Airfilter for 92 ZXR
K&N has discontinued the filter for the 91-92 ZX7. Why, because it didn’t flow as good as the stock filter and on my dyno with many attempts, always made at least 2 HP less than the stock filter.
I don’t believe in running a street bike without a filter, but the 92 R model with the OEM flatslides and velocity stacks makes 7 more HP, than with the airbox. I never could get the airbox to work correctly on the 91-92 models without using the intake snorkel completely stock. Every time I tried it without the snorkel, with holes drilled in the box, it made less power. I must have made over 150 dyno runs trying to improve. That airbox needs to be totally stock, though you can remove the internal metal screen. I wound up buying a brand new airbox from Kawaski, and let it go at that.
Again, I cant emphasise how important that snorkel is on that 91-92 box.
Interestingly enough in 1993 I helped a racer dyno his new watercooled 750 GSXR, in that case that bike uses a rubber round intake snorkel. We heated that snorkel and used a device for expanding and repairing exhaust pipes to stretch and enlarge the opening.
Yes that was cheating, but that bike made it through every tech inspection that year.
That was good for 4 HP. I don’t understand why the box works so poorly on the 91-92, I just know each and every mod I tried would not increase power, short of completely removing it.