ANOTHER EXHAUSTING RANT...
UK trackdays are under serious threat. Some circuits are now limited to 102dB and even 98dB on some days. Brands GP, one of the best circuits in the country, is 101dB. Sacrilege! Standard bikes that would normally have gone through noise tests a year ago are no longer passing the same test.
The current crop of bikes is the worst in many ways, even with Euro4 compliancy. We seem to be modifying a lot of R1s by fitting longer cans, and the same with ZX-10Rs. The can has to be at least 340mm long to be able to absorb the noise and we’re seeing even the stock stubby cans are failing across the country. After nearly a decade of fashionable shorties, manufacturers seem to be going back to full-length cans, even in racing circles.
We’ve had a surge of enquiries about baffles, although baffles are only good as a restriction of exiting gases and you have to have the right can to absorb the noise at the end of the day (or at the beginning...). Sometimes, a baffle can make a bike louder, like with a jet type effect.
Although some bikes are quieter, it’s the emissions that have been affected more and the majority of newer bikes still have a 98dB reading. I’d love to live next door to a racetrack. You’d get free tickets and listen to engines all day, and maybe even free track time if you really played up. Some circuits test at three quarter revs, and all the valves are wide open and the engine is making all sorts of nasty noises. Most of the noise being picked up by the meter is engine noise and induction bark, not the exhaust itself. Big air tubes and removing scissor gears for race use won’t affect drive-by noise, but they will fail a noise test at a trackday’s static test.
And when a bike isn’t under load it makes more noise, anyway. You have all these mechanical moving items but you’re not putting load onto them to drive something. Holding a constant throttle statically is pretty tricky sometimes, and you’re not feeding the engine the way it’s supposed to be fed, like forced induction. Please, though, no electric bikes…