ASK THE MXPERTS: 2006 YZ450F SHOCK SPRING RATE QUERY

The 2006 YZ450F rear spring rate is 5.5 kg/mm, but you can ignore the pink marks.a

Dear MXA,
I’m rebuilding a used 2006 YZ450F that has two pink marks on the shock spring. According to the manual, this means a 5.5-rate, unequalpitch steel spring. I thought the 2006 Yamahas came with equal-pitch titanium springs. It should be noted that the spring does have two plastic clips on each end. What type of spring do I have? Steel, Ti, equal-pitch or unequal-pitch?

We asked Yamaha’s Steve Butler, and he confirmed that the 2006 YZ450F came with a 5.5 kg/mm, straight-rate, equal-pitch, titanium shock spring. Your confusion stems from thinking that the two pink marks have something to do with the spring rate or spring type. They don’t. The pink marks are only used to delineate the free length of the shock spring; they have nothing to do with the spring rate. The plastic clips are tell-tale signs that you have a titanium spring. They are stuck between the last coils to keep the Ti spring from coil binding. The YZ125 had Ti shock springs from 2006 through 2013. The YZ250 had them from 2006 to 2012. The YZ250F had them from 2006 to 2010, and the YZ450F had them from 2006 to 2009.

 

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