XJ crankcase pressure?

[Uncle Fester]

XJ600 Diversion. Every once in a while it chucks a large amount of oil out the drain tube in the bottom of the air box. I mean most of the sump contents in a few miles.

Then it doesn't use a drop of oil for weeks.

I have heard of another XJ600 div doing the same. Why do they do this and how do I stop it doing it?

Edited by Uncle Fester on Monday 7th January 20:38

[bimsb6]

check if the engine has a breather out of the cylinder head and check its not getting pinched shut .

[Benni]

If you are riding the bike under the -now- freezing conditions :
maybe the mix of oil & condensed water,
that comes out of the crankcase and into the breather pipe,
gets frozen, and the breather pipe gets clogged up sometimes ?

€dit for cranked spelling

Edited by Benni on Monday 7th January 22:44

[Uncle Fester]

I thought blocked breather pipe too.
But it seems clear, besides the oil is traveling up that pipe to get into the airbox.
The problem happens summertime too, not just cold weather. So I doubt its freezing.
Bikes done about 25k miles

[bimsb6]

Uncle Fester said:

I thought blocked breather pipe too.
But it seems clear, besides the oil is traveling up that pipe to get into the airbox.
The problem happens summertime too, not just cold weather. So I doubt its freezing.
Bikes done about 25k miles

if thats the case is there a crankcase breather thats getting blocked they usually appear behind the cylinder block under the carbs .

[tfm]

I had the same problem with my 900, which was caused by a loose crankcase breather pipe allowing oil to blow up the rocker cover breather.
Check all your hoses.