Venture RS oil in air box

[204yamaha]

Hello there,
first time posting, sorry if I’ve posted in the wrong section.
Noticed oil dripping and took apart the airbox
There was a substantial amount of oil that came out of the reservoir when I removed the bigger 3/4” hose going into the airbox.
After disconnecting all the hoses I tried blowing into the port I circled in the photo. I couldn’t blow into.
I tried sucking on the port (the return line I believeit’s about a 1/4” tube on the underside)
it allowed me to but seemed very restricted.
Would this have anything to do with the excessive oil in that box?

The sealed reservoir inside the airbox, what is the make up of it? Is there a check valve of
Some Sort in there?

Any suggestions would be greatly appreciated.
Thanks guys
-Nick

 

[thrasher]

Oil does flow thru the air box and exits thru the smaller orifice in the bottom of the box. I know this because if the lower hose is not attached properly after reinstalling the airbox, oil will pour onto the ground once you start your machine. There is a chamber in the airbox, and sometimes if there is moisture in the box, it will freeze if it's really cold out, blocking the normal flow of oil. There are small amounts of oil residue that will accumulate in the box around the foam inserts in time. The oil in that cup looks contaminated with a lot of water giving it the milky colour. So I would suspect that something got frozen in there. Putting your sled somewhere warm for a day should thaw things out, and get the oil flowing properly.

 

[theCATman]

Oil does flow thru the air box and exits thru the smaller orifice in the bottom of the box. I know this because if the lower hose is not attached properly after reinstalling the airbox, oil will pour onto the ground once you start your machine. There is a chamber in the airbox, and sometimes if there is moisture in the box, it will freeze if it's really cold out, blocking the normal flow of oil. There are small amounts of oil residue that will accumulate in the box around the foam inserts in time. The oil in that cup looks contaminated with a lot of water giving it the milky colour. So I would suspect that something got frozen in there. Putting your sled somewhere warm for a day should thaw things out, and get the oil flowing properly.

Whoa, whoa, whoa here....


Oil DOES NOT, I repeat, DOES NOT flow through the airbox.

The hoses are for crankcase pressure evacuation/breather. Same as a gasoline powered car/truck/suv. Crankcase pressure vapors are exhausted back into the air intake tract where they are sucked in by the carbs or throttle bodies, and burned in the combustion process.

Now, what DOES happen with our beloved Yamaha 4s sleds IS THIS..... both the 3 & 4 cyls do it, but for whatever reason I don't know, the 3 cyl is VERY picky on its oil level. If it's overfull, it will puke oil into the airbox and this is the result. A few drops is normal, that's just parts of the vapors that didn't get sucked in & burned. A cupful like this, it's overfilled.

The oil level should be barely on/right at the bottom of the checkers on the stick WITHOUT the dipstick screwed into the tank. This is also AFTER the engine is started, and has idled for a few minutes, shut off, let it sit a few more minutes, then check for proper oil level.

 

[theCATman]

You are correct @thrasher that if the lines aren't hooked up properly it will pump oil out into the airbox resulting in a giant azz mess & possibly wreck the engine once it's starved of oil, but that's only because the vacuum lines & hoses aren't hooked up properly, oil definitely does not flow thru the airbox.

 

[thrasher]

Sorry, it doesn't flow thru the air portion of the box, but the sealed compartment/chamber on the right side of the airbox. It's not under much pressure or the lines would blow off. If you don't believe me, just don't connect the lower hose and see what happens. It is a breather for the crankcase, but some oil passes thru there.

 

[Stubbs]

Sorry, it doesn't flow thru the air portion of the box, but the sealed compartment/chamber on the right side of the airbox. It's not under much pressure or the lines would blow off. If you don't believe me, just don't connect the lower hose and see what happens. It is a breather for the crankcase, but some oil passes thru there.

This is 100% accurate with the 973 carbed motors, the 1050 fuelie motor does not utilize the airbox in this same way.