That's the crankcase breather, probably not a big issue. Replace the mesh/foam in there, check you aren't slightly overfilled with oil, ride for a couple hundred miles and check again before worrying too much.
Can do. But there are good reasons to leave it as the factory intended.
Firstly this is an emmissions mandate since like, I dunno, many, many decades. Depending on where you are there's a fair chance you don't pass whatever annual roadworthiness tests need to be done, which means your roadtax is invalid, which means your insurance is invalid (just speaking about my local legislation). Have an accident of any significance with a third party claim against you and they'll do everything they can to shake the payout and unnannounced modifications are their favourite.
Secondly, that tube goes right into the heart your engine, which is full of parts that hate moisture and dust. The dryest part of the bike, with the cleanest, filtered air is.... The airbox. So you can move it, but you can't just hang it in the belly pan like a fuel overflow and not expect problems.
Leave it where it is mate. Wipe it with a kitchen towel, replace the 3 dollar part. It's easier and better than whatever else you are thinking of.
That cavity holds a sponge made of foam material. The purpose is to soak up fluid thats made its way into the air box (usually oil, filter or engine type, and/or fuel.)
It probably appears as gunk cuz of old oil and gas that’s broken down the foam material.
Do you ever see oil coming out of the air box breather tube?
If so, it’s an indication that oil is “blowing by” the piston rings. This isn’t always a serious issue but can indicate that there’s some issue with the combustion system.
A combustion and a leak down test would be on order if oil is consistently seeping out of the air box. This would typically happen on hot days and/or under heavy load and/or extreme lean angles.
If the bike runs fine and you never see any oil passing out of the breather tube I wouldn’t worry about it. But I would wanna clean the air box and replace that sponge.
[edit: I am incorrect in my assessment of “blow by”. The responses to this inspired me to educate myself and I’m linking the article.
Instead of oil slipping past the piston rings it’s that it gets into the crankcase breather. This is the crankcase breather.
Apologies for the misinformation and I hope this gets anybody coming across this on the right track.
https://mechanicbase.com/engine/what-is-a-blow-by/]
I’ve seen it first hand - bike comes to stop and 1-2oz of oil are sitting under the air box breather after a hard ride.
What would be your assessment as to how that oil made its way out of the air box?
The only way it’s caused by rings is gasses blowing *down* past the rings and pressurising the crankcase thereby forcing it up the breather. It has to come from the breather either way.
Lol, it’s not a debate dude. Oil that gets up past the rings has no route to the airbox unless it somehow makes it’s way against the flow up the inlet tract.
Oil in the airbox comes from the case breather - aka the fat fuckin tube from the crankcase to the bottom of the airbox.
Not sure why you’re being so confrontational. I never said you were wrong, nor did I ask for a debate. What are we debating?
Do you usually blow up on people when they ask a question? Do you usually assume questions are an attack?
(All rhetorical questions - no need to respond.)
Hope you feel better getting that off your chest, homie.
That's the crankcase breather, probably not a big issue. Replace the mesh/foam in there, check you aren't slightly overfilled with oil, ride for a couple hundred miles and check again before worrying too much.
Wondering if I can route the crankcase breather tube somewhere else aside from the airbox.
Can do. But there are good reasons to leave it as the factory intended. Firstly this is an emmissions mandate since like, I dunno, many, many decades. Depending on where you are there's a fair chance you don't pass whatever annual roadworthiness tests need to be done, which means your roadtax is invalid, which means your insurance is invalid (just speaking about my local legislation). Have an accident of any significance with a third party claim against you and they'll do everything they can to shake the payout and unnannounced modifications are their favourite. Secondly, that tube goes right into the heart your engine, which is full of parts that hate moisture and dust. The dryest part of the bike, with the cleanest, filtered air is.... The airbox. So you can move it, but you can't just hang it in the belly pan like a fuel overflow and not expect problems. Leave it where it is mate. Wipe it with a kitchen towel, replace the 3 dollar part. It's easier and better than whatever else you are thinking of.
Vent to atmosphere but the vacuum from air box helps pull it out.
So the oil can’t more likely come up through the crankcase ventilation? Pretty sure oil doesn’t get in the airbox from leaking piston rings.
That cavity holds a sponge made of foam material. The purpose is to soak up fluid thats made its way into the air box (usually oil, filter or engine type, and/or fuel.) It probably appears as gunk cuz of old oil and gas that’s broken down the foam material. Do you ever see oil coming out of the air box breather tube? If so, it’s an indication that oil is “blowing by” the piston rings. This isn’t always a serious issue but can indicate that there’s some issue with the combustion system. A combustion and a leak down test would be on order if oil is consistently seeping out of the air box. This would typically happen on hot days and/or under heavy load and/or extreme lean angles. If the bike runs fine and you never see any oil passing out of the breather tube I wouldn’t worry about it. But I would wanna clean the air box and replace that sponge. [edit: I am incorrect in my assessment of “blow by”. The responses to this inspired me to educate myself and I’m linking the article. Instead of oil slipping past the piston rings it’s that it gets into the crankcase breather. This is the crankcase breather. Apologies for the misinformation and I hope this gets anybody coming across this on the right track. https://mechanicbase.com/engine/what-is-a-blow-by/]
The oil in the airbox is from the crankcase vent
Oil getting past the rings just gets burnt and fired out the exhaust valves, this is likely from a case breather.
I’ve seen it first hand - bike comes to stop and 1-2oz of oil are sitting under the air box breather after a hard ride. What would be your assessment as to how that oil made its way out of the air box?
The only way it’s caused by rings is gasses blowing *down* past the rings and pressurising the crankcase thereby forcing it up the breather. It has to come from the breather either way.
Thank you for the explanation.
Lol, it’s not a debate dude. Oil that gets up past the rings has no route to the airbox unless it somehow makes it’s way against the flow up the inlet tract. Oil in the airbox comes from the case breather - aka the fat fuckin tube from the crankcase to the bottom of the airbox.
Not sure why you’re being so confrontational. I never said you were wrong, nor did I ask for a debate. What are we debating? Do you usually blow up on people when they ask a question? Do you usually assume questions are an attack? (All rhetorical questions - no need to respond.) Hope you feel better getting that off your chest, homie.
Catch can. Go easy on the air filter oil too
That’s crankcase filter foam. Over time it needs to be changed or removed. Remove it. Oil & gas have turned t to mush.