Oil in Airbox

[MongoE9]

While performing some routine maintenance on my bike, I removed both sides of the (what I call airbox) under the tank, that connects the hose from the airfilters into the carbs and found that they were wet with oil inside them. The foam gaskets that mount the two sides together were pretty wet with oil as well. Is this an issue or normal occurence? At first I was thinking it was fuel since they open to the carbs, but it was definitely oil. Where is that coming from? They were not dripping wet and there was more on the left side than right, but it was enough to get my attention.

Thanks

Mongo

[Sideoftheroad]

Check the oil level window towards the bottom right side of the bike. Should be between the 2 marks just a hair above the middle point. Anything above that will start to puke oil. Some (including myself) had actually mistaken it for a failed shock.

[Guest]

The oil builds up there due to the extreme lean of the bike on its side stand. Also, overfilling the oil will cause it too. The simple remedy is to add about .5 qt less when you change your oil. The manual calls for 3.9 qts of oil. Add only 3.5 and you should be good to go. When level, with the 3.5 qts the oil level in the window will be about halfway up the sight glass. Any higher and you will run into this issue again.

[Guest oldroadstar]

The oil you see is coming from the crank case vent tube that is between the two banks of carbs. I removed the hose form the box where you see the oil and ran a longer tube down and out under the bike. No more oil. Yes, over filling will cause the oil you see but you will still get some just because it is venting from the engine.

[allwx]

You'll always have a trace of oil in there no matter how low you run your oil level between the two lines on the sight glass. The crankcase vents into the airbox. The air carries a very small amount of oil mist in it, and some of the oil collects in there while some of it is inhaled by the motor and burned. I think the oil there is a good thing, because it helps to trap dust particles that make it past the filters, and enter through other tiny openings in the long airway from the front of the bike to the carbs. Some of it will leak out of the left side of the airbox while the bike is parked on its sidestand. No big deal.

[BuddyRich]

Yep, There will always be some oil in the air boxes due to venting. Much like a PVC valve in the old air cleaners back in the 70's and 80's

[MongoE9]

THanks to all for the reply. That is very valuable info.

Mongo