A friend of mine has a 99 400EX with Big Gunn Exhaust, K&N, Jetted.
We changed the oil about a month ago, poured in almost 2 qts. of Honda Gold and a new filter. Granted, it gets run pretty hard sometimes, but NOT abused.
We were tuning it up some and changing sprocket sizes on it the other day. I happened to check the oil level and it had NOTHING in it!!!!.. I wiped it off, re-checked it again... NOTHING!!.
I broke out the trusty KawiChem 10-30 and started pouring... ONE AND A HALF QUARTS LATER, it was in the safe zone!!!!!!!......
THIS bike does NOT smoke!!! It does NOT have any OIL LEAKS.... I thought maybe he got a little vertical and it dumped into the airbox, so I checked there.. NOTHING!!..
IS there some reason the 400EX is using so much oil?.. Is this Normal?.. What Oil is everybody else using in their 400EX engines? Where am I missing that the oil could be going?..
HELP!!..

 

What you did not say is when the last oil was added. What is the oil level now? How often have you checked/changed it?
Are their any wet oil spots on the bottom of the engine? Put the ex up on the grab bar and check it out, you might have lost it through a leaky seal.


oh, my bad, I did not see the first part where it says 2 months ago.

 

holy cow, sounds like a leak to me, I have never had any of my hondas use a drop of oil. I would check around the oil res for leaks or something,

 

We changed the oil about a month ago.. And its REALLY shouldn't have used a significant amount of oil since then....
He keeps the bike clean, and we've looked all over it, checked the back of his truck, checked his carport.. NOTHING...
We are quickly starting to think that its getting burnt, just not enough, fast enough to show up as smoke out the pipe... ?????... (Im reachin on that one)
He makes 80 MPH blast' down the highway at night, passing cars that are cruising at 70 MPH... I'm wondering if when pinned at W.O.T. in top gear for 3-4 miles might be pushing oil?...

 

That just might be pushing the oil

 

Hmm, Hondas rev limiters are designed to stop overrevving on a shift point, 3-4 miles of countiouns red line RPM would still cause damage even though the stock revlimiter allows it to go that far, I always cruse 10MPH below top speed. Have him stop the extended redline rideing and see if the oil lasts longer. If he wants to go fast get a bigger front sprocket

 

While I've tried repeatedly to get him to stop blasting it down the highway.... ITS LIKE TELLING A CRACK HEAD TO STOP SMOKIN CRACKROCK!!!.. The accelleration rate and top speed of that thing is ADDICTIVE... So much so, that if Honda would build a 4x4 version with reverse, the manual clutch, switchable 2/4 option.. I'd sell BOTH Polarises I own and go buy two of them!!!...
Anyway, back to the oil thing... I think we are gonna switch to either Klotz or Red-Line oil and see if that helps... If not, the top end is coming off for an RCR 430cc Kit... That oughta fix it!!!

 

What weight oil are you using? I do that same thing your buddy does. I drive wide open for miles upon miles at times. If I use 10/40, then every week or two I have to add more oil. The solution is running thicker oil. I would try 15/50, or 20/50. I like 20/50 myself. In the winter I use 10/40, but in the summer I use 20/50. Try that and let us know how it works out.

 

I'm guessing your "missing" oil stems from the fact that you checked the oil on a cold engine. The manual specifically states that you need to run the engine for at least 5 minutes, then shut off the engine and check after 2 minutes of sitting.

I assume if the motor sits long enough (cold) the oil sneaks back to the case via gravity, thereby giving you a low reading in the external oil tank.

I did the exact same thing about a week ago and some of the folks here helped me out with it.

Needless to say, you need to check it properly and empty out some of that oil if its high. When I checked mine, I had oil at the top of the dipstick, way too much!

Hope this helps.

 

I'll give that a try... Like I say, its NOT smoking that we can tell.. Its got to be going somewhere...
Although, when I checked it, we had jsut got thru blasting it down the road.. It had sat about 5-10 minutes... But, I will try what you are suggesting.. Thanks!!!