Topic: CB550 intake question

[tg305]

Just recently finished cleaning my carbs for my 78 CB550K.  The bike wouldn't idle consistantly and from reading this board, I'd figure a good thourough cleaning would solve the idle problem.  Needless to say, the idle is improved but isn't where I want it to be.  My question is.... I've noticed a small amount of gas dripping from the hose that vents the bottom of the airbox.  Any ideas as to why.... and a fix?   thanks  Tim

The floats were checked and are at the correct height  and I have no fuel overflowing from the tubes on each carb.

[Gordon]

Are you saying there's gas in the airbox? 

Run the engine with the airbox removed to see which carbs (if not all) are spraying fuel out of the intake.  If they are, seems like that would have to be a valve problem.

[Tim.]

I don't think your gas is coming out the carbs and through the air filter 

What year / model is your 550?  They have some fancy doo-dad that takes crankcase fumes and routes them back into the air box.  A large tube running from the engine to the airbox.

If you remove the airfilter, you'll find a metal grill at the bottom of the airbox.  Pull that out - it has a foam filter that you should replace as per your Service Manual... assuming you have one 

I don't know why you have that much fluid coming out of there, but that's likely where it's coming from.  Get your Service Manual and Parts Manual to see how everything fits together.

[Gordon]

tintin,

Seen it happen before.  An improperly set cam or problem with an intake valve can very well cause fuel to spray backwards through the carbs.  The only fluid that might come up through the crankcase breather would be oil.  Unless there's gas in the crankcase, but then he'd have a much bigger problem than just a wet air filter.

[tg305]

My bike is a 78  and it does have the hose running from the top of the valve cover to the airbox.  There wasn't too much fluid and it wasn't thick like oil.  I haven't checked the valves yet, so I'll do that tomorrow.  Also, I'll drain the oil to see if any leaked into the crankcase.  I had a fouled plug on my 94 ZX7 and I had about a pint  +  of gas leak into my crankcase.   Good suggestion. 

Tim