2005 Kx250f crankcase vent hose spitting oil

Hi, I have just had my motor entirley rebuild by a very reputable mechanic. When i bought the bike it was puking oil out of the vent hose horribly, it had something clogging the oil sump screen. I spent 1600 bucks all in all. Brand new cylinder head, all new valves, crank bearings and all new gaskets. Also whoever had it before me used epoxy/ bondo to fill up a hole in the carburetor, so i got a new carburetor to. I know the engine is alright now. Heres the deal: I can ride the bike for 3 hours on the track. then when i roll into the pit and shut the bike off, i can look down under the bike and it just drips a tiny bit, just tiny little drops of oil out of the crank case vent hose, it doesnt puke it out. and I think it only does it when i stop the bike, What could be causing this? :confused:

did you measure the oil when you put it in or just fill it up to the sight glass? that could be one problem. how much does it drip? one or two drops, or does it keep dripping?

I just fill it up to the sight glass, I fill it right to the half way mark. It stops dripping. it harldy drips just a little bit comes out but still, its not right.

I had that problem and then i started measuring the exact amount of oil recommended by Kawi and it was fine. I think filling it up to the sight glass was putting too much in. Really, if just a few drips come out i wouldn't be "too" worried, as i'm sure it's really shaking in there and some might manage to find its way out.

thanks guys, ill try to get the right amount in there

ive always just filled to the sight glass, but if it is dripping out it could just be finding its way out a little bit, most of the time it will drip cause of pressure, let it do its drip and it will probably stop, once it gets rid of the extra oil it will be good

Greco, did you know filling to the sightglass is generaly off by alot?

Oil has a high viscosity compared to water. When you fill it, it takes a long time to dispearse to other areas ect? You also must realise that having the bike not being perfectly level will cause fluctionations???

Me, I think its hella easier to just drain both sides of the cases and filter then mesure out 2 bottles of oil to 1.35ltrs poor into and forget..

If you had one mesuring beeker that does more then 1.5ltrs would make it even more easier.

Atleast with the new 09s they take less then a ltr to fill. WOOT, err well if I buy one. Haha gotta sell my 05 first.

yea exactly, when my bike is on the stand people are like "yo dude your low" and im like *** dude? the tire is like 4 inches off the ground smart guy. anywho my bike is spittin it out like crazy now too, ima go fill it up to the manual specification

hopefully it stops

I went through the same thing when I put a new piston and rings. Turns out the ring gaps weren't lines up the way they should be (90 degrees out from one another worked best), or weren't seating properly. This lets cylinder pressure escape into the crankcase, pressurizing the whole mess and blows oil out the overflow. Damn 4 strokes!! I drained and checked my oil levels everyway imaginable, and it didn't stop until I tore the topend down again and rebiult. No more problems! Hopefully not your problem, but if it doesn't stop......

Greco, did you know filling to the sightglass is generaly off by alot?

Oil has a high viscosity compared to water. When you fill it, it takes a long time to dispearse to other areas ect? You also must realise that having the bike not being perfectly level will cause fluctionations???

Me, I think its hella easier to just drain both sides of the cases and filter then mesure out 2 bottles of oil to 1.35ltrs poor into and forget..

If you had one mesuring beeker that does more then 1.5ltrs would make it even more easier.

Atleast with the new 09s they take less then a ltr to fill. WOOT, err well if I buy one. Haha gotta sell my 05 first.

I dont think they would bother with manufacturing a sight glass into the cover (which im sure cost a pretty penny compared to not having it) if it didnt do anything...If you take your bike to a shop to get an oil change they use the sight glass to fill in the right amount...its better to overfill than to underfill...if it still pukes it out after filling the proper amount it could be the rings not seating or improper ring stagger like bikebum said...

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