Yamaha switched to the new Air/Oil Separate System fork for '05 with great results, but the unit on the YZ450F didn't thrill our riders as it has on other models. Remember what we said about powerful bikes being hard to suspend? The Yamaha's motor isn't doing the suspension any favors with its hard-hitting delivery. While the new fork is plush, it didn't match the Honda's bottoming resistance or, to a lesser degree, plushness. Bottoming and plushness are also the KTM's weakness. Some riders rated its bottoming as better than the YZ-F's, while others felt it was a little more problematic. We tried setting it a bit stiffer than stock, but KTM recommended not to go less than 11 clicks out on the fork. The orange engineers claimed more-aggressive settings do not help bottoming but do add to the harsh feeling. Despite the ratings, none of these forks would keep us from racing these bikes stock.
Shock
Shock performance is another aspect in which Honda earned a gold star. There was no waffling. Every rider saved his highest marks for the CRF, and it also garnered more perfect 10s. The overall rating is a composite of scores for plushness, action, braking bumps, bottoming and adjustability. In those subcategories only one rider awarded 10s to the YZ-F, but nearly every rider awarded 10s to the CRF. Honda made the 450's rear end as good as its fork, and they are a fine match. The suspension action is reasonably plush, well-controlled and trustworthy with few surprises and offers good bottoming resistance. A tendency to kick on braking bumps that we couldn't adjust out cost the YZ-F. The rear shock felt somewhat dead to some riders-as if we needed to speed up the rebound-and that only made the kick more pronounced. Riders tried going in both directions on rebound but in the end stayed with stock.
Our crew did go stiffer on the KTM shock for low-speed compression, but just a bit. Since the KTM has no linkage, it can provide good bottoming resistance on jump landings but still bottom hard in G-outs. Adding high-speed compression helps; the 450 SX was the only bike on which much was done with high-speed compression. As with the Yamaha, the common thread here is bottoming. Bottoming was an issue, but some riders also found a lack of plushness.
Handling
As you can imagine, the bike with excellent suspension action, balanced front to rear, also earned high praise for handling, including a raft of 10s from Jimmy Lewis and nines from Kris Keefer (Keefer didn't award any 10s). You name it, and the Honda does it well. Riders who found any fault with the CRF mentioned stability as its single weakness.
The Yamaha didn't get hit with major deductions; it simply was rated slightly lower in all areas of handling. Its stability was rated well by a unanimous decision, though. Usually, we see the suspension as being linked to a lower rating here, but we believe ergonomic issues and a hard-hitting engine may have hurt a basically fine-handling chassis.
The KTM also was penalized with minor deductions across the board compared with the CRF; and in most cases it rated right with the YZ-F, with the exception of stability. Headshake was evident enough for every rider to mark the chassis down in stability. Again, it isn't as if any of these bikes have scary handling; it's just the CRF has "the whole package," which makes it tough to match.