriously noisey engines.
Especially to the unfamiliar , uninitiated , new owner.

what is interesting here though, is your description of the sound.
you describe it as a sucking, blowby type sound,
and most new guys ask about a "ratteling", "tapping", "clattering", "clicking",or "knocking" type sound,...
normally originating from the valve cover, and asking if we think the valves need to be adjusted.

The usual answer to that is, if the quad has not been abused, or over-revved, and decently maintained, and has the proper level of fresh oil, ...chances are your just not used to the normal sounds of your beloved 'Fo-Hundy.

BUT, that does raise a couple of other questions.
when you changed the oil,... Did you drain BOTH the engine AND the oil tank? (there IS 2 drain plugs ya' know).
Also, are you sure that you did install the filter in the proper direction?

and did you measure the oil that you put back in, or did you just read what the dipstick said, without turning the engine over, and re-checking it ?
(keep in mind, this is a "Dry-Sumped" engine)

[coastie720]

I drained both the case and the oil tank. I cleaned the strainer, and put the oil filter in the right way. It had the THIS SIDE OUT stamped on the metal :p I guess ill just live with it until it becomes painfully apparent.....which i doubt. Thanks for all the help though.

Chris

[tri5ron]

Originally posted by coastie720
I drained both the case and the oil tank. I cleaned the strainer, and put the oil filter in the right way. It had the THIS SIDE OUT stamped on the metal :p I guess ill just live with it until it becomes painfully apparent.....which i doubt. Thanks for all the help though.

Chris No problem,
that's what we try to do around here, (as well as pick on each other a bit for entertainment).
I'd say that if you feel it's running strong, and are not too alarmed by any sounds, your probably just still getting used to it.

It might be a good idea to just give all the intake bolts and exhaust bolts a test snug, to check for any thing loose.

Are you sure it a "Air Leaking" type sound ?,
as opposed to a "ticking/clicking" type sound?

also what type/brand of exhaust does it have?
Full aftermarket header and muffler ?
Stock header w/ aftermarket slip-on muffler?

do you have your airbox lid on, or removed?

Has it been rejetted?