mmm....

[Nelly]

Never heard this one before and sort of hoping that someone on here may know what is happening,
Friend of mine has a fairly old bike that suddenly, without warning started throwing what smelt like fuel but looked like oil out of the air filter casing. Not much detail other than that as i havent seen it.
Sounds like a fairly serious thing to me. Anybody any ideas what it can be and whether is majorly serious? :question :question :question

[NiteW4tcher]

sounds weird to me............carb or injection?

[Sean.C]

Could be a blocked breather pipe

[Cemorah]

Sticking float in the Carburettor!

Most engine breathers run into the air box so there is always a bit of dirt and crud in there. If a float sticks fuel may back fill the air box and dissolve this pouring out looking like oil.

Remedy Remove carbs and service fit a fuel filter to stop crud getting under float needles

NB overflowing fuel can get to the crankcases open the crank case filler and sniff for petrol - if at all unsure change the oil & vent the crankcases for a day or more.

[470four]

Some bikes run the cylinder head breather pipe back into the airbox so that the bike burns its own engine fumes as an anti-pollution measure, rather than have then vent to the atmosphere... not too sure why hes getting fluid back thro there tho! Has he overfilled the bike with oil?

Most carb overflow tubes empty under the bike itself?

[Cemorah]

Oil from the engine should not smell of fuel.
Most carb overflow tubes empty under the bike itself? Granted
but they are very small brass tubes in an aluminium casting and rarely if ever get cleaned out.

This is a common problem with GPZ500' s and I have even had it happen on a GS125.

the consequences of heating up an engine which is partially full of petrol vapour may warrant checking this line of enquiry first!

[Jon_W]

It's probably an engine breather. A lot of them breath back into the airbox. Is it running on old oil???