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YamRZ350

05 450 Base Valves

7 posts in this topic

I pulled the forks apart on my new to me 05 450. The forks action was really poor and they had a ton of stiction that no amount of playing with the axle alignment could fix. Trying to set the sag was impossible.

I found the oil was contaminated with water and even a little rust on the top of the springs. The inner bushings were junk and the oil looked like peanut butter. Really nasty.

The springs in it were marked 48 (.48 I guess?), but the weird thing is the base valves don't have the spring like I've been reading about. I'm sure they're stock as the stem is still peened over the nut. Any ideas what "standard" style base valve fits into a 05 WR450? Or did the 05's not have the spring loaded blow off valve?

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I pulled the forks apart on my new to me 05 450. The forks action was really poor and they had a ton of stiction that no amount of playing with the axle alignment could fix. Trying to set the sag was impossible.

I found the oil was contaminated with water and even a little rust on the top of the springs. The inner bushings were junk and the oil looked like peanut butter. Really nasty.

The springs in it were marked 48 (.48 I guess?), but the weird thing is the base valves don't have the spring like I've been reading about. I'm sure they're stock as the stem is still peened over the nut. Any ideas what "standard" style base valve fits into a 05 WR450? Or did the 05's not have the spring loaded blow off valve?

They are stock and you are trying to make them better, dont waste any money trying to find a stock replacement. Call DaveJ at Smart Perfromance and order his DIY Phase 4 Kit :smirk:

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So just so I'm clear, the 05 WR450 didn't come from the factory with the spring loaded base valves?

Also do you guys have any recomendations about spring rates front and rear? I'm 185 lbs and am in the midst of plating the bike to be used on the street mainly.

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So just so I'm clear, the 05 WR450 didn't come from the factory with the spring loaded base valves?

Also do you guys have any recomendations about spring rates front and rear? I'm 185 lbs and am in the midst of plating the bike to be used on the street mainly.

Im not sure (on the first question). Here is what the stock base valve pretty much looks like:

83e99545.jpg?t=1305302727

As for springs, when you talk to Dave he can recommend what springs.

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Yeah, thats what I was saying. Mine doesn't have that big spring under the piston.

I wonder if the previous owner replaced the valves with something out of a different model or year bike?

Sourcing aftermarket "kits" is going to be a problem if I have totally different, unknown parts in the forks.

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I just purchased and had installed DaveJ's kit. I didn't do the install myself. Dave recommended a local guy. The previous tuner made a lot of changes to valving. The new tuner was able to talk to Dave and get all the parts that the old tuner had removed but were needed in his stacks. Moral of the story, get the Smartperformance kit and work with Dave on any questions!

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