Tweak that Suspension!

[Frisco]

Budman asked me, and you, to start posting up more moto stuff....,

My FZ-09 had been behaving strangely in high speed corners. The front end would chatter a bit, very disconcerting. I had had Jason at JPH suspension set up my bike a couple years ago, but others had done little adjustments since.

Honestly, suspension seems like a bit of a dark art to me, but I gave it a think and decided it was probably my fork rebound. Per my reasoning, I needed more rebound damping as the front end was coming up too quickly after hitting small bumps. Two clicks of rebound later...... damn, now it’s really bad! I’d made my problem worse.

So, I was out in the garage scratching my head on this problem when I decided to have a look in my service records and found Jason’s settings from two years ago. My current rebound setting was 7 clicks in from his! I backed off 7 clicks and my bike is so much better! I think all that rebound damping was causing my forks to pack up when hitting small bumps at high speed.

Lessons:
First off, I’m totally chuffed that I was able to identify a suspension problem. Historically, I’ve really appreciated a well set up bike, but have had a hard time identifying particular problems. All it took was being 7 clicks off! Ha, ha...
Secondly, write stuff down! It’s easy for these settings to drift when you add a click or two here and there. I’m so glad I had Jason’s baseline to go back to.
Thirdly, read and think about this stuff and you’ll start being able to identify specific problems and address them. Your riding will be safer and more fun!:thumbup

Ride safe, y’all!

 

[Tally Whacker]

Most of us riders simply ride the bike as it is, and don't fuss with all that adjustment nonsense. I mean, who understands any of that anyway? Just set everything in the middle and it's probably just fine.

At least, that was my experience for a long time, and it worked OK. Then, in 2004, I bought a brand new Speed Triple.

The road home nearly beat me to death! It was beyond abusive. Every join in the concrete freeway was a jackhammer blast straight to my spine.

The next day I spent some time and set the suspension (which was surprisingly adjustable, for OEM) to the manual's suggested settings for my weight. Riding became dramatically better.

Then, after a while, I decided that maybe better than that would be even better, right? So I took my forks in to GP Suspension (they were in Portland then) and they completely redid all the internals, and built me a Penske triple clicker. I installed the shock and forks, then did an open track day at Willow Springs, pulling in every few laps to make adjustments from what Dave at GP had set as baseline.

By mid day, I was aiming for the bumps, patches and ripples in the pavement to try to upset the bike, but it just wasn't having it. That bike was so dialed in that nothing would upset it, and I was going faster than I ever had before on that bike.

The most amazing thing about a perfectly set up suspension of that level of quality? It was both firmer and more plush at the same time. It was a dream ride, honestly.

Since that revelation, I've never looked back. Setting up the suspension properly has been the first thing I've done with every new bike I've owned. Well, except my supermoto. I can't figure that one out at all.

 

[NoTraffic]

Another thing to add about suspension is that the fork oil is often overlooked as a constant service item.

As a fellow FZ owner, I've also heard of other owners having good success in moving the handlebar a bit forward and lowering them down on the forks a bit.

Happy riding!

 

[Maddevill]

When I bought my used ZX14, I rode it home on San Pablo Dam Rd. Holy crap ! It handled TERRIBLE. A few times I thought I was going to ride off the road. Really scary. As soon as I got home I set the suspension up to stock numbers and then adjusted damping just a bit. The difference was night and day. Now it handled really well. Apparently the previous owner just commuted on the freeway.
2 years ago I had Jason at JPH revalve both ends and put new cartridges in the forks. Another quantum leap forward. Then I rode a ZX14 with full Ohlins suspension. Drool...

Mad

 

[Hank Wong]

Yes, fork oil is often overlooked as part of a suspension fix.
I bought a 2019 Kawasaki Z900 In March knowing that there is no front fork compression adjustment. I mistakenly thought that I could just add a Race Tech cartridge emulator and swap out the springs like I did with my other Kawasaki. No joy! Kawasaki, in their infinite wisdom, made the Z900 forks unique and difficult to work on such that nobody, including Race Tech, would make a kit for it. The Race Tech rep says if they make a kit for it, the labor cost to install it would make it not cost viable compared to a set of drop in cartridges. At the high end, a set of Ohlins drop in cartridges would cost $1500. At the low end, a set of Adriani would be $1000. I did the next best thing and change fork oil weight to add compression by trail and error. It is a pain to pull the fork every time instead of turning a dial. But at least I only have to do the left fork. The right fork is inert and just along for the ride. After a few tries, I settled at a 60/40 mix of 10 wt and 15 wt fork oil, about 47 cSt @40C. Now the Z takes the torn up Moody road and Page Mill road in stride and at speed. I didn't have to spend the big bucks on a set of cartridge kit.

 

[dravnx]

I'm a big Dave Moss fan. I always get him to set up my suspensions and then record the settings. I can fine tune them but if I get too far out, I reset to Dave's and try some more.
I pulled the forks out of my FJR1300 with 51,000 miles and brought them to Dave's house ( he lives in Cobb now) and had him replace the fork oil. He put 20 wt in there and set the suspension to what he thought was correct. I was pretty skeptical but after I re-assembled the bike and took it for a ride I was pleasantly surprised. I then installed a Nitron shock. I was able to attend one of his clinics to tweak the suspension even more.

 

[gixxerjeff]

Dark art is right.
The two most viable options before you are
1) Let Dave Moss touch it
2) Sell a kidney and step up to some Ohlins.

 

[ThinkFast]

Suspension - for me it's been one of those things I more or less ignored, until I couldn't. Kinda like good acting - you know it when you don't see it.

When I first started racing I bought a set up SV and did 14 race weekends on it with around 80 starts my first season (CCS-Midwest). It wasn't until the end of the season that I even thought about looking at my suspension setup. It turned out I had a Penske triple clicker on the rear. Never touched anything on it that first season - and won three regional amateur championships.

It was very different story, though, when I moved up to experts the next season. Podiums were a thing of the past, and I found myself scrambling just to keep up with the back of the pack. So I hired a suspension tuner for the day and started learning how to work with him - that in itself is an art. He can't help you if you can't do two things:

1. ride consistent lap times - at least within a couple tenths per lap or better.
2. identify what the bike is or isn't doing in terms that you can then communicate to him.

That was a gamechanger for me - my laptimes immediately improved by a full second, and then over the next few weekends another half a second or more. Cool.

I'll save my street suspension story and lessons learned for another post. The short answer is: start by setting your sag. You can't tune your suspension until you've got the sag dialed. And it's pretty easy to do without fancy tools or Yoda-level knowledge.

 

[N4teTheGreat]

Dave set my bike up shortly after I bought it, 18k miles later I'm getting some odd tire wear, probably time to refresh for the fork and shock oil. Also, I've certainly gained some weight not all of which can be blamed on Covid, so I suspect my sag is too soft, I've found I bottom the fork and end up skipping the front tire under hard breaking, which is not a great sensation mid corner.

 

[PorradaVFR]

Just had my fork oil changed - it’s a maintenance item every ~18-24 months for casual street riders and the different is always notable. While my bike has limited adjustment I had Dave Moss adjust it and you can easily feel it when turning in and when on irregular pavement.

If you don’t remember or have never changed the fork oil (and in my case changed springs that align to your weight) you’re not getting all the bike you paid for. Do it and be aware the first time you brake and it feels like your front end is WAY firmer.

 

[Frisco]

Great stories and insights! :thumbup

ThinkFast - can’t wait to hear your street setup story.

 

[ScottRNelson]

I've had Phil Douglas (Aftershocks Suspension) adjust the suspension on four bikes. I was amazed at how he could bounce a bike up and down a few times and know how to adjust it.

He definitely fixed an issue I had with my Ducati ST2. It tended to work its way to the outside of a bumpy corner. After he adjusted it the bike held the line well in the same corner. I had him do my 888 SPO too, but couldn't really tell any difference. He did my XR650L for a twenty buck donation at one of those Livermore Police events. That helped balance the front and rear. I am still using the same settings many years later.

Unless the suspension is way off, I can't tell what it needs. My KTM 790 Adv R has all kinds of adjustments available, but I'm happy with how it behaves both on twisty roads and off road, so I'm not touching it. :x

 

[dtrides]

Carl...2021 MT 09 SP....nuff said..
DT

 

[Frisco]

Carl...2021 MT 09 SP....nuff said..
DT

Progressive forks, Penske, tons of Woodcraft, .... I already have one!

Seriously though, I’m interested in checking it out. Not sure about the new style, more ccs is nice, but maybe it’s just to compensate for more restrictive emissions.

Duncan, your in my neck of the woods now, let’s get out for a ride!

 

[dtrides]

I would like to get together when ever the time is right.
I too would like to have some seat time on the new 900 SP ( as well as the Aprilia RS 660!)...
The bikes just keep getting better! Lucky us.
DT

 

[ThinkFast]

Street story - replacing my stock ESA shocks on my BMW 1200 GS. They were pretty much done at 40k or so, but I kept riding them for a few more thousand miles just to make sure. I started scaring myself a bit when I was getting bounced off line in corners that the bike normally would've railed, so I decided to pull the trigger and hit up Ted Porter at the Beemershop for some replacements.

Originally was going to go with a low-end ESA plug and play shock, so I gave Ted all my info and he got them together for me. He doesn't do shock swaps anymore at his shop, and I didn't feel like wrestling the front one out, so I took my bike to an indie shop that pulled the shocks for me. Meanwhile and I walked over to a car rental place and picked up a cheapie, then ran my old shocks over to Ted's.

After much discussion with him I decided to go with non-ESA shocks, which he had on hand and he built them for me while I waited. Then back to the indie shop that put them on.

He said I'd have to play around with the sag, but I was aiming for 60mm on the rear. He said I didn't need to worry about the front - I guess these bikes are set up in such a way that the front suspension is more set and forget.

So I get home and start working on the sag for a one up, no cargo ride. Came up with my own innovation for doing it by myself by putting a yardstick under the pillion seat, and using it as the height guage. Then I parked the bike next to the wall in my garage so it was balanced perfectly upright. I had already measured the rear sag without any weight on the rear wheel versus with the bike upright on the ground, so all I had to do was get the sag with me on it. Which I did with my yardstick under the seat and a mark on the wall.

Once I had that nailed, I used the same mark to adjust preload for one up, full camping gear; two up, no gear; and two-up full camping gear.

Keeping notes is key, because then I had to play around with the rebound to get it dialed in a bit better.

Ted said once I had the sag set correctly, if the bike feels too stiff or firm I should just dial out some rebound; and vice versa if it felt too mushy.

I'm still playing around with this a bit, but overall have a pretty good handle on the settings. And it really does make a noticeable difference in how the bike handles and my confidence riding it.

Get the sag right first. Then read up on how suspension works and what compression and rebound do, and experiment with it. Keep good notes and you'll start to figure it out.

 

[kuksul08]

Rebound is actually one of the most dangerous adjustments on the bike. Sure, they include it to account for a wide variety of rider weights and spring rates, but adjusted wrong, it can result in a huge loss of traction.

In general you should run the least amount of rebound possible to have good grip and body control. Too little results in a pretty sloppy feeling ride, but too much can cause a slide.

 

[ThinkFast]

In general you should run the least amount of rebound possible to have good grip and body control. Too little results in a pretty sloppy feeling ride, but too much can cause a slide.

I always go full Goldilocks: not too little, not too much. Juuuust right :teeth

 

[Holeshot]

In general you should run the least amount of rebound possible to have good grip and body control. Too little results in a pretty sloppy feeling ride, but too much can cause a slide.

Rebound controls how fast the suspension regains travel. Spring is what actually does the work to regain travel. Just a small comment on rebound dampening.

Most stock suspension settings work for less than half of the amount of clicks. If a fork leg has 20 clicks of compression, the working zone will be within an 8-10 click range, generally. On low quality stuff, you're lucky with 3-4 clicks of workable range!

 

[Frisco]

Well, it turns out that rebound adjustment helped, but didn’t really solve my problem.

I’m still noticing some high speed (70-80 mph) instability from the front end. It’s kinda bouncy, pretty high frequency and worse when turning. Time to make more adjustments. My forks were raised in the triple clamp 14 mm! Honestly, what was I thinking. I’ve read that raising the forks has the bike turning quicker, but too much can make the bike unstable. I moved them down to a more sensible 8mm above the triple. Hope that helps.

Question: What sort of ‘instability’ due you experience when forks are raised? Am I on the right track?

Thanks!