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how do you know if you need a different spring rate

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i just bought a 07 yz250f used, all stock only 10 hours on it, i race c class, but how do you know if you need to respring also, what weight is the stock suspension mostly set up for, i weigh 135 with no gear on at all, but the thing is im still growing......,

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You want to be referencing free sag and race sag to verify that your spring rate is correct. Set your race sag, if your free sag is less than it should be your spring is too stiff. Race sag is normally about 105mm-120mm and free sag around 30mm.

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You want to be referencing free sag and race sag to verify that your spring rate is correct. Set your race sag, if your free sag is less than it should be your spring is too stiff. Race sag is normally about 105mm-120mm and free sag around 30mm.

Isn't it just the opposite?

If the free sag is less then optimal (around 30mm as you say) that means you have a relatively soft spring that you have to crank down the pre-load too much to get the race sag correct for your weight therefore it doesn't sag much (if at all) under just the weight of the machine.

Or am I backwards?

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Isn't it just the opposite?

If the free sag is less then optimal (around 30mm as you say) that means you have a relatively soft spring that you have to crank down the pre-load too much to get the race sag correct for your weight therefore it doesn't sag much (if at all) under just the weight of the machine.

Or am I backwards?

It can be confusing to some but yes, you are correct.

doc

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i just bought a 07 yz250f used, all stock only 10 hours on it, i race c class, but how do you know if you need to respring also, what weight is the stock suspension mostly set up for, i weigh 135 with no gear on at all, but the thing is im still growing......,

Depends on how fast your growing. Right now at your weight I would go down 1 size on both ends. Once you gain approx 20-30 lbs then stock would be good....

doc

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Isn't it just the opposite?

If the free sag is less then optimal (around 30mm as you say) that means you have a relatively soft spring that you have to crank down the pre-load too much to get the race sag correct for your weight therefore it doesn't sag much (if at all) under just the weight of the machine.

Or am I backwards?

Yeah you are right. I always mix it up. The sprung weight of the rear of the bike is relatively low compared to rider weight. So a soft spring will have little to no free sag in order to achieve your race sag.

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would i even notice it going one size down, any ways, ill probably set my sag and if i cant not get the sag or free sag numbers to line up right i change springs, thanks

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