Sag. How much ?

[Team_Oatmeal_Pie]

How much unsprung and sprung sag should I have? Thanks in advance.

[Guest Guest]

i have my bike set for 100mm of sag measuring the suspension fully extended (no weight on the wheel) and then sitting on the bike. when you have the spring preload set correctly you should then measure about a 5mm sag of the bike under its own weight. If this is not correct it means the spring rating is not correct for your weight.

[Bill]

Jeremy at MX-Tech recommends 5mm unweighted and 95-100mm of weighted. If you get no sag unweighted after setting the weighted, your spring is to light. If you get to much unweighted sag, then your spring is to heavy.

Bill

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86TT225, 98CR80, 99WR, WR timing, throttle stop trimmed, air box lid removed, White Bros head pipe, silencer and air filter. Odometer and headlight removed. Moose hand and mud guards. YZ stock tank and IMS seat. Renthal Jimmy Button "highs" and Renthal Soft half waffle grips. AMA, SETRA.

[TallBoysWRF]

If you get no sag unweighted after setting the weighted, your spring is to light. If you get to much unweighted sag, then your spring is to heavy

hmmmm... seems backward to me ?. If your spring is too light wont you get too MUCH sag, not too little???

[tcmII]

When Bill talks about the 5mm sag it is the unloaded sag (bike on the ground without a rider) after the loaded sag (bike on ground with rider and gear) has been set.

If the spring is too light you will have to add spring pre-load and the result is no unloaded sag.

If the spring is too light you will have to remove spring pre-load and the result to too much un-loaded sag.

Also keep in mind that the Yamaha Manual for the 1998 WR400 indicates the stock spring are set for a 160 pound rider. That was a lot of quater pounders ago.

Lastly, make sure that you consider the overall suspension balance. If you change the rear spring to get the correct sag, you may need to also replace the front.

A lot of post on this site recommend Race Tech as a guide to spring selection (www.racetech.com)

[TallBoysWRF]

tcmII...

Thanks, it makes sense now that you explain it. ?

[DeltaT]

If the spring is too light you will have to add spring pre-load and the result is no unloaded sag.

If the spring is too light you will have to remove spring pre-load and the result to too much un-loaded sag.

I am confused...

[TallBoysWRF]

The second "too light" should be "too stiff".