Hi folks

just come back to motorcycling after 15year break. Iam running a 1989 xj600 pre diversion it has been running fine until i got some dirty fuel (water and sludge)I have cleaned the carbs down now the bike will not idle runs fine when reved but is blowing petrol back into air filter. petrol appears to be a browny colour looks like oil mixed with the petrol?

where do i start is it the carbs or engine problem.

Petrol tank has been emptied and flushed out with clean petrol inline filter fitted

I had a similar problem with my xj600, I Didn't have an idle problem but I was getting oil leaking from the air filter drain, when I opened the air box it contained light brown sludgy oil and a now knackered brand new K&N air filter

On the bottom of your Air box there is a little hole that lines up with the center of the air filter, on the underside I have a little pipe that does not connect to anything (clear about an inch long) when I put the box back on the pipe got bent over blocking the hole, I can only assume that the hole is there to stop a vacuum forming inside the Air box or some other technical reason that only a well trained grease monkey would understand.

Long story short, unblock little hole, oil stopped coming out.

Hope this helps.