I'm helping to setting up the suspension on a new 04 Yamaha WR450F. I estimate that the rider weighs approx. 250 lbs dressed ready to ride. The stock rear spring is rated at 5.20 kg/mm and with the rear suspension set at 100mm of race sag, there is no free sag at all. The stock front fork springs are rated at .46kg/mm and I assume are too soft for the weight of this rider as well. What should the proper spring rates, both front and rear, be for this rider? In case my estimate of 250 lbs for this rider is too heavy, can someone tell me what the weight carrying capacity is of a rear spring that is rated at 5.2 kg/mm and what is the weight that can be accommodated as the spring increases to 5.3 kg/mm, 5.4 kg/mm, etc. and the same for a front spring rated at .46 kg/mm as it is increased to .47 kg/mm, .48 kg/mm, etc. Finally, after the correct springs are installed on the motorcycle, would a knowledgeable person (someone who has been there done that) care to offer compression/rebound settings for an aggressive rider, who usually rides in the Southern California desert. I've been told that the forks, shocks, springs, and linkage are basically the same for the WR400, WR426 and WR450 through the 2004 model year. Spring rates, compression and rebound settings for all of these models should be interchangeable.