oil leak

[shiftyxr]

hi peeps,

i've got an 85 GPZ600R and it's leaking oil from the crankcase vent. it's quite random as to when it leaks, i've ridden 100k's and no leak but then it will leak after a 2k ride to the shops.
it'll leak sometimes at high revs but other times it wont.
it'll leak sometimes at low revs but other times it wont.

i've checked the oil level and it seems fine and i've not noticed any cross contamination from oil leaking into the cooling system or vice versa.

any help would be greatly appreciated.

[jefflthomas]

you've got an open crankcase vent?...no hose?

[shiftyxr]

there is a hose on the vent, the oil runs out the end of the hose n down the outside of the front sprocket cover