Round front hole on airbox?

[baz666]

Hey all,
I'm working on reviving my 2001 ninjette and the previous owner used a K&N lifelong air filter, which is pretty great. But I noticed a hole on the front of the airbox, just above the back of the carbs. It's round, about 1/2" in diameter. Should there be some kind of vacuum hose going into it? It seems to have the kind of shape that would indicate a hose is missing and the bike is sucking far too much air, judging from the plugs.

Also, the airbox is old and plastic gets warped with time and the two sides don't lock together well so I used silicone to fill and seal the gaps. That helped a bit but the bike is still sucking way too much air.

Thanks in advance for any help.
Baz

[greenaero]

Looking at a parts schematic there is a crankcase breather elbow opening on the front lower left side of the airbox. But it sounds like you are talking a hole in the airbox above the carb boots. If that is the case, it shouldn't be there and would let unfiltered air enter the engine. There should only 2 hose connections in the stock airbox, the I mentioned above at the left front lower corner and another smaller one on the right side front lower corner.

[baz666]

Hey Green,
Thanks for the info. There seem to be 3 vacuum hoses. 1 goes to the petcock from the carbs. 2 goes from the back of the tank and exits to the road. 3 goes from the back of the middle of the carbs and also exits down to the road.

Thanks for checking into this for me. I've never owned an ex250 before so they're new to me but seem pretty standard Japanese bike design.
I also saw Kawasaki has a diagram page.
Thanks again for your input.
baz

[greenaero]

Baz, Thank you! I'm glad I could help.

[baz666]

I checked the Kawasaki diagrams and there's no round hole at the top front of the airbox. So I'm guessing this isn't a stock airbox. There's also a round smaller hole at the bottom right of the airbox, just to the left of where the big crankcase hose is located.
It looks like there should be a hose attached to that smaller hole. It's about 1/4" in diameter and the diagram shows a hole with a plug in it's end attaching to that hole. So it seems it's a plug to drain the airbox if gas gets in there. So I'll have to attach a hose and plug there.
No wonder they previous owner couldn't get the bike to run right. The airbox is full of holes and missing sealing gaskets. So I've used clear silicone to seal the main seam between the two sides.
There's supposed to be a rubber gasket sealing the air filter cover to the airbox so I'll use silicone there as well. What a mess! Hopefully, having a properly sealed and hosed air box will help.
As it is, it barely runs off the throttle and is getting way too much air. The plugs show a little bit of white so I won't run the bike again until the airbox is fixed.
I wonder what bike this airbox is from.
From the diagram, it sure isn't an ex250.
I'm trying to load photos but having a hard time with Flickr.

[dcj13]

Is it possible someone drilled a hole in a stock airbox? Some people can't resist modifying stuff. Especially bikes.

[baz666]

hey Dave,
No, this is definitely not a home job. I just managed to post the photos on another post. For some reason my link wouldn't let me post them to an existing thread. Ah, high tech. A constant mystery.
Sorry to post twice on the same thing but take a look at the pics if you have time.
thanks,
Baz

[Jammerkiller]

Hey Baz,

I'm looking at a stock airbox right now. If you are describing a large nipple-looking piece that aims forward, just above the carbs, it looks like the molded holder for the small "L" bracket that attaches to the frame and helps hold the airbox in place. It should NOT be a hole, unless someone MADE it into a hole. From what you were first describing, it sounded like the hole on the left side of the airbox for Cali emissions. (I only say that since you said you have a 3-line tank) Otherwise, the small hole at the bottom of the airbox and on the right side goes to an "S" hose that relieves crankcase pressure (and some oil vapor) back into the airbox.

Try loading pics by clicking "advanced", then click the paper clip next to the b/w smiley face, and upload your image that way. It worked for me.