2020 Husky FE350: Power Delivery Mods

Four-stroke engine mods didn’t headline the PR about Husqvarna’s new-generation 2020 enduro range. But that’s not to say the 2020 FE models didn’t come with notable changes to their powerplants. They did. The PR’s ‘undersell’ was simply a reflection of the fact that sweeping changes to the 2020 models’ frame, suspension and bodywork collectively stole the show, and diverted attention away from what were some pretty significant engine mods.

Let’s summarise the powerplant mods that arrived on the 2020 FE350, for example; a machine we’ve had for a few months as a long-term project bike. For 2020, it gets sweeping changes to its cylinder head, aimed primarily at reducing weight and drag. The cylinder head itself is 200g lighter, comes with a new rocker cover, new cooling architecture and, combined with the new cylinder head gasket, an increase in the engine’s compression ratio to 13.5:1 (up from 12.3:1 in the 2019 FE350’s donk). In addition to that, there’s a new camshaft for 2020 (with revised timing and oil supply), an all-new exhaust system (both header and muffler), a new spark plug and plug connector, and new radiators to improve cooling efficiency. And finally, the 2020 FE350 gets completely different mapping to suit the updated engine’s power characteristics, exhaust and airbox design.
And yet, despite all those updates for 2020, the power delivery on the 2020 FE350 feels noticeably less responsive to throttle inputs, mainly off the bottom, but also into the mid-range. If you fitted an aftermarket exhaust (or even a slip-on muffler) before taking your FE350 home from the dealer, you’ll probably be wondering what the hell we’re on about. But for anyone who’s tested a standard 2019 and 2020 FE350 back-to-back, the new model’s smoother and more linear power through the bottom and mid (which is another way of saying less snappy and less responsive power) is hard not to notice.
So, what’s going on? Wouldn’t all those engine mods for 2020 generate more power and responsiveness? Well, the answer to that is twofold, and involves changes made to both the mapping and exhaust on the 2020 FE350. And given the technical nature of those two components, we called on Husqvarna Australia’s Technical Services Manager, Rob Twyerould, to help explain…

MAPPING

As a few savvy Husqvarna dealers and engine tuners in Australia have been able to find noticeably more punch (and less hesitation in the throttle response) in the 2020 FE350 by installing a revised ECU map, we pressed Husqvarna’s Rob Twyerould for his take on the issue.
“Because of different fuel quality and conditions in different countries, it’s inevitable that the production bikes’ mapping is, to some extent, a compromise. The factory simply has to build a safety margin into their mapping to take poor fuel quality into account,” explains Twyerould. “Also, bear in mind that you’re always at the mercy of the development riders when it comes to production bike settings. In addition to their feedback, Husqvarna also pays a lot of attention to the stopwatch. For the 2020 enduro models, it’s true that Husqvarna’s design team opted for a very smooth power delivery. That gave them ultimate traction – and the best lap times – for the conditions they primarily tested the bikes in. But in countries such as Australia – where our fuel, weather and conditions can be quite different from Europe – the production maps do leave room for us to make some good improvements to power and response. This is not something specific to the 2020 FE models; it’s the same case every year. Updating the ECU mapping won’t necessarily give the bike more power, but it will give it more punch and response to throttle inputs at lower revs. And we definitely found that with the 2020 FE350.”
Okay, but specifically what changes are made to the mapping to unlock this broader, punchier style of power? “Via the User Setting Tool, we found we could get more punch and response from the 2020 FE350 engine by ‘fattening’ its mapping at lower RPMs and small throttle openings. That is, making the mixture richer in those areas,” says Twyerould. “This also minimises flame-outs that can happen when you go to pop the front wheel over a log or rock at the last minute, and the sudden throttle movement creates a hesitation, or stalls the engine entirely. The User Setting Tool also allows you to make some other adjustments, such as an enriching setting (called an Acceleration Correction) that basically emulates what the accelerator pump does on a carburettor: adding a squirt of fuel at lower RPMs when you open the throttle really quickly.
“Remember also that Australian riders tend to like as much punch and response as they can get with smaller-capacity models – whether it’s a motocross or enduro bike. That’s rarely the case in Europe, where they tend to ride in wetter and slicker conditions more of the time, and seem to have more of a ‘cultural affinity’ with super-smooth power delivery,” Twyerould went on to explain.

EXHAUST

When you shine a torch down the muffler’s end-cap on the 2020 FE350, it sure looks like it’s more restricted this year. And dismantling the muffler quickly confirms it. Welded inside the central muffler core are two back-to-back steel mesh cones. But how much does this affect the power on the 2020 FE350? And does it have as big an impact on power delivery as the ECU mapping mentioned above? Again, we hit up Rob Twyerould for his take.
“The FE range does have a new muffler design for 2020 and it is a little more restrictive,” says Twyerould. “It’s also interesting that the Husqvarna FE models and their KTM EXC counterparts use different mufflers. The Husky’s muffler core has an additional spark arrestor-type mesh cone fitted. This prevents sparks flying out the back of the bike, and changes the tune of the engine a little. Again, it’s designed to create a smoother power delivery for the 2020 FE models, though I would say this has a smaller impact on the punchiness of the power than the 2020 mapping does. “Some owners are apparently using a long rod to smash out those restrictive cones in the mufflers. Others are fitting a less restrictive muffler off an FC model (which comes with a larger core size and no restrictive cones), or a free-flowing aftermarket muffler from the Husqvarna Accessories catalogue,” Twyerould went on to explain.