2016 Yamaha: WR450F vs YZ450F vs WR250F

Compared to its predecessor, the 2016 WR450F is a completely different animal. Speedo and bashplate aside, it doesn’t share any parts with the 2015-model WR450F. So to get your head around this new WR450F’s make-up, it makes more sense to compare it with the 2016 YZ450F that it’s based on, and with the 2016 WR250F that underwent the same MX-bike-to-bush adaptation process a year ago.

2016 WR450F vs YZ450F

Yamaha has gone out of its way to reinforce that the 2016 WR450F is heavily based on the world-title winning YZ450F. They refer constantly to its “YZ-F DNA” and that it’s “a YZ-F for the bush”. But how different are the motocross and enduro machines? Aside from the obvious stuff – like the fact the enduro bike gets lights, wiring loom, battery, etcetera – here are the key departures the WR450F bike makes from the MXer:

ENGINE
The WR450F uses the same engine cases, cylinder, piston, conrod, camshafts, cylinder head and wet-sump lubrication system as the YZ450F, but it gets a wider-ratio five-speed transmission. Its additional flywheel weight (created by the larger stator and electric starter’s gears) is offset by a slightly lighter crankshaft. The WR450F also gets a different decomp mechanism for improved starting, plus it’s fitted with a cooling fan, and a different exhaust system, mapping and clutch.

CLUTCH
The WR450F’s clutch uses lighter springs, friction plates made from a harder material for added durability and better feel, a judder spring to create a smoother take-up, and a larger 2.5mm clutch cable for a more direct feel at the lever. Also, to help retain more oil in the clutch and improve the consistency of its actuation, the inner clutch hub does not have the five holes that are found in the YZ450F clutch’s hub.

FRAME
The frame and subframe on the WR450F are identical to what’s used on the YZ450F, but the WR-F gets 6mm engine mounts (the YZ450F’s are 8mm) to allow its frame to flex more, and an additional bracket for the sidestand. It also gets an 18-inch rear wheel in place of the MX bike’s 19, and a 2mm spacer under the upper triple clamp that rocks the chassis forward to weight the front wheel.

ROLLING CHASSIS
The 4.5N/mm fork springs are a few rates softer than the 4.9N/mm coils in the YZ450F, while the 56N/mm shock spring is the same as what’s used on the MX bike. Both fork and shock get updated valving for initial plushness, without compromising bottoming resistance. Even though the fork boots are different (to accommodate the speedo pick-up), the offset of both the triple clamps and axle are identical to the YZ450F’s.

ERGONOMICS
The bodywork, fuel tank, seat, handlebars and controls all appear to come straight off the YZ450F. But when you put the two machines side by side, you’ll notice that the WR-F’s radiator shrouds extend 15- 20mm further forward to funnel more air through the radiators, plus there’s less plastic behind the radiators to help duct hot air away more effectively. That said, YZ-F shrouds will still fit.

2016 WR450F vs WR250F

At a glance, Yamaha’s 250 and 450cc WR-Fs look identical for 2016 – the size of their powerplants aside, that is. After all, just like their MX cousins, they both run exactly the same frame, engine and suspension components. Or do they? For starters, the 450’s 270mm front brake disc is 20mm larger. And closer inspection reveals that the 2016 WR450F comes with a few other small but significant differences:

ENGINE
In place of the WR250F’s six-speed transmission, the WR450F uses a wide-ratio five-speed, 13/50 final gearing, and a larger clutch cable (2.5mm versus the 250’s 2mm) for a more positive feel. As the motor is taller, the 450’s air boot is shorter and doesn’t use the ram-tube design found in the 250’s intake to generate torque (but which robs it of RPM). The larger- diameter header pipe on the WR450F means it sits closer to the starter motor, so a small heat shield is fitted to the 450. Also, only the 450 has an earth strap that, somewhat crudely, connects the frame to the LHS of the cylinder.

FRAME
To ensure rear wheel clearance with the battery and electrics, the WR250F uses a 4mm longer shock shaft (which lifts the back of the seat by 10mm). But this clearance issue was taken into account when the YZ450F/WR450F’s frame was revised for 2016, meaning this ‘bandaid’ shock mod wasn’t required. While the 2016 WR250F retains its 22mm triple clamp offset, the WR450F uses 25mm offset clamps to improve steering response. And the spring rates in both the fork and shock are a rate heavier than the WR250F’s.

More…

To read more about Yamaha’s all-new 2016-model WR450F – and to find out how it stacks up against KTM’s mighty 450EXC (the 450cc enduro market’s benchmark) – pick up a copy of Transmoto‘s 2016 January-February issue (#54) on sale now. You can order a copy online, grab one at your local newsagents, or download a digital copy via the Zinio App – just search Transmoto once you’ve downloaded it on your favourite handheld device.