I'm in love. No, make that lust. After a frustrating delay while stock arrived from the USA, Project Kawasaki ZRX1200R is now proudly sporting a pair of K&N air filters purpose-built for the Keihin FCR39 flat-side carburettors. I can now go for a decent ride without fear of sucking rocks, birds and small children through the Keihin FCR's open bell-mouths. It also means I'm likely to in-danger myself if the novelty of snapping open the throttle doesn't subside sometime soon.
The Kawasaki ZRX1200R throttle response with the correctly jetted Keihin FCR39 carburettors is instant, with close to maximum torque on tap from 4,000rpm onwards.
The Kawasaki ZRX1200R power and torque dyno curves are famous for being the most linear in motorcycle history, with a meaty 101.5 to 114.2 Nm delivered over a 4,500rpm range from 4,000 through to 8,000. The power curve is as good as a straight line from 1,500rpm all the way through to 8,000rpm.
I can't resist snapping the throttle open at 4,000rpm and basking in the bark from the four-into-one exhaust and induction rattle from the Keihin FCRs. The sound is simply amazing.
The FCR carburettors utilize two K&N filters, which retail for US$ 105 each, finding a seller who wanted to ship them to Thailand was more difficult then I first expected. Fitting the K&N filters is relatively straight forward, with the four carburettor velocity stacks replaced by a set of Sudco airbox adapters. The latter allow retention of the standard ZRX1200R airbox, or the fitting of the dual K&N pods – which I opted for. Cost of the adapters is US$ 240, and like the Keihin FCR carburettors themselves they're precision machined and fit perfectly.
The dual K&N pods provide more surface area than the standard Kawasaki ZRX air filter, plus they look the business hanging off the back of the Keihin FCRs. If you've got it, might as well show-off! The high-flow K&N filters come with a lifetime guarantee, too...
It's encouraging to see that three different manufacturers – Keihin, Sudco, K&N – can make three separate products that fit together so well. Admittedly, it's a bit fiddly getting a standard Allen key onto the adapters' inner bolts – best to use one with a ball-end for angle tightening.