KTM Motorcycle tests
WHAT IS IT? DR.D’s YZ450F kit moves the 2010–2012 YZ450F engine forward 2.5mm.
WHAT’S IT COST?
www.dubachracing.com or (800) 382-2241.
WHAT STANDS OUT?
Here’s a list of things that stand out with DR.D’s YZ450F engine relocation kit.
(1) The problem.
The MXA wrecking crew does not subscribe to the idea that there is something drastically wrong with the YZ450F chassis. Most of the YZ-F badmouthing is a result of James Stewart’s numerous crashes while at JGR—but Bubba’s crashes are a symptom of his super-stiff setup, not the YZ450F chassis. That said, MXA is on record as saying, “The handling is quirky. On the entrance to turns, when the power is chopped and the brakes are applied, the front-end goes loose for a split second. The front-end wiggles until you initiate the turn and get the front tire to bite.”
In 2010 and 2011, MXA fixed the looseness on the entrance to turns by running a longer shock linkage. This dropped the rear of the bike, which allowed us to slide the forks up in the clamps to make minor changes to the wheelbase, head angle and weight bias, but it wasn’t a cure.
(3) Weight bias.
The YZ450F front-end problem is a byproduct of the new frame that was introduced in 2010. The fork offset was reduced 3mm, the head angle was steepened 0.1 degrees, and the weight bias was relocated 2 percent farther rearward. To get more bite on the front tire at turn-in, many designers, most notably LightSpeed’s Willie Amaradio, moved the engine forward (essentially moving the weight bias back to where it was pre-2010). Yamaha also ran its own test program on engine relocation. All the tests were positive, but the modification was considered beyond the capabilities of garage mechanics.
(4) Relocation kit.
To make the concept available to consumers, LightSpeed and DR.D produced eccentric cams that allowed the YZ450F engine to be moved forward (2mm for LightSpeed and 2.5mm for DR.D). The MXA wrecking crew installed the DR.D kit in one of our test YZ450Fs. The DR.D kit consists of eccentric engine collars, new motor mounts, longer exhaust studs and a 2.5mm-thicker head-pipe spacer.
DR.D provides complete instructions, but be forewarned that some filing of the engine cases and bottom motor mounts is required.
All of MXA’s complaints revolved around the way the YZ450F front-end felt at turn-in, and we can gladly report that moving the engine forward 2.5mm is a big improvement. MXA tested eccentric collars that moved the engine 3mm forward and liked them even better, but they are more complicated to install and have some trade-offs. Dubach chose 2.5mm because it offered the best all-around performance (with some handiwork required), while LightSpeed selected 2mm because it required minimal filing (and still offered increased performance). MXA selected 3mm, but no one plans to make that configuration. It should be noted that virtually every YZ450F rider on the National circuit has a moved-up engine.
WHAT’S THE SQUAWK?
We could complain about having to file the engine cases, but engines don’t move themselves forward without some work, so we accept that this kit isn’t a bolt-on.
If you aren’t complaining about your YZ450F’s handling at turn-in, this is a one-star product. We are complainers.