Husky’s Unusual-Looking Header Pipe

One of the most striking components of the 2016 FC450 is its unusual-looking header pipe, whose bulbous resonating chamber confuses some into thinking the machine is a two-stroke. Unlike more conventional resonating chambers (that sit separate and parallel to the main header pipe), the FC450’s chamber is part and parcel of the header itself. There are no special chambers or baffles – in other words, the internal shape of the headers mirrors what you see from the outside.

According to Husqvarna’s explanation at the international launch for the 2016 machine, this design is primarily about noise reduction, but there’s no doubt this header delivers performance gains as well. For starters, a header that looks after some of the noise muffling duties means the system’s silencer can be smaller and lighter and mounted 80mm closer to the bike’s centre, which in turn generates chassis agility gains via mass centralisation. Secondly, by changing the way the sound wave returns to the cylinder, this chamber effectively ‘tricks’ the exhaust system into thinking the header pipe is longer than it actually is at lower rpm, and shorter than it actually is at higher rpm – thereby generating power and throttle response gains across the rev range.

For a detailed insight into the new-generation Husqvarna FC450 in which this engine appears, grab yourself a copy of Transmoto’s Jan-Feb issue (#54), which goes on sale on January 4, 2016. This machine is on our project bike fleet for the next six months, after which it’ll get a factory freshen-up up and be won by a lucky Transmoto subscriber in May.