Gas in Airbox/crankcase question

You know, we get on average 1 question a week on this subject, from someone suffering it.

But, you know, out of all the people who ask questions about this, coz they are suffering from it, have not asked (not that I've seen, anyway) what I thought might be the obvious question to ask about this, so I'm going to ask the question on their behalf, and also because I'd like to know the answer myself. Here's the question:

Why does the stuck float syndrom (or any other carb problem) cause fuel to build up enough to get into the combustion chamber, and down into the crankcase, polluting the oil and causing the problems that go with it, BUT does NOT escape from the obvious place - The overflow pipes fitted to the carbs? At the moment, I can only think of one thing that might cause that to happen, and that is the pipes are blocked with dirt.

Over to you BigFitz, Rick, or any of the gods on here can you shine any light on to this subject?

 

earlier models don't have the overflow pipes

 

A LOT of models don't have overflow pipes; plus the "overflow system" can be overwhelmed by too large of a volume of gas.

 

I didn't realise a lot of models don't have overflow pipes, I wrongly assumed that because my bike has them, that all the XJ's had them. Thanks for putting me straight on that Mav and Fitz.

 

Great to know. I just had my carbs off for the first time and didn't know what those were. I feel better already.

 

There you go, me being inquisitive has helped some one already, job done

 

I've learned a ton just by reading other riders questions and answers. I look at the forums every day just for that purpose. I have a Honda Shadow that is almost maintenance free, and when I bought the XJ700N, my "sports car", I had no idea what I was getting into maintenance wise. But even thought I love working on my machines, I would have been lost without this site and all the information from the few riders that seem to know everything about the bikes. I have a separate bookmark section on my computer just for this bike.