I have attached a pic and circled the item in question. I noticed today that I didn't have this 2nd filter on my bike. I have been having huge issues tuning it. It looks to be some sort of filter, but I have no clue its purpose or if it makes a difference if its there or not. Any help?

[IMG]local://upfiles/22352/4402D4CCA387424D8C44BD790354BBC1.jpg[/IMG]

 

it' a breather for the air box.

 

why does the airbox need a breather?

on my CBR i have an item similar to this, the tube connects to the carbs, the filter housing is bolted to the airbox.

 

crank case vent?

Also, keep in mind that illustrations are not always correct. Its possible that is an emissions item that your bike may not even have.

 

Its a air cleaner for the CV carbs. The hose connects directly to the vacuume chambers that connect all 4 carbs. either way this hasn't solved my lean mid-range problem. Bike is completely stock, but have a huge problem with the 7-10K range being extremely lean. If I lower the DJ needle I can make it better, but it causes a overly rich condition below 6K. Does the same thing on stock needles.Carbs are complete clean and I have been through every inch of them. I am down to compression or valve timing as a possible problem. I have no clue if this motor has stock internals or been tampered with.