Kawasaki Motorcycle Forums - View Single Post - can lack of OEM airbox effect performance?

idodishez · 06-05-2007

Been working on my 91ZX7. Got it running finally after a melted connector was causing a no spark condition. It appears to be running lean, and falls on its face when given a lot of throttle. Full choke causes it to run better, further supporting the "lean" theory. I took it to the local Kaw shop, and they gave me some suggestions I wanted to confirm.

Some history:The bike is far from OEM. It has an aftermarket pipe. The OEM airbox has been removed, and 4 individual foam type filters were installed in place. This was all done prior to me taking ownership, so I dont know if the cabs have been jetted or not. Now the bike HAS run decent since Ive had it. So its not like the airbox was removed, and it started running like crap. But the guy at the Kaw shop said the missing airbox will cause it to run lean, as it doesnt have the restriction or forced air of the OEM air box. Is this true? I know on a car it makes no difference if you have the air cleaner on or not, unless your midstream a MAF sensor, vacuum, etc. I understand the OEM airbox gets its fresh air from the ducting on the cowling/fuel tank, but is it actually pressurized where it could cause performance issues?

If all this proves to be NOT the issue, where do I find out what jet kits would go with my particular pipe? (Assuming that would be the next step)

06-05-2007	#1 (permalink)
idodishez Newbie Join Date: Jun 2007 Posts: 19	can lack of OEM airbox effect performance? Been working on my 91ZX7. Got it running finally after a melted connector was causing a no spark condition. It appears to be running lean, and falls on its face when given a lot of throttle. Full choke causes it to run better, further supporting the "lean" theory. I took it to the local Kaw shop, and they gave me some suggestions I wanted to confirm. Some history:The bike is far from OEM. It has an aftermarket pipe. The OEM airbox has been removed, and 4 individual foam type filters were installed in place. This was all done prior to me taking ownership, so I dont know if the cabs have been jetted or not. Now the bike HAS run decent since Ive had it. So its not like the airbox was removed, and it started running like crap. But the guy at the Kaw shop said the missing airbox will cause it to run lean, as it doesnt have the restriction or forced air of the OEM air box. Is this true? I know on a car it makes no difference if you have the air cleaner on or not, unless your midstream a MAF sensor, vacuum, etc. I understand the OEM airbox gets its fresh air from the ducting on the cowling/fuel tank, but is it actually pressurized where it could cause performance issues? If all this proves to be NOT the issue, where do I find out what jet kits would go with my particular pipe? (Assuming that would be the next step)