YZ - WR fork springs swap

Guys, will 07 - 11 WR450F after market fork springs fit 06 - 07 YZ250F forks ? I have access to 06 YZ250F forks which has lighter spring rate and I have .48 Eibach springs in my 08 WR450F. I was hoping they will swap over. I have used the racetech spring calculator which list the YZ and WR with the same part numbers. I also measured my stock springs and are 5mm long with same diameter.

http://racetech.com/...aha/WR450F/2008

http://racetech.com/...aha/YZ250F/2006

Thank you!

I don't think they will. 06-07 YZF forks should be the SSS fork, which is a different fork than the open bath WR fork. The springs are different. The WR didn't get that SSS fork until 2012.

NO

According to K-Tech, the YZ250F 06-07 uses 43.5mm OD / 455mm long springs

The WR450 07 - 11 uses the same diameter spring but 460mm long, so you''l need a 5mm spacer to make up the difference

I use the 455mm YZF springs in my WR450 2008 model, along with a 5mm spacer and it works fine

Without the 5mm spacer the spring isn't long enough and you will have no preload on the spring when fitted resulting is excessive static sag

The spacer needs to sit at the bottom of the spring (on top of the cartridge) and is basically just a big washer - I made mine on the lathe at work

I also drilled holes in it to allow the oil to flow upwards as the spring compress, because with out the holes the spacer blokes the oil flow hole in the ledge on the top of the cartridge (that the spring sits on)

According to K-Tech, the YZ250F 06-07 uses 43.5mm OD / 455mm long springs

The WR450 07 - 11 uses the same diameter spring but 460mm long, so you''l need a 5mm spacer to make up the difference

I use the 455mm YZF springs in my WR450 2008 model, along with a 5mm spacer and it works fine

Without the 5mm spacer the spring isn't long enough and you will have no preload on the spring when fitted resulting is excessive static sag

The spacer needs to sit at the bottom of the spring (on top of the cartridge) and is basically just a big washer - I made mine on the lathe at work

I also drilled holes in it to allow the oil to flow upwards as the spring compress, because with out the holes the spacer blokes the oil flow hole in the ledge on the top of the cartridge (that the spring sits on)

Well if my WR450F springs are 5mm longer, they should fit the YZ forks? With a little more spring tension.

I wouldn't do it. Use the right spring.

According to K-Tech, the YZ250F 06-07 uses 43.5mm OD / 455mm long springs

The WR450 07 - 11 uses the same diameter spring but 460mm long, so you''l need a 5mm spacer to make up the difference

I use the 455mm YZF springs in my WR450 2008 model, along with a 5mm spacer and it works fine

Without the 5mm spacer the spring isn't long enough and you will have no preload on the spring when fitted resulting is excessive static sag

The spacer needs to sit at the bottom of the spring (on top of the cartridge) and is basically just a big washer - I made mine on the lathe at work

I also drilled holes in it to allow the oil to flow upwards as the spring compress, because with out the holes the spacer blokes the oil flow hole in the ledge on the top of the cartridge (that the spring sits on)

Well if my WR450F springs are 5mm longer, they should fit the YZ forks? With a little more spring tension.

Was getting confused - I wrote my reply thinking you were putting the YZF springs in the WR forks

So, now I've got my brain into gear and you are wanting to fit your after market .48's from the Wr, into the YZF forks - right?

You are right, you will have 5mm more preload than when they were fitted to the WR forks

Just check that you have 460mm long springs, as the Race Tech website looks like they sell 455mm springs for the WR instead of the OE 460mm length

Edited by GuyGraham
Guys, will 07 - 11 WR450F after market fork springs fit 06 - 07 YZ250F forks ? I have access to 06 YZ250F forks which has lighter spring rate and I have .48 Eibach springs in my 08 WR450F. I was hoping they will swap over. I have used the racetech spring calculator which list the YZ and WR with the same part numbers. I also measured my stock springs and are 5mm long with same diameter.

- Did you do the swap --- how to they work?

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