Tested Dirt Bike Products - Independent Race Shop YZ250 Suspension - Experts on Dirtbikes at Dirt Rider Magazine

The new generation of suspension that comes on the 2005 YZ250 is the best we have ever seen from Kayaba. However, the more time I put on the stock suspension of our '05 YZ250, the softer it became, and I thought it could be significantly better with some focused attention. So I ripped the suspension off the blue 250 and sent it to the boys at Independent Race Shop (IRS) in Central California.In stock trim, the suspension is a tad harsh in rough conditions. The last part of the stroke on the fork is too progressive and left me thinking I had bottomed out when I hadn't. I also didn't like how low the fork settled in low-speed, tight corners. It used up too much of the stroke. As for the shock, it wasn't all that bad, other than being a bit soft on flat landings. It was the opposite of the fork, as it was not progressive enough, though this was hardly noticeable.IRS replaced the stock 0.43kg/mm springs with 0.44kg/mm units along with easing up on the valving. IRS went up 2 in the shock's spring rate, from 4.9 to 5.3kg/mm. Once the work was done, the IRS mods were tested at a very rough Glen Helen. I set the rear ride height at 105mm and dropped the fork tubes down to the bottom lines. The IRS modifications worked well; I now had what I desired. The bike sat higher in the stroke when cornering, and the fork wasn't too harsh at the bottom. I was able to use all of the fork travel. The biggest difference was the jarring sensation when I nearly bottomed on the fork was completely gone, and the fork was much more predictable. The 5.3 shock spring was too much; so we replaced it with a 5.1, which worked great for me; now the shock was very compliant and soaked up anything thrown at it.Overall, the bike felt much more balanced; the front end no longer felt low, and I liked how predictable both the shock and the fork were with the new valving and spring rates. The complete customized suspension modification cost $575, and IRS did a great job. If you're a serious racer, you'll find the IRS crew provides trackside support at nearly all the big amateur nationals.
—Corey Neuer