07 wr450 suspension questions....

14 replies to this topic
  • jrutkows

Posted April 05, 2011 - 12:24 PM


I need to do fork seals on my 07 450, and thought it could be a good time to upgrade some things. This is the only bike I've really owned and I've riden my buddy's KTM 450sx. So I don't have much of a frame of reference but I've read many people complain about the WR suspension and claim it can be made much better.

I don't want to just send everything off somewhere because as my riding develops I want to be able to adjust things myself. I'm also a control freak and want to knwo what mods are done to the bike.

My weight is around 170 maybe a bit light in the summer time, so the stock springs should be right according to racetech. I ride steep rocky trails here in Colorado.

Most of the guys that complain about the stock suspension are 200+ so is the stock valving also set for a 170lbs rider, is that why they need a revalve? If so would I get any more performance from a revalve?

Seems like some people have gone with a "gold valve", some with "smart-performance". Looks like the gold valve is a base vlave mod, smart-performance is a mid valve mod. Would I need or want both? Base valve is really only about compression right?

I've been doing a bit of research and is seems like modern valving works based on pressure differentials at the shim stack, If my understanding is correct can someone explain why everyone tells the heavier riders that the fork is harsh cause it's lower in the stroke? How does that valve know where in the stroke you are? Is this related to oil height/ air at the top of the chamber?

very long post, sorry

please enlighten me, j-

Edited by jrutkows, April 06, 2011 - 07:41 AM.

  • WR450FGreg

Posted April 06, 2011 - 01:09 AM


I'm around the same weight as you j-.

Yes, the stock springs are fine for the average "Joe".

The compression damping in the forks reduces with age and eventually becomes inadequate. This is mainly due to the valve spring losing it's resistence to compression.

I contemplated all sorts of suspension modification companies and products and, being the type of guy who likes to do everything himself, went with Gold-Valves in both ends, which I fitted myself.

I used RaceTech's recommended (for my weight and riding) shim arrangements and I am, in a nutshell, pretty stoked with the result.

Some say the Gold-valves themselves do little, it's the re-shimming that produces the results. The jury's out on that one. i just bit-the-bullet and bought the kits. The work I did got me the results I was after.

I now have a lovely, plush ride early in the stroke and increased resistence to bottoming later.
I found that I don't get nearly as tired as I used to riding the same trails and stuff.

My two cents worth anyway.

Good luck!

  • MANIAC998

Posted April 06, 2011 - 04:01 AM


J, How long have you owned the '07? Are you planning on racing it, or just trailriding? These are some of the things that affect what you need from your suspension. At your weight, if your not racing it, it's probably pretty darn good! At racing speed, or with a heavier rider, the stock forks tend to blow thru there travel rather quickly. This makes the bike move around more than most racers find conducive to fast lap times. And as the hours increase on the suspension, the fluid breaks down and the bushings etc. start to wear some which allows oil to bypass the valving making this more pronounced. Sort of like compression in an engine blowing past worn piston rings.

As for which is better, Race Tech or SPI, I think both are good choices. With each, you get to do the work yourself so you will learn how your suspension works with each mod you chose to do. And you are correct in regards to the front forks valving not knowing where they are in the travel in regards to harshness. My guess is that it's the oil height/air chamber like you mentioned. Hope some of this helps. Maniac

  • gsa102

Posted April 06, 2011 - 05:30 AM


I just had East Coast Suspension do mine, and I am 220#. I got referred to him by some local riders that I trust. He had done the bike before for the PO. I was able to deliver it to his shop and pick it up the same afternoon, and was able to talk to him in person and retain some control that way. He saw that I wasn't using all of the fork travel and went lighter on the fork springs, and heavier on the shock. Much, Much better balance for me. It feels better and gives me more confidence to go faster.

He replaced the forks seals and all suspension oil, and I got all new springs for a little more than I would have spent just to buy the shock spring at the dealer.

Edited by gsa102, April 06, 2011 - 05:33 AM.
add info

  • jrutkows

Posted April 06, 2011 - 07:40 AM


J, How long have you owned the '07? Are you planning on racing it, or just trailriding? These are some of the things that affect what you need from your suspension.

No not racing, had the bike for little over a year now. I was focused last summer on getting the jetting and AP dialed in, I think that is set.

Seems like every month I am riding harder stuff and at a faster pace. I like to push it on the trails I ride. Since I don't race I have no idea about this whole A,B,C rider stuff. I have been the track a few times and the fork does bottom landing jumps, might just be cause I don't know what I'm doing? I'm way more interested trail riding though, so fixing that at the expense of trail riding performance does not interest me.

So I'm still reading everything I can and trying to piece together an understanding of everything. On the base valve, the spring in question that loosens over time, is this part of a blow off valve, when you hit something big it reduces damping? Will that cause it to bottom out?

  • SXP

Posted April 06, 2011 - 11:21 AM


I own an 07 WR450 too, and have the full SPI Phase 4 kit along with stiffer springs. As the stock springs are right for you, and considering the rocky single track riding you plan to do, I think just a switch to SPI's 215/VM2-K5 SPI-3 oil (front and back) would give you considerable gains. That stuff really is a "Revalve in a Bottle". As your skills improve, you might consider the full enchilada, but I think you will be pleasently surprised with just the oil.

  • jrutkows

Posted April 06, 2011 - 11:34 AM


So I've read the valving works on pressure differentials and that the base viscosity of the fluid is not super important since with such a wide operational temperature range, at any given time different weight oils would have the same viscosity anyway. So, what makes his oil different or better? Or for that matter, why choose a heavier or lighter oil? I suspect that the bypass ports would be more affected?

also, if you fast forward to 3:25 you can kind of see what type stuff we are riding. The camera makes it look more mellow, but it's steep, loose and rocky, sometimes roots as well.

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  • MANIAC998

Posted April 07, 2011 - 04:17 AM


Excellent video! And amazing terrain!! And I know alittle about video, so I can tell that that is some difficult terrain to ride!! I haven't tried SPI's fluid, yet, so I can't comment directly on it, but the way I understand it is that his fluid responds uniquely in the speed of the hit that it takes. Do a search on it. There's alot of info on it. Maniac

  • kawi380

Posted April 07, 2011 - 05:13 AM


I have an 08 and weigh around 160lb in street clothes and maybe 180lb all geared up. I kept the stock springs and went with the SPI phase 4 kit and special oil. Off the top of my head I remember the kit replaced the compression spring on the fork to a much larget stiffer spring. I had Dave J set me up with a hybrid moto off road setup, a pure off road setup, and a full moto setup. He actually sent me enough different shims and probably 4 or 5 different setups that I could try. So far I have only been using the hybrid setup as I ride mainly off road desert terrain but I like to be able to air out if needed. The valve stack on the shock was modified slightly to offer resistance to bottoming and stay up higher in the stroke.

I did all the work myself and I think I maybe spent around $250 for everything: fluid, shims, bushings, and seals. An excellent way to go IMAO. I may try changing to the moto version just to see what difference there is.

my $0.02:thumbsup:

  • Leardriver

Posted April 07, 2011 - 07:43 AM


Where do you live? Have you ever changed the fork fluid, or is the factory pudding still in there?
I can help you change the fork seals, and put in some SPI fluid. It would be a huge difference if the factory stuff is still in there.

  • jrutkows

Posted April 07, 2011 - 08:51 AM


I live north-west of Boulder, ~20 miles. I have no idea what oil is in there, have only had the bike for a little over a year. Could very well be original oil. I rode all last summer, and by last fall the seals were starting to leak a very small amount. Two weeks ago I hauled the bike out, and rode 5 MOH. That experience got me thinking more about suspension. I'm sure new oil will make a difference. Since I need to tear it down to do the seals, I'm thinking about changing the valving as well. Still kind of snowy up at 9000ft so I'm just trying to figure out what path to take now. I'm leaning toward a Phase 4 kit now.

  • GuyGraham

Posted April 07, 2011 - 11:30 AM


to the OP

The std fork set up is not good
I've got an 08 450, and hated the forks from the first ride
The compression shim arrangement on the base valve is very strange - instead of the shims being clamped against the valve they are held against it by a big spring
The shims don't bend open as the oil flows through them like most other setups, they are pushed away from the valve without bending
This results in harsh low speed compression damping but they blow through the stroke and bottom out from bigger hits

The springs are under rated
the are quote as 0.46kg/mm but mine measured 0.41kg/mm

Get some springs for your weight, and get the RT gold valve kit
the gold valve instructions have a chart showing incremental steps of shim arrangements so you can stiffen or relax the lo speed or high speed if you are not happy with your set up - this info is invaluable

Now my bike's forks are totally transformed with the gold valves and the recomemended springs and RT's recommended valving
They are compliant over small bumps but resist bottoming really well due to better high speed damping

You won't be disappointed with RT gold valves plus you'll now exactly what has been done if you install them yourself

its the best thing I've done to mine and now I'm really happy with the forks

  • RichGuy

Posted April 13, 2011 - 02:53 PM


Coming from a 08 yz250f with good stock suspension to the 07 wr450 I now ride, the wr really puzzled me. The bike felt really unbalanced to say the least for me at 160 lbs. Yamaha claims the forks are .46s and the shock 5.3. The pink sticker on my rear spring indicates it is actually a 5.5, which I swapped for a race tech 5.2(much better for my weight). My race sag and free sag are right on now with the 5.2 (95mm/30mm). GuyGraham raised a suspicion about my forks now because they still feel very soft even though the stock rate should be correct for my weight. Could the fork springs really be closer to the .41 or .42 range? That would sure answer a lot of questions about the nature of the wr forks if that is the case. I am going to do new seals and the SP phase 4 soon, so where can I get my stock springs tested to verify rates? Any help is appreciated...

  • MANIAC998

Posted April 13, 2011 - 03:22 PM


Yes, GuyGraham could be correct on those spring rates being mislabeled. It seems that the factories have such large tolerances for measuring them that even though they might be listed as .46's they might actually measure out closer too .41's or .42's, or even .48!!! Any suspension shop that might be near you can actually measure them for you. Maniac

  • jrutkows

Posted April 14, 2011 - 10:27 AM


Does anyone have any recommendations of someone in the Denver area that can measure springs? I could always build some setup with a load cell and all-thread, but I have to many other projects.

thanks, joel-


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