Draining oil from Airbox drain hose. Frequent Oil accumulated.

[zirconxi_imp]

Hi all,

I can't find any info around so just going to start a new thread on this. I am wondering how frequent you guys have to drain oil trapped in the Airbox drain hose? I notice that for my bike, i need to drain it about everytime after i have ridden any single day trip above 500km. But if i rode short distant trip, its not required even after i rode 2000km (lots of short trip over a long period of time). I believe those oil are from the hose connecting cylinder head cover and the airbox. and the inner part of airbox is coated with oil because of this. I am wondering if its ok to connect this hose to another capture device instead of going into airbox....

[max]

Zirconxi i tip mine out about twice per year or so, and take the whole contraption off including the elbow, not very often but good to find the difference between long and short trips.

The top breatherhose re-cycles the unburnt fuel mixture that escapes past the piston rings during the compression stroke and is beiing sucked up by the airbox under pressure, re-introduced to the engine etc.
also the combusted ( with a light carbon content ) gas that escapes past the rings is re-introduced in the same way, it is called positive crankcase pressure and all engines have it.

So rather that venting this gas mixture to the outside world they "spool" it through the engine so parts of it get re-ignited and produces an overall cleaner exhaust emission and slightly better fuel economy.

As a byproduct of this gas some oil escapes from the crankcase in the mixture and if not collected would build up in the airbox and eventually come out at an inconvenient time/place (on your garage floor ), however a bit of oil in the airbox is not a bad ting as long as the owner empties the clear hose on inspection, on the plus side if the oil mist travels past the throttle body it may actually lubricate the moving parts inside and thus provide the owner with even more reliable life of the engine ( at this stage the fuel has not mixed with the air and oil laden mist can be your friend.

Don't just remove the little hose as this would introduce dust and everything else that fits in the small opening unfiltered straight to the engine.

Much more input of other members is helpful and you make an interesting point and yes, i have stuck a camera inside the airbox and got some shots of the oil film.

[the Ferret]

couple times a year here too. You could probably get some out after every decent ride. I just did about 1600 miles to the CB rally and back and did't even check it. I will next time I'm in the garage.

[GoldOxide_imp]

When the CB was new, the air box/drain hose experienced some emission. Subsequent checks have been dry. Just keep checking as part of routine maintenance.

[Cormanus]

Mine seems to fill frequently.

[dave]

I've drained mine once in five years, and 23,000 miles. Maybe the warmer climate in San Diego has something to do with it accumulating fluid?

[LakeWylieJoe_imp]

I've got 26,000mi on mine and I find it only puts oil in that hose if the oil level in the crankcase is right at the full mark or slightly above when parked on the centerstand. I did a 2,000mi ride to San Diego and back and saw no accumulation with the oil level about 1mm below the upper fill mark on the window.

[Pauley]

I check mine every few months. Had some liquid in there a few times when the bike was new. Nothing more for the past few years.

[jimgl3_imp]

huh? do what?

[GoldOxide_imp]

huh? do what?

Understood J3. I think I last checked in 2015.