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First time setting sag, seeking advice

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Ok, so I got a wild hair and tried setting my sag after watching a Rockymountainmc video.  That and I raced a harescramble recently and I knew by my exhaustion and inability to turn the bike on a dime that I had to do something about the way the bike was setup.  I'm the 3rd owner of my KLX450r.  The 1st owner was 6' 4" 245 lbs and I knew he had the forks worked by Precision Concepts, but when I called them they said he didn't have any shock work done by them.  The 2nd owner didn't do anything to the bike, btw.  So here is what I came up with in my measurements.  The sag was 144mm after measuring the difference of being on the stand and me on the bike in race gear.  The tolerance for the rear spring is 121.5mm to 138.5mm, from the center of the top shock bolt to the top of the spring.  It was set at 122mm when I got in there, so I turned the lower nut 8 turns down which made it 136.5mm.  I buttoned it all up last night and remeasured the sag today and it is 121mm.  I was shooting for 100mm per the Rockymountain video.  This leads me to believe that the original owner put a stiffer rear spring on the bike.  Please confirm if I'm on the right track in my thinking.  So if I'm doing something wrong here, please let me know.  Racetech springs are $120.  I guess my questions are, isn't compressing the spring like I have to tightest tolerance going to make the bike ride rough? Is it worth getting a spring and bringing the sag down to 100mm? If I do get a spring would be best to error on the side of soft to keep from compressing the spring to max side of tolerance?  Having said all that, I still am not sure I understand how setting the sag will affect the bike.  I know I can't corner worth a flip in comparison to my old KX250.  Yes, forks are being sent in to be resprung next.  I'm pushing 40, riding in intermediate open class and am 5' 11" 195.

unadjusted shock.jpg

adjusted shock.jpg

Bare bike.jpg

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What is your static sag ? Also you don't need to pull the bike apart that far, lube the threads with a spray lube and use a aluminium drift or even brass as your lock rings are steel. 

 

MM 

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I out the bike on a stand and turn the spring with my hands

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Well, I didn't think I needed to pull the bike that far apart either.  Had I known I was going to, I probably wouldn't have taken on the job.  However, I couldn't get the top nut to turn and when I opened my OEM manual it had me taking it all apart.  I did spray PB blaster on the shock and that seemed to help a lot (first time I've ever noticed PB blaster actually help with something).  I'm hoping that it will turn easier in the future now that I've messed with it, but there is no way it will turn by hand, it's just too tight.  At any rate the static sag is about 39.5mm.  Really sounds like I need a softer spring :(. 

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Something isn't adding up ? If the previous rider was 245 you should have had to back off the preload nuts

And if you have 121/39 if you add more preload on to the spring you will end up with 105/25 which says the spring is a tad soft,i tend to like 103-110mm of sag but never 100mm

I think they have put the std spring back on , that's why it's a tad soft for 195

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Well, I know that according to the race tech website the stock fork springs were exactly what I need for single track riding, unfortunately, those are long gone and the springs in there now are way too stiff for my weight.  I would think if the OEM stock fork springs were right for me, that the rear shock would be equally right for my size, but since I can't adjust it the proper sag, it makes me think it's been changed.  I'm not dead set on 100mm, that's just what I've been told.  I'm riding single track now, but plan on riding Baja in November, so I need to set the sag up for desert/single track, which shouldn't be too far off of each other from what I gather.  The problem is, I can't get there from where I'm at.

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If you are 195 and the springs were right for the 245lb guy you will NEVER get the sag set correctly. Find a used stock OEM spring on Ebay etc and go from there. If the fork springs are still set for the big guy you will then need to go lighter to get proper balance. Used springs are just fine and can be found cheap.

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Thanks, I like that idea.  Are there any markings on the springs themselves to identify what they are?  Would be nice to have a way to verify they are stiffer before pulling the trigger on another one.

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The rear spring based on your sags is too soft

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With that much sag no wonder it wouldn't turn....you're basically riding a dirt chopper. With the rear that low the front will feel very stiff also (cause not enough weight on front). I add or remove one turn of preload depending if going to full sand or hard pack track, that's 6mm of race sag change for my weight/spring. You can tell big difference in turning ability with that small change. Don't need to remove anything to change preload on my crf, large screwdriver/pry bar for lock ring and turn spring by hand with bike on stand.

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Ya, start with used springs. I started testing with new, now I'm $400 in the hole and still don't have the correct spring rate.

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1 hour ago, Red800rider said:

With that much sag no wonder it wouldn't turn....you're basically riding a dirt chopper. With the rear that low the front will feel very stiff also (cause not enough weight on front). I add or remove one turn of preload depending if going to full sand or hard pack track, that's 6mm of race sag change for my weight/spring. You can tell big difference in turning ability with that small change. Don't need to remove anything to change preload on my crf, large screwdriver/pry bar for lock ring and turn spring by hand with bike on stand.

One full turn on a Honda is normally 1.5mm per the OEM manual.

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1 turn of adjusting nut is 1.5mm of spring length. Not to exceed minimum spring length of 249mm. This is for OEM spring, my FC spring has different length specs.  That 1 turn gives me 5-6mm of race sag difference, I'm sure through the leverage of the linkage.

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I ordered a stock 5.4kg spring from an '09 KX450 which is supposed to fit my '08 KLX450.  Too hard to pass up for $35. 

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2 hours ago, Red800rider said:

1 turn of adjusting nut is 1.5mm of spring length. Not to exceed minimum spring length of 249mm. This is for OEM spring, my FC spring has different length specs.  That 1 turn gives me 5-6mm of race sag difference, I'm sure through the leverage of the linkage.

Nope. I have oem, FC and Eibach springs of different ratings for my CR. They are all the exact same free length and when adjusted for correct preload give the exact same length when on the bike. If you get a 6mm reduction is spring lenth when tightening the preload collar ONE turn I would love to see a video of that. Or if your rider sag changes 6mm with the same adjustment I would love to see that also. I am still skeptical.

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Please reread what you quoted from me. I'm not trying to argue, but give some info to OP. How much sag difference do you get with 1 turn? I don't have OEM as bike came with FC 5.6 and I installed new FC 5.8 which were slightly different free length.

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My point is that the brand of spring is irrelevant. My current 5.3 spring on my CR250 is a FC. No I am not meaning to argue either. I really find it difficult to imagine one turn on any Honda Cr-CRF or any other linkage bike making a 5-6mm difference in spring length. Just do not think it happens. Whatever, I'll let it rest.

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