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Static vs Race Sag on my 08 YZ250 - Finding a balance?

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Hi all,

Recently I've been playing with the sag adjustment on my 08 YZ250.

In order to achieve a race sag of approx 104 - 105 mm I've had to settle for 25mm of static sag. I'd prefer about 100 - 103mm of race sag.

This measurement is taken at FULL weight (full tank of fuel, all riding gear, 3L of water and a spare litre of fuel). Overall I weigh about 95kg with all riding gear.

The bike has a 5.4 kg/mm spring at the back and 0.46 kg/mm springs up front.

Now from these numbers I assume that the 5.4 kg/mm spring may not be suited to my application??

I'm having difficulty smoothing out the small chop in the trails (roots, rocks). I also get kicking over log crossings.

Bear in mind my suspension has been set up for 'enduro' conditions (not mx valving).

I was always under the impression that static sag should be somewhere in the range of 25 - 35 mm. Meanwhile, it seems that most guys are setting their YZ's up for about 100 - 103mm race sag. Obviously I can't achieve this using the 5.4 spring.

I guess I'm asking, which number do I chase first, static or race sag - which of the two do I compromise on?? My tuner basically told me to set the bike to about 35mm static sag, in which case my race sag would be around 116mm mark!!

Alternatively, what spring rate should I consider to restore balance to the equation?

Thanks,

Berg

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I was told the exact thing 'at least 25mm static but around 30 is optimal' so I ended up with a 6.0kg rear spring !! It gave me 104mm rider and 27mm statc! I weigh 102kg without kit.

The ride was great for the faster hare scrambles but horrible in the tech rocks and roots...

I have settled for .48 front and .56 rear and its sweet

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with your numbers you are only one rate out, i dont think it will change the feel of the bike by that much.

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I dont know what it is with YZ's but getting the proper free sag and sag numbers just dont work out like with other bikes.

YZ's seem to never have enough free sag numbers even with the proper spring installed, properly preloaded with good sag numbers.

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on my 08 yz450 done by smartperformance

I have .47 up front and 6.0kg rear

27mm satic and 100 race sag

The rear spring is stiffer than recomended and it seems like it would be out of balance but, it is best suspension I have had out of 4 other relvalves on 3 different bikes.

210lb w/ no gear - 1 st bike I have near touched the clicker no matter what conditions

I am no expert rider though, intermediate over road racer skill level

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on my 08 yz450 done by smartperformance

I have .47 up front and 6.0kg rear

27mm satic and 100 race sag

The rear spring is stiffer than recomended and it seems like it would be out of balance but, it is best suspension I have had out of 4 other relvalves on 3 different bikes.

210lb w/ no gear - 1 st bike I have near touched the clicker no matter what conditions

I am no expert rider though, intermediate over road racer skill level

This is what I'M talking about, the normal spring for your weight would be a 5.6, but you run a 6.0 and only have 27mm free sag. Try that on other bikes and you would have 40-50mm's of free sag.

The 5.6 would prolly have you in the 20-25mm with a sag set at 105mm.

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Just a note, I had one of my 07 yamahas done by Factory Connection and they recommend 108mm race sag. I thought it would be terrible at that sag so I started with less. Ended up riding best at right around 108.

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You need to remember that static sag is just a number that confirms wether or not the spring is the proper rate for your weight. You don't "chase" static sag. It's correct if the race sag/spring pre-load are correct.

I think the newer Yamahas can go with a little more race sag. They turn pretty well without having to get into those 95-100mm ranges. I'd say that if you have 100-105mm of race sag without 12+mm of pre-load on the spring to get there, you're okay with the spring thats there. At that point, you should see static sag in the 25mm (+/-) range and you're good to go.

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Hey thanks for the responses everybody.

I'm pleased to hear that having approx 25mm of static sag isn't far from normal.

Given that I'm not the biggest bloke out there, it seemed surprising that going up 2 spring rates over standard was still not quite enough.

So assuming that my shock spring isn't too far off the mark it looks like I'll have to revisit valving to solve my rear end 'kicking' trait. These bloody log crossings are getting the better of me, irrespective of riding technique.

Of course I'm always open to suggestions.

Thanks,

Berg

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Also for those that use the stock Yamaha Ti shock spring make sure you keep those plastic coil end keepers in good condition as it effects the spring rate. As the plastic crushes or splits the spring gets soft. As an example the rate can change from a 5.2 to a 5.0 when the keepers fall out, split or crush. Crap design really.

The stock Ti spring is progressive and requires more pre load than a steel spring at the same rate and free sag numbers will be less.

Most tuners recommend getting rid of the Ti spring and installing a quality straight rate steel.

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Also for those that use the stock Yamaha Ti shock spring make sure you keep those plastic coil end keepers in good condition as it effects the spring rate. As the plastic crushes or splits the spring gets soft. As an example the rate can change from a 5.2 to a 5.0 when the keepers fall out, split or crush. Crap design really.

The stock Ti spring is progressive and requires more pre load than a steel spring at the same rate and free sag numbers will be less.

Most tuners recommend getting rid of the Ti spring and installing a quality straight rate steel.

Hmmm, thanks for the tip 455.

My tuner recommended ditching the Ti spring too. He also mentioned that migrating FROM a Ti spring to a conventional spring with an equivalent rate required a change in valving... I can't clearly remember why, something to do with the rebound characteristics???

Berg

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Just a note, I had one of my 07 yamahas done by Factory Connection and they recommend 108mm race sag. I thought it would be terrible at that sag so I started with less. Ended up riding best at right around 108.

I have a 2010 YZ450F and right now I have 104mm race sag with a static sag of 36mm.

maybe if I went to 108mm race sag my static would come down some.

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I have a 2010 YZ450F and right now I have 104mm race sag with a static sag of 36mm.

maybe if I went to 108mm race sag my static would come down some.

Captain, not sure what you mean by "come down some". Do you want it to be less than 36mm? If you increase rider sag (i.e. going from 104mm to 108mm), your static sag number will also increase. You'd be taking pre-load off the spring to increase the rider sag number and as you do that the static sag will also increase.

I hope that makes sense.

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