Effects of +/- sag and +/- damping - Kawasaki KLR 650 Forum
2008+ KLR650 Wrenching & Mod Questions For repair, maintaining or modifying discussions related to the newly updated 2008 and beyond, Generation 2 KLR650 Motorcycle.

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post #1 of 10 Old 04-13-2017, 06:23 PM Thread Starter
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Effects of +/- sag and +/- damping

After a number of improvements on a new '16, I'm trying to refine my suspension performance. I have front (34 psi)/rear (32 psi) mefo explorers, Eagle Mike fork brace, Cogent complete front fork upgrade (springs, damper cartridges and adjustable caps) and rear Moab shock. I've also adjusted the steering stem according to Patman's process.

Measurements with daily ride setup - me and no other load/equipment
Front Rider Sag - 2 1/8" with caps fully backed out (1.5" mid-way)
Rear Rider Sag - 3 1/2"

I'd like to get close to a balanced reference base where I can then make adjustments and tune to best ride for me.

The current ride feels loose in the front, maybe described as light and overly sensitive, floating or skimming on top of water. For instance, just giving a slight lean as if taking a long weave from right to left in the lane, it doesn't track the direction, the steering slightly hops left with a loose feel. In the rear, taking curves, even conservatively (30* around 35 mph) sometimes feels like it is slipping outwards.

It's mostly the front that will cause a turtle head.

*I have not adjusted damping on the rear shock, set at 14 clicks as shipped by Cogent.*

So the Cogent install guide recommends 70mm - 80mm rear sag (2 3/4" - 3 1/8") but I've also seen other info getting rear sag closer to 2.5".

Is getting front/rear sag to 2.5" a recommended goal? Front slightly less sag?

Next, in layman's terms, what is the general "feel" with increased damping/decreased damping? Due to time of year I'm essentially 100% pavement so my goal is feeling grounded, stable and low heart rate. I live in the CO mountains and even our city roads are twisting, so I'm trying to get the most glued to the road ride.

I appreciate the wisdom anyone can share!

Last edited by Jhawker23; 04-13-2017 at 08:20 PM.
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post #2 of 10 Old 04-13-2017, 09:02 PM
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Jhawker,
As I understand it, one does not want to use more than 1/3 of total travel with ones own body weight.
So 200mm rear travel, minus 68mm = 132mm available travel.

68mm= about 2.75 inches maximum of rear sag with you 'on-board' and feet on the pegs.

So 2.5 inches of sag without your gear or luggage seems reasonable.

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
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post #3 of 10 Old 04-13-2017, 09:11 PM
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I am NOT a suspension guru, but I have been dabbling with this lately and have found a couple knowledgeable guys that have taught me alot.

Sag is more important that anything else, it seems. If you have too much sag you are riding lower in the stroke than you should be. Practically, that means that when you are cruising along nice and easy you are riding with the spring overly compressed. That typically leads to one or two things.

1- The springs are overly compressed and that extra stored energy is causing the bike to rebound harder than it needs to
2- You are closer to the bottom of the the suspension travel than you should be, so compression is also harder than it should be.

I'm sure you are probably familiar with the idea of air gap: the air space inside your forks that lives above your fork oil level. When you are running low in the stroke ( sag too low), you are "wasting" your air gap, which eliminates the progressive cushion effect it should be giving you. It seems counter-intuitive , but having springs that are too soft ( too much sag) will actually make the bike ride firmer than it should. If you need stiffer springs to get your sag right, it will actually make the bike much smoother to ride- especially over quick, sharp hits at low speeds.

Regarding dampening, there's not much you can do with the KLR damper rod forks to adjust this other than thicker/thinner fork oil. If you need more compression dampening ( to get rid of fork dive) you can try thicker fork oil, but then the bike will be harsh over small bumps. You can go with stiffer springs to reduce fork dive and use stock specs on fork oil to prevent making the dampening effect too harsh. But your emulators changes things since you now have a tunable valve in there. But again, running too low in the stroke messes with the settings of that valve. Think of it as running in the high speed area of your stroke, and the suspension is working/valving accordingly...but you are actually still riding at low speed. Things get weird feeling.

General rule of thumb for sag is 1/3. If you have 9" of suspension travel your sag should be 3". General rule of thumb, ofc.

One thing I learned about checking sag is to hold the front brake. Do not touch the rear brake, or have the bike in gear, but hold the front brake. Just try it and see what happens. When you plop down on the bike ( in neutral, all brakes released) the rear will drop and the forks will barely move- if they move at all. Now stand up, hold the front brake and sit back down. You'll see the forks compress far more. That's the best way to check your front sag. Otherwise you can get a false sag reading that is actually higher than it is, which causes your sag to end up being way too low.

Sounds like you've got some good parts to work with. The rest is just patience and tuning. I think you may have too much sag out back. Sounds like you are closer to 1/2 of suspension travel vs the 1/3 that is the rule of thumb. But I don't really remember what the travel numbers are off hand.

Good luck with it all. Tuning suspension is a pile of fun!

Last edited by shinyribs; 04-13-2017 at 09:14 PM.
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post #4 of 10 Old 04-13-2017, 09:12 PM
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I don't know about wisdom, but here goes;

- firstly, congrats on your mods; the Cogent set up and EM fork brace are quality components and I have the same setup on both my Gen1's.

- My bikes are very well planted BUT feel is also a matter of usage and expectations; my bikes are used primarily off-pavement and I run knobbies. While I have a fair bit of road experience (39 bikes and counting, including a ZX6R) I don't push my KLR's THAT hard on the pavement. aggressive, yes but not sportbike speeds. Not sure if what you are experiencing is normal and your expectations are a tad optimistic or if there is a problem. I also don't have any experience with that particular tire.

- As far as sag goes; For my Gen1 Moab and Pro-Series Ultimate, Cogent recommends 75mm - 90mm on the shock with a +/- 10mm......which equals a range of 2.6" - 4" with the median being 3.25". Personally, I've always had good luck with 33% of available travel which, on my 9.1" travel Gen1's, is 3" . It sounds like Cogent does send different instructions for the Gen2 at 70 - 80mm for a mid range setting of approximately 3". Using my normal "rule of thumb" 7.3 x 33% = 2.4", but I'd hate to second guess Rick!


soooooo; if it was my bike, I'd reduce rear sag to 2.75 - 3" and increase front sag to match....keeping in mind that the front has more travel at 7.9". Then I'd raise the oil level in the fork to increase initial firmness by decreasing the air column as the loss of initial plushness isn't as big a deal on pavement only and may help it feel more planted.

Other than that, the only other thing I noticed is that Patman's excellent steering head bearing adjustment procedure still allows for individual variation. I followed the instructions and found that I had slightly overtightened the bearings which led to some handling woes......luckily I had two identical bikes so I picked up on it right away; I loosened the bearing preload an "eyelash hair" and all was well again.

Lastly, and certainly not least; give Rick a call. I guarantee he'll be more than happy to chat with you about your setup and offer you suggestions.......and he knows more about suspension than anyone else I've ever met.

Cheers,
Dave
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post #5 of 10 Old 04-13-2017, 09:14 PM
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Quote:
Originally Posted by shinyribs View Post
One thing I learned about checking sag is to hold the front brake. Do not touch the rear brake, or have the bike in gear, but hold the front brake. Just try it and see what happens. When you plop down on the bike ( in neutral, all brakes released) the rear will drop and the forks will barely move- if they move at all. Now stand up, hold the front brake and sit back down. You'll see the forks compress far more. That's the best way to check your front sag. Otherwise you can get a false sag reading that is actually higher than it is, which causes your sag to end up being way too low.
Excellent reminder. :-)

Dave
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post #6 of 10 Old 04-13-2017, 11:22 PM Thread Starter
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Thanks guys! So getting my front sag up to 2.75" will be trimming the spacer as I have the caps fully backed out, correct? Is trimming the spacer a 1:1 relationship with the increased sag needs (trim 3/4")? Since I'm fully backed out on the caps, it seems to make sense to trim slightly more to get me closer to 6/12 turns, agree?

I have been working with Todd (great guy!) at Cogent. I talked to him about a week ago. The next step was getting sag set correctly and he wants me to call him back to find the best damping settings.

Dave, I understand your perspective that it's really difficult to translate what one person "feels" in relation to expectations. Amen! So I had my wife take a ride with me and asked
If she could feel anything strange and she said the front feels wobbly, and then actually used the same analogy, like skimming on top of water. She also said she was scared on the curves because it didn't feel stable.

In the Cogent install guide, it references using the tool sent with the shock to adjust preload. I may have missed it but I'm 99% sure I didn't have a tool with the shock. Did you have a tool with the shock? If not, what are you using?
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post #7 of 10 Old 04-14-2017, 10:58 AM
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Yep, Todd is awesome too; should have mentioned him as well as Rick. Yes, I'd trim the spacers so that you have your preload adjusters at the mid point at your desired sag that way you can adjust up or down without messing with the spacers again. I'd imagine it'd be 1:1.....but PVC is cheap so you can experiment a bit if necessary.

The shock preload adjuster is a rod with a bend in the end that fits in the holes in the preload nut; it should have come with the shock. I had an Adventure on my 2000 and a Moab with the optional bearing preload collar on my 2001 but I recently upgraded the Adventure with a Moab Pro-Series Ultimate with the remote hydraulic preload adjuster so that one is really easy now! If you didn't get it, call Todd, Rick or Joyce and I'm sure they'll send you one.

Thanks for not taking my comments on feel and expectations the wrong way; it is strange since the bikes feel soooo much more planted with the Cogent upgrades than before. Hopefully you can get it set up to feel the way you want it. Was the Cogent upgrade recent? How did it feel before? ....any other changes other than the steering head bearing adjustment? ......as I mentioned; you may want to play with the bearing adjustment because mine had a very similar feeling when I first adjusted mine and it didn't take much to totally change the feel....

Good luck and keep us posted; I'm very interested in how this plays out.

Cheers,
Dave
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post #8 of 10 Old 04-15-2017, 12:41 AM Thread Starter
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Quote:
Originally Posted by DPelletier View Post
Yep, Todd is awesome too; should have mentioned him as well as Rick. Yes, I'd trim the spacers so that you have your preload adjusters at the mid point at your desired sag that way you can adjust up or down without messing with the spacers again. I'd imagine it'd be 1:1.....but PVC is cheap so you can experiment a bit if necessary.



The shock preload adjuster is a rod with a bend in the end that fits in the holes in the preload nut; it should have come with the shock. I had an Adventure on my 2000 and a Moab with the optional bearing preload collar on my 2001 but I recently upgraded the Adventure with a Moab Pro-Series Ultimate with the remote hydraulic preload adjuster so that one is really easy now! If you didn't get it, call Todd, Rick or Joyce and I'm sure they'll send you one.



Thanks for not taking my comments on feel and expectations the wrong way; it is strange since the bikes feel soooo much more planted with the Cogent upgrades than before. Hopefully you can get it set up to feel the way you want it. Was the Cogent upgrade recent? How did it feel before? ....any other changes other than the steering head bearing adjustment? ......as I mentioned; you may want to play with the bearing adjustment because mine had a very similar feeling when I first adjusted mine and it didn't take much to totally change the feel....



Good luck and keep us posted; I'm very interested in how this plays out.



Cheers,

Dave
So progress has been made! After cutting down the spacers, I have front sag to 2 7/8" (fully backed out) and rear is adjusted to about 2 3/4". This made a big improvement, primarily in two areas, the feel of the road is now present and it feels much more stable/balanced in the curves.

What's interesting is the straight line (moderately slow 20 - 35 mph). It still feels loose and difficult to control. It's as if the front wheel just goes where it wants to.

I've not made any other adjustments than sag for this result.

Dave, to answer your questions, I ordered the cogent upgrade as soon as I bought the KLR new in Feb. The suspension/steering related changes from stock would be the full Cogent suspension, the EM brace and the Mefo explorers.

Where I am today from stock is a major improvement. I just need to get this tuning down. My next adjustment will be slight tightening of the steering head bearings. I also need to take a small amount off the spacer to get my sag at the midpoint of the caps as you said. Then I will take Todd's advice and adjust the shock 3-4 clicks out and start the test rides.




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post #9 of 10 Old 04-15-2017, 11:27 AM
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glad its working a bit better for you; you'll get it dialed. :-) ...on the steering head bearings, I actually had to loosen mine a hair when it was doing what you describe. Perhaps too loose would have similar symptoms but you may need to try it both ways to eliminate the steering head bearings as your issue.

Cheers,
Dave
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post #10 of 10 Old 04-15-2017, 12:01 PM Thread Starter
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Quote:
Originally Posted by DPelletier View Post
glad its working a bit better for you; you'll get it dialed. :-) ...on the steering head bearings, I actually had to loosen mine a hair when it was doing what you describe. Perhaps too loose would have similar symptoms but you may need to try it both ways to eliminate the steering head bearings as your issue.

Cheers,
Dave
Whoa, I wouldn't have guessed it may need to be loosened! Thanks for the tip! I'll actually start with it loose and work my way up.
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