I bought an 08 kx250f, getting the whole motor rebuilt right now (top and bottom), and I want to set my suspension up right.  I am getting a new shock spring, and ill prob have to do the front springs too.  So do I need to revalve the bike for my weight if the guy before me was lighter then me, and assuming he had it revalved for himself?

Springs are for weight, valving is for riding style.

JBFL, on 05 March 2012 - 12:19 PM, said:

Sweet ..ordering springs soon!

Springs are weight specific, valving is for the kind of riding you do.  If you ride MX, stock suspension is already valved for MX.  If you plan to ride off road, then you would most likely need to get it revalved for that type of riding.

Edited by KcDavis, 05 March 2012 - 12:21 PM.

Im starting MX, and the previous owner did MX too, so looks like its all good

Springs and damping work together, so your springs depend on your weight, and your valving depends on your riding style, riding ability, and your weight.

KJ790, on 05 March 2012 - 12:23 PM, said:

plus the rebound has to controle the weight of the spring meaning ..... a heavier spring will need more rebound dampning.

Since we're on the topic,  I ride an 07 YZ450F I am 150 lbs and just replaced my fork springs and shock spring.  What should my spring preload be set at?  And how do I determine my preload setting?  Do u measure from the top of threads down to top of spring??  I'm a little lost just started learning all this stuff,  I'm pretty much trying to figure out how tight my rear spring should be....

Vman83, on 06 March 2012 - 09:51 PM, said:

The shock preload should be set so that the bike sags the correct amount under it's own weight as well as the correct amount with you on it. Look in the owner's manual and it will tell you the correct amount of sag for both situation. If you cannot adjust the preload enough to get both of the sags correct then your spring is wrong.