1. Forks. The forks have issues. They have had spring-rate problems forever, and for 2009 they suffere from the same woes. Our best advice is to go stiffer on the fork springs. We changed the stock 0.47s to 0.49s. Once you have the correct springs, you can raise and lower the oil height to meter the midstroke.
2. Shock spring. Most MXA test riders could live with the stock 5.6 kg/mm shock spring (only the fast or fat went stiffer).
3. Gearing. Virtually every test rider felt that the RM-Z450 was properly geared for its powerband.
4. Exhaust system. In stock trim, the 2009 RM-Z450 doesn’t make a ton of horsepower, and what horsepower it does make happens in the first half of the powerband (it quits gaining power by 8500 rpm and signs of completely at 10,000 rpm). Riders who tried to rev the engine hit the rev limiter very quickly (and the RM-Z450 has a hard rev limiter?unlike the soft limiters used on other brands). We mounted a Vance & Hines XCR exhaust. It broadened the usable power (all the while staying below the rev limiter). It was a very good pipe?and very quiet, too. www.vanceandhines.com
5. Fuel injection. We had excellent luck with Yoshimura’s ignition programming tools (unlike Kawasaki and Honda, Suzuki doesn’t offer a reprogrammer). Yosh’s programmer uses simple plug and play technology and gave us lots of adjustability. www.yoshimura-rd.com
6. Hot-start lever. Suzuki’s hot-start lever is on the throttle side (this is good, because it prevents riders from twisting the throttle during start up), but unfortunately, Suzuki’s plastic lever arm is flimsy and prone to breaking. We opted for a Works Connection lever. www.worksconnection.com
7. Water pump. In long races, our RM-Z450 begins to pop and bang as it heats up. It is very prone to over-heating. Our quick fix was a higher prerssure radiator cap, Maxima Coolanol in the radiator (www.maximausa.com) and a $229.95 Boyesen Supercooler water pump cover and impeller. www.boyesen.com