First Impression: 2004 Yamaha YZ450F

Justly Refined

With all of the fuss these days being about the new crop of 250cc four-strokes, we almost forgot about our scheduled test day with the Yamaha guys to take delivery of our 2004 Yamaha YZ450F test bike. A friendly reminder on voice mail from PR guru Terry Beal yesterday, however, jolted our “250F-infatuated” memories, however, and we spent today testing the new blue beast at Perris Raceway.

On paper, not much about the 2004 YZ450F appears to be new. Bigger 48mm Kayaba forks, titanium footpegs and—of course—bold new graphics, are the highlights. On the track, however, we were pleasantly surprised to find that the second-generation YZ450F is a kinder, gentler version of the original.


To be honest, some of us had issues with the 2003 model. Personally, I have been wary of big four-strokes for a couple years now, as three separate cartwheeling incidents in 2001 left me bruised, battered and lacking a good chunk of my memory. For some reason, the combination of the abundant power of a big-bore thumper and my non-precise riding style seem to equal disaster, and I’ve spent as little time aboard the bikes as possible. Garth, meanwhile, suffered more than one big crash on the ’03 YZ450F last year, mostly due to its hard-hitting powerband and the tendency of the Lake Elsinore Motocross Park track to become slick as ice when watered. This morning, as I drove to Perris, I couldn’t help but wonder if Garth was really as sick as he said he was when he phoned me to cancel last night and beg me to take his place.

As I fired the big YZ450F up and took to the Perris Raceway course, I immediately noticed that the bike felt tamer than last year’s. Instead of lagging initially, then hitting like a bat out of hell like last year’s bike, the new YZF had crispy clean throttle response and a smoother transition into the meat of the powerband. When I questioned Yamaha R&D’s Doug Dubach and Steve Butler about the new engine character and the lack of changes listed in the press kit, Butler indicated that the ignition curve had, in fact, been altered slightly. After our novice test rider Kyle Puerner rode the bike and got a feel for it, Butler and Dubach leaned out the clip on the carburetor needle one position and asked us to give it another try. The jetting changes were readily apparent, as the initial throttle response became even snappier. On the track, the bike would pull smoothly right off idle without any “herky jerky” hesitation. The ability of the motor to carburete cleanly under a load inspired us to try riding the bike in a tall gear and using the torque of the engine to negotiate tricky tight and rutted corners, instead of slipping the clutch and keeping the rpms up. Of course, more than enough power was on tap and easily accessed by a quick blip of the throttle, and clearing the numerous seat-bounce doubles at Perris was never a problem at all.


Thanks to the beefier Kayaba 48mm fork, the YZ450F inspires much more confidence with a more solid, predictable feel. The stout forks outperformed the wimpy legs on our ’03 bike in almost all conditions, but most noticeably on slap-down landings and in G-outs. The big YZF has a nimble, agile feel and never felt too big and heavy on the tight Perris course. One thing that this year’s bike seemed to do much better was settle into rutted corners. While we often struggled to get the ’03 tracking through and leaned over, the ’04 bike rails through ruts like a slot car.

As a package, we must admit that we were pleasantly surprised with the new 2004 Yamaha YZ450F. Just because the changes don’t look big on paper, doesn’t mean that the new machine isn’t nicely refined. The ’04 YZF is much improved and is destined to become one of the favorites on the TWMX staff.

To see a video of Yamaha’s Terry Beal explaining some of the new features on the YZ450F,, Donn in action, and his post-ride impressions of the big Yamaha thumper, click the link in the upper right column. (Note: We’re chasing some technical problems on a new server setup…you may only be able to load a portion of the video until it’s resolved.)