Mixing fork spring rates in an RMZ 450

mark_swart
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mark_swart
Edited Date/Time 6/23/2012 8:17am
Suspension gurus: I think I know the answer to this question, but just wanted a sanity check.

2009 RMZ 450, +30B rider, forks were too soft so I went with MXAs suggested setup of .49 springs and 360cc oil. I've run compression from 11 to all the way out and they are still beating me in the chop and I've had a couple times where the front end pushed going into curves because they are so stiff. Plus with the low oil, they are still using all of their travel over the jumps.

If I put ONE of the stock .47 springs back in, that would bring the average of the springs to .48 and hopefully be less harsh. At that point I would use the oil volume to control bottoming and compression adjustment as needed.
Would the mismatch spring rates cause any issues or wear problems?
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lumpy790
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lumpy790 12/21/2011 8:05am
12/21/2011 8:05am
Where is it beating you in the chop? Is the front rebounding fast enough.....packing?
mark_swart
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mark_swart 12/21/2011 8:12am
12/21/2011 8:12am
Thanks for replying
Specifically braking bumps into turns. Big stuff is fine. Rebound is at 10 out.
kippy450
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kippy450 12/21/2011 9:21am
12/21/2011 9:21am
I think it unwise for MXA to tell people the correct spring rates....it has to be based on weight and type of riding....I am 6'6 and if I did trail riding, my stock spring rate would be perfect...but since I do moto they are WAY to soft. Go to racetech.com and find their spring/shock calculator...that would give you a great starting point.....Stock maybe to stiff for your size. Just my thoughts.
mark_swart
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mark_swart 12/21/2011 11:01am
12/21/2011 11:01am
That's a great point about the one-size-fits all answer.... even for different terrains, not just rider weight. Racetech says .47 (stock). The bike had .44s in it when I got it (woods riding I guess?) so I've never ridden it with the .47? I can get a set of .47s basically for free.
But back to my original question: any issues with putting a .47 in one tube and a .49 in the other? That would give me the stock rate that is on the 2012.

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scooter5002
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scooter5002 12/21/2011 11:50am
12/21/2011 11:50am
No issue at all, and you will accomplish exactly what you want. I have a .52 in one leg and .50 in the other on my bike. Because I wasn't buying .51s. Just remember which fork you put which spring in. I always put the heavy one in the rotor side, so it never gets mixed up. In case you want to go back to straight rate both sides or pull them out when you sell the bike.
mxtech1
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mxtech1 12/21/2011 12:53pm
12/21/2011 12:53pm
You're front break is causing the front end to dive (causing it to compress to about mid-stroke) and then the wheel hits chop and compresses the forks even further and it packs up. How much do you weigh? If you used the race tech spring calculator based on your weight, I would be 100x more inclined to believe their spring rate over any dirt bike mag test rider's "favorite" setting.

Run the .47 springs like race tech recommends, return the oil amount to stock level, compression 12 clicks out, and rebound 10 clicks out. This is a really good standard setting for CRF's. If you can't dial in the forks with oil height and clicker adjustments on the correct spring rates, you're going to need a revalve to suit your riding stlye.

The pushing you are experiencing entering the corner is due to the forks being too low in the triple clamps or not enough sag.
kippy450
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kippy450 12/21/2011 2:17pm
12/21/2011 2:17pm
I know me and I would totally forget which spring is in which fork! I agree more with mxtech1...if you never ridden with stock and can get it for free then I would try that first to get it back to baseline. I have had lots of suspensions from different companies...but I aways struggled with pushing in the corners...which was all of my poor setup...not enough rebound dampening in the forks...more dampening the more it will corner...helped me a ton. So like Mxtech1 said...could be a setup just as much as the springs. Just my opinion...if you do the different spring rates, please post a review, I would like that.
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mxb2 12/21/2011 3:37pm
12/21/2011 3:37pm
kippy450 wrote:
I think it unwise for MXA to tell people the correct spring rates....it has to be based on weight and type of riding....I am 6'6 and...
I think it unwise for MXA to tell people the correct spring rates....it has to be based on weight and type of riding....I am 6'6 and if I did trail riding, my stock spring rate would be perfect...but since I do moto they are WAY to soft. Go to racetech.com and find their spring/shock calculator...that would give you a great starting point.....Stock maybe to stiff for your size. Just my thoughts.
correct springs will do wonders, check race tech s chart and use accordingly.
mark_swart
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mark_swart 12/21/2011 4:45pm
12/21/2011 4:45pm
Guys I really appreciate all of the insight!
Guess I should have added -- I'm 170 lb without gear. My rebound is at 11 out (fork says 1-10 is the range). Sag a tad shy of 100mm, forks down 5mm below the line on them . As for speed, I jump most big jumps at most tracks I ride on. If anyone is familiar with Budds Creek, I normally jump everything but the Big Gulp. The tracks near me now are sandy (not Southwick sand, but still more sand than anything else). The thing felt amazing (on the ground) with the .44 springs when I got it, but of course I was bottoming over most jumps and even one G-out where I didn't even leave the ground.
I want to make sure I'm describing this right -- pushing -- front wheel turns, forks don't compress enough for the front tire to bite, front end washes out. That is right, right? And it is just jackhammering up and down through the braking bump chop. It obviously turned a lot better with the softer springs and that is gone now.
So maybe just more rebound in the fork would have helped? Either way I think I'm way stiff on the forks.
My plan based on your input is to pick up the .47 springs and go with the .48 combo, stock oil height, and try to work with the rebound and oil height from there. I want to err on the side of stiff because the track that I've been testing on doesn't really have any huge jumps and I want to be able to soak up the big stuff when I go to other tracks. The .47 springs will give me the option of .47, .48 and .49 if I don't like the .48.
I will follow up once I get it together and get a ride on it. But of course it's winter on the East coast (and Anaheim is coming up so I'll be glued to the TV and way hungover that weekend ) so I probably won't get a ride until mid Jan, weather permitting!
OneDirtyMXRider 12/21/2011 6:28pm
12/21/2011 6:28pm
mark_swart wrote:
Guys I really appreciate all of the insight! Guess I should have added -- I'm 170 lb without gear. My rebound is at 11 out (fork...
Guys I really appreciate all of the insight!
Guess I should have added -- I'm 170 lb without gear. My rebound is at 11 out (fork says 1-10 is the range). Sag a tad shy of 100mm, forks down 5mm below the line on them . As for speed, I jump most big jumps at most tracks I ride on. If anyone is familiar with Budds Creek, I normally jump everything but the Big Gulp. The tracks near me now are sandy (not Southwick sand, but still more sand than anything else). The thing felt amazing (on the ground) with the .44 springs when I got it, but of course I was bottoming over most jumps and even one G-out where I didn't even leave the ground.
I want to make sure I'm describing this right -- pushing -- front wheel turns, forks don't compress enough for the front tire to bite, front end washes out. That is right, right? And it is just jackhammering up and down through the braking bump chop. It obviously turned a lot better with the softer springs and that is gone now.
So maybe just more rebound in the fork would have helped? Either way I think I'm way stiff on the forks.
My plan based on your input is to pick up the .47 springs and go with the .48 combo, stock oil height, and try to work with the rebound and oil height from there. I want to err on the side of stiff because the track that I've been testing on doesn't really have any huge jumps and I want to be able to soak up the big stuff when I go to other tracks. The .47 springs will give me the option of .47, .48 and .49 if I don't like the .48.
I will follow up once I get it together and get a ride on it. But of course it's winter on the East coast (and Anaheim is coming up so I'll be glued to the TV and way hungover that weekend ) so I probably won't get a ride until mid Jan, weather permitting!
Big Gulp is nuts man, i was racing there. A guy on a 250 hit it. Was Impressed.
mark_swart
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mark_swart 12/21/2011 6:31pm
12/21/2011 6:31pm
OneDirtyMXRider wrote:
Big Gulp is nuts man, i was racing there. A guy on a 250 hit it. Was Impressed.
Yeah, 4th gear tapped, no thanks!!!
kippy450
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kippy450 12/21/2011 10:34pm
12/21/2011 10:34pm
That add info does help. Your plan sounds good...the jack hammer in the bumps is definitely needing more rebound dampening....they are to fast right now....the more dampening should help your cornering...to me a bike pushes when it "pushes" you out of the corner...you can get it to stay on the inside of a rut or corner. When you say rebound is at 11 do you me 11 clicks in or out? Everytime I do a setup, I end up within four clicks either way of my compression clicks. Your weight is spot on for stock, they should work great...its obvious the .49s are to much...considering I am running .50 and I am 6'6 and in the mid-200's!
mxtech1
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mxtech1 12/22/2011 5:18am
12/22/2011 5:18am
Keep in mind your suspension SHOULD bottom out 2-3 times per lap over the biggest obstacles. Most riders will want a soft suspension setup to aid in turning and bite. You want to tune it so you are utilizing the entire fork stroke on the whole track. Don't set the bike up stiff to purposely avoid bottoming because you will then be too stiff on other parts of the track.

To increase bottoming resistance over the big jumps, this is where you need to increase or decrease oil volume. Oil volume controls the last 1/2 of the fork travel. If you buy a suspension oil syringe it would be very easy for you to add or take away oil through the fork bleeder hole. That would allow you to easily tune and adjust when you switch tracks.

Also on the rebounding, you want to run it as slow as possible without packing up. The slower you can run the rebound, the better the front wheel is going to follow the contour of the ground for traction instead of chopping on every bump.

It almost is sounding like you are too soft in the shock, causing the bike to stinkbug and decrease the amount of weight the chassis is putting on the ground at the front wheel.
onenastynotch
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onenastynotch 12/24/2011 11:56am
12/24/2011 11:56am
i have the 2008 model which is the same bike as yours im a 36 year old b rider too ..im 165 lbs i tried mxa recommendations....way too stiff... i played with oil heights from 340 to 380 on the stock valving just couldent make it work...my complaints were the same as yours great in the turns but super harsh in the braking bumps and high speed chop ...i ended up re springin for my weight and having factory connection do the forks and the shock....big difference but still not perfect ill be sending the forks back to soften the valving on the initial part of the stroke to make it plusher....overall tho nite and day differnce......i rode a few bikes that had suspension dont by motorvations racing in nc ...some of the best suspension ive ever ridden....
mark_swart
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mark_swart 12/24/2011 5:53pm
12/24/2011 5:53pm
onenastynotch wrote:
i have the 2008 model which is the same bike as yours im a 36 year old b rider too ..im 165 lbs i tried mxa...
i have the 2008 model which is the same bike as yours im a 36 year old b rider too ..im 165 lbs i tried mxa recommendations....way too stiff... i played with oil heights from 340 to 380 on the stock valving just couldent make it work...my complaints were the same as yours great in the turns but super harsh in the braking bumps and high speed chop ...i ended up re springin for my weight and having factory connection do the forks and the shock....big difference but still not perfect ill be sending the forks back to soften the valving on the initial part of the stroke to make it plusher....overall tho nite and day differnce......i rode a few bikes that had suspension dont by motorvations racing in nc ...some of the best suspension ive ever ridden....
Thanks for the info -- what fork rate did you end up with?
onenastynotch
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onenastynotch 12/24/2011 7:35pm
12/24/2011 7:35pm
onenastynotch wrote:
i have the 2008 model which is the same bike as yours im a 36 year old b rider too ..im 165 lbs i tried mxa...
i have the 2008 model which is the same bike as yours im a 36 year old b rider too ..im 165 lbs i tried mxa recommendations....way too stiff... i played with oil heights from 340 to 380 on the stock valving just couldent make it work...my complaints were the same as yours great in the turns but super harsh in the braking bumps and high speed chop ...i ended up re springin for my weight and having factory connection do the forks and the shock....big difference but still not perfect ill be sending the forks back to soften the valving on the initial part of the stroke to make it plusher....overall tho nite and day differnce......i rode a few bikes that had suspension dont by motorvations racing in nc ...some of the best suspension ive ever ridden....
mark_swart wrote:
Thanks for the info -- what fork rate did you end up with?
i ended up with .45s in the front and a 5.2 in the back as per factory connections reccomendation they also stiffen the valving up in the initial part of the stroke ...i also run 108 mm of sag .......for your weight they would reccomend 5.3 or 5.4 back and prob a .46 in the front let me know how it works out....from me personally taking my forks apart 6-7 times and doin the spring thing .....you wont get the feel your after without a revalve ....after they did my suspension and half a day dialing it in ...it was worth over a second a lap and i could ride about 4 laps longer beore my hands hurt...i have carpal tunnel syndrome in both hands so plush is what i really need and got most of what i wanted..like i said i have to send it back to make a change but worth it overall ......the rear shock revalve made a huge difference in the rough stuff too no longer kicks side to side.....it floats over everything ......let me know how it works out fer ya
mark_swart
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mark_swart 3/19/2012 7:28am
3/19/2012 7:28am
So here's my update: one ride with the .48 rate and it was still too stiff. I then switched to the stock .47 rate and it feels great. Rode at Elizabeth City MX in NC this weekend, it's a fairly rough sand track and quite a few big jumps, so it was a good test overall. Supple but it takes the big hits well enough. Only felt a hard bottom a couple times but those were rider error (flat landing a big tabletop, coming up short on a triple). The right rate allowed me to ride longer and get into a rhythm with less fatigue, and of course it stuck the corners a lot better. I'm happy.
Keep in mind I never had the stock rate before, since it had .44s in it when I got it. But for my speed/weight, stock was the right rate all along.
If anybody needs a set of Race Tech .49s I can make you a deal on them!
ianhendry46
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ianhendry46 3/19/2012 12:29pm
3/19/2012 12:29pm
One more thing, I weight the same as you and im guessing aound the same speed. On y 09, I have found that the sag being set at 104 has worked the best. I have all my suspension done by racetech and thats also what he recommended.

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mark_swart
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mark_swart 3/20/2012 6:05am
3/20/2012 6:05am
ianhendry46 wrote:
One more thing, I weight the same as you and im guessing aound the same speed. On y 09, I have found that the sag being...
One more thing, I weight the same as you and im guessing aound the same speed. On y 09, I have found that the sag being set at 104 has worked the best. I have all my suspension done by racetech and thats also what he recommended.
Thanks -- I might give that a try next time I go out, just for fun. I'm right at 100 now. BTW ianhendry46, is 40 Acres MX still open? I raced there once in 09 it was pretty cool.
rob10238
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rob10238 6/17/2012 4:44pm
6/17/2012 4:44pm
Do you still have the .49 springs? How much shipped to 92345?
Riesenberg448 6/23/2012 8:17am
6/23/2012 8:17am
Rob,

If he doesn't still have the springs, send me an email to chris@racetech.com. I'll get you a great deal on a set of new Race Tech springs to get you taken care of.

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