A 2005 Yamaha XJR1300 was bought in by its owner; he’d fitted cans and noticed it was running a bit rough. In the later years of this model (and this is the carb’d bike) Yamaha fitted emissions equipment like secondary air injection to get it through the testing. To be fair, it created a lash-up, made much worse by the addition of things like free-breathing exhaust cans.
We started by blanking off the secondary air and adjusted the airbox itself as they’re quite restrictive. We then fitted FJR inlet rubbers as they have a bigger diameter than the stock XJR items, then added a K&N filter and corrected the fuelling on the needle and pilot jets.
And Bob’s your uncle! Power rose from just shy of 100bhp to 110bhp, with much nicer throttle response all-round.
Getting this engine through emissions testing didn't help it in the long run...
