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Mr_gto
Posted on Thursday, April 10, 2008 - 01:29 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I have a 05xb12r. I have been learning how to tune my suspension. Its pretty dialed in just a couple of questions for any suspension gurus out there. I am doing track days alot and I notice when i go to set up for a corner at high speeds the bike gets a little unstable/wallowing when shifting weight to one side or the other. Anybody have this happen?
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Blake
Posted on Thursday, April 10, 2008 - 04:40 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Try increasing the rebound damping.

What are your current suspension settings?...

Preload: front and rear

Compression damping: front and rear

Rebound damping: front and rear

Do you have the race spring for the rear shock and the race springs for the forks?

What is your full weight including gear?
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Mr_gto
Posted on Thursday, April 10, 2008 - 05:10 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I have it pretty close to the recommended settings for the aggressive ride from the manual. I do not have the race springs. That was an issue I am looking into. My question with that is would i be better off getting some springs set up for me or are the race springs good enough. I am probably close to 250+/- with gear, really depends on my beer consumption vs exercise schedule at the time. I am at work right now so i cant give you my exact settings. I have them written down at home.
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Gentleman_jon
Posted on Thursday, April 10, 2008 - 07:37 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

The "unstable and wallowing" thing is bad.

Real Bad.

At 250 lb.s with gear,(as I am) and with a desire to do numerous track days, you are clearly a candidate for some suspension upgrades.

Heavier, Competition springs front and rear are a must as you already know.

Heavier springs and rider weight usually mean that revising the valving in the forks and shocks will be a very good idea too.

Probably the best results come from working with a suspension expert who attends the same track days that you do, like Dave Moss does at Willow.

That way you will be working with someone who can help you set up your modified suspension with direct feedback from you on the track.

Just ask the racers at your next track day who they use, look around to see who is there, and go from there.

A larger rider on a short wheelbase Buell does not help the stability situation , and I always recommend a steering damper for track use, and it's not a bad idea for the street either.

Needless to say, the best tires, in good condition are an absolute prerequisite as well.

At our weight, the stock suspenders just are not up to the job at the track.
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Blake
Posted on Thursday, April 10, 2008 - 05:25 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I should have said "Preload and Sag". Preload is just the shock/fork adjustment point reading. The sag is the true measure of suspension setup.

Also, what tire pressures do you run (front and rear), and have you measured them both cold and hot (immediately upon pulling into pit after an aggressive track interval)?

I appreciate the "pretty close to the recommended settings", but please post what exactly they are. If you don't have them written down, please do so. Trying to tune a suspension without accurately documenting what you have, what you do and what the results are is a losing battle.

The possible approaches to solving your "little unstable/wallowing" issue are numerous. Jon covered some more of them.

Others include fine tuning fork oil level and adjusting tire pressures.

Even at 250 LBs, you should be able to tune your suspension to achieve a good handling and stable behavior on your Buell XB12R.

Next time out, put a tie-wrap on the fork slider to determine how far the forks are compressing as you are hard on the brakes. If they are bottoming or close to it, aside from stiffer springs, you may try increasing fork compression damping, and/or increasing fork oil level.

But I agree, talk to others at the track who have already worked through similar issues with similar suspension components.

One other option is to raise the front end (lower the forks in the triple tree). That is a very common approach used by some of the top Buell racers in the country.

As a first test of that effect you might try increasing front preload to reduce front sag to a minimal level.

Before you do that, you'll want to actually have someone help you measure what your front and rear suspension sag actually is.

I may well be that you have excessive front end sag and some additional preload may be greatly beneficial.

Like I said, without knowing exactly that you have, it's darn tough to give any kind of reliable specific answer.

Sorry for the haphazard rambling.
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Blake
Posted on Thursday, April 10, 2008 - 05:27 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Minimal front sag would be on the order of 3/4" to 1.0". But it would be most valuable to know what the sag currently is before you take to adjusting it.
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Ft_bstrd
Posted on Thursday, April 10, 2008 - 09:20 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I'm going to have to have my suspension reworked. It's fine if you weight 180lbs, but 260 with gear will just not work.

I'm probably going to head down to Atlanta and have one of the shops there do it up.

I have to run the preload so high, that I'm basically riding a spring and a broomstick.
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Mr_gto
Posted on Thursday, April 10, 2008 - 10:55 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I am going through the set up process this monday with my brother and wife to get all the static,unweighted and weighted sag measurements. We are going to Nashville next weekend to do a track day. I have learned some valuable tips to reset some of my settings. I will scribble all of them down and post it when i do it. As far as tire pressure goes i am trying a new set of Pilot 2ct's out. I am alittle unsure about the pressure to use. I usually do the whole when you come off the track take a hot pressure reading and if its some where around 5psi higher than i started with im good, but if its more or less than 5psi i adjust accordingly.

(Message edited by mr_gto on April 11, 2008)
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Blake
Posted on Friday, April 11, 2008 - 05:23 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Mr. GTO,

Cool, I'll be very interested to learn what you figure out. Fun stuff for sure.


Ft_B,

More mass demands more compression damping. The preload just sets the ratio of rebound to compression travel, it really shouldn't affect stiffness of your ride too much, damping is the big factor there. Remeber that your rear OEM shock is designed to support two up riding. I'd be surprised if it is not up to supporting your waifish, 260LB with gear.
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Slaughter
Posted on Friday, April 11, 2008 - 05:50 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Better off getting recommended pressures from a vendor who has run the tires on a track before. The temperature and pressure difference is only a ballpark but you're really better off getting a recommended pressure from somebody who has handled hundreds of the same tires for people on the track (that's a problem with tires from discount houses)


Static sag in front should be more on the order of 30-35mm (closer to 35). Rear should be set to more like 25mm. A buddy of mine was a bit larger and we ended up trying to get static sag set to those numbers and even with the adjustments BOTTOMED, we couldn't get the sag set... meaning he needed stiffer springs.

In the last few decades, suspensions have improved to the point that static sag settings look "soft" to the old school riders - who don't realize that what they lack in preload, they get back in better control through better damping.

I think there's a chart of recommended spring rates based on rider+gear weights... I'll go see if I can find it.

I'm about 175 pounds, use a .95 spring.

(Message edited by slaughter on April 11, 2008)
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Slaughter
Posted on Friday, April 11, 2008 - 05:58 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)


Spring Rates
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Ft_bstrd
Posted on Friday, April 11, 2008 - 06:14 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Damn. What happens when your combined "dimensions" go beyond the right edge of the chart? : |
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Slaughter
Posted on Friday, April 11, 2008 - 07:31 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I'd give them a call.

Don't know who of our vendors is setup to offer the usual selection of springs - Traxxion Dynamics and Race Tech are two who come to mind.
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M1combat
Posted on Friday, April 11, 2008 - 11:41 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Is it only feeling unstable/wallowing while on the brakes entering a turn while hanging off?

I would try a better grip with the legs and concentrate on being more relaxed with the arms first, but after that... yeah what the other guys said : ).

Or...

If you're talking about when you are transitioning YOUR weight from one side to the other...

I would also recommend trying to do this as smoothly as possible first, then make adjustments.



All that said though...

At that weight you probably should look into the springs and set the sag at least.
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Mr_gto
Posted on Monday, April 14, 2008 - 02:17 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Going to get all of the measurements today. Took the wife camping for her bday this weekend.

Slaughter- I am going to talk to a Mich. guy this track day about pressure since i have never ran these tires. There is usually a distributor at the track day.
So if your static sag should be 25-35mm, what would be the total sag? that seems a little excessive considering you havent even added in weighted sag. Just curious not saying your wrong.

M1- It is when i am shifting from seated to off to the side, once i get over the bike is pretty stable. I try to be as smooth as possible. I think that is a key to fast riding to begin with.
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Retrittion
Posted on Monday, April 14, 2008 - 03:59 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

The theory with sag (as I read it) is to take three measurements (no rider off ground, no rider on ground, rider in riding position[feet off ground]) and then measure the changes between those numbers.

With the rider on the bike sag (as compared to the measurement of suspension fully lifted off the ground) should be:
Front 32-38mm
Rear 28-32mm

Add or reduce spring pre-load to bring your sag into this range.

Also, the zip-tie on the front forks during a ride (make sure you ride as normal for you as possible, including route, speed, etc.) will give you visual evidence on your front suspension travel. If it is pushed to the bottom then your forks are bottoming out and they need more pre-load, and some adjustments to damping might be warranted as well.

My experience has indicated that the suspension for the XBs is a bit light, and that if you weigh more than 220lbs w/ gear on you are near the operating ceiling of the OEM springs, especially for track-style racing. This is a sharp contrast to my buddy's SV1000S rear spring, which is so heavy that it comes adjusted too hard for his 350lbs, 6'6" frame by about 10-15% (Trust me, I was confused as hell when those sag measurements came out, went back and re-did them again. Was funny to tell my friend he was too light for the spring though -- bet he has never been told that before! : ) )

Anyways, if you weigh yourself in gear and then adjust your XB using the chart in the manual you will be in the ballpark from the measurements I took, but after that...it is a bunch of little things that come into play (riding position, grip rigidity, low-shoulders/high-shoulders, knee grip, braking method, wheel balancing, tire type, tire wear, and wheel PSI, wheel PSI, wheel PSI).

The thing that I always remember is a racing tech once told me that the rider can rarely tell what is actually wrong when riding the bike past a certain set of adjustments -- he said after sag, wheel balance, and PSI the modern racer has to rely heavily on the suspension gurus to get setup right. My experience has shown his statement to be pretty much right.

My 2 cents, hope it helps.

Ps. I have a five-part article on motorcycle setup on PDF (size=400kb)if anyone wants it, just message me with an email address and I'll send them your way.
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Slaughter
Posted on Monday, April 14, 2008 - 08:22 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Sag is measured from a fixed point to the axle when the bike is LIFTED OFF THE GROUND. This is Zero.

Now sit on the bike with ALL YOUR GEAR ON. Helmet, boots, leathers. Wiggle a little bit to overcome stiction. Take a few measurements - the average measurement from zero to where you are sitting should be 35mm (front) about 25mm (rear)

These are only starting measurements but will get you in the ballpark. I just call this sag... some call it static sag. Dynamic sag is really not practical to measure.

You would do well to ask a suspension guy working at the track the day you are riding and offer to slip him a few bucks if he'd spot your tire wear after your first couple sessions. That will tell a lot about suspension and tire pressures. You ultimately need to end up working directly with the tire vendor and suspension guru to get the best settings. Nice if you CAN work with somebody at the track.

(Message edited by slaughter on April 14, 2008)
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Mr_gto
Posted on Tuesday, April 15, 2008 - 11:25 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

The numbers are in.
My sag numbers are 36mm rear on the 6th ramp, 43mm front with 4 lines showing
rebound is 1.5 turns front, .75 rear
compression is 1 turn front, .5 turn rear

I did notice that the rear rebounds a little slower than it should so i will be changing that. The front fork rebounds pretty nice maybe needs to be a little more stiff, i did the bounce test to determine this per Dave Moss
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Blake
Posted on Tuesday, April 15, 2008 - 02:59 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

You are much too saggy. joker

I'd recommend that you adjust sag per Steve's recommendations. If the unstable/wallowing issue remains, then try reducing front sag to 30mm. Note effect.

After setting a baseline per Steve's 35mm front sag, 25mm rear sag, please remember to only change one thing at a time.

If reducing front sag helps alleviate the unstable/wallowing issue and the bike also feels good elsewise, try 25mm of front sag. After you change the front sag remember to remeasure the rear sag as well; it will change slightly as you adjust the front. You don't necesarilly need to keep it exactly 35mm, but you need to know what it is for every iteration. Document, keep notes, write it all down including resulting riding impressions.

Suspension tuning is a lot of work, but it will pay significant dividends, and you'll soon be quite adept in adjusting your suspension. : )
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Mr_gto
Posted on Tuesday, April 15, 2008 - 03:40 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Yeah, i agree its a little to saggy all the way around. Your right though, this is fun as hell!!! I am about out of room on the rear spring, looks like im going to have to upgrade! Is there anyone who rebuilds the stock shock and fork? I am sort of on a budget. I would love to have a penski on the back but not gonna happen anytime soon.

Well, ive got some work ahead of me to get the everything dialed in before this weekend. I will post more when i can see the results of my "tuning" Stay tuned, hahahah, just had to say it!!!
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Azxb9r
Posted on Tuesday, April 15, 2008 - 04:09 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

please remember to only change one thing at a time.


Very important bit of advice there, it can help save a lot of frustration.
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Mr_gto
Posted on Tuesday, April 15, 2008 - 04:24 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

When i get my sag right, I will not touch preload again until i get new springs. So I will probably focus on rebound at the track this weekend.
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Rsh
Posted on Tuesday, April 15, 2008 - 07:30 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Obviously the best way to set the sag is doing the actual measurements as you have done then adjust the preload accordingly. With your weight you will have to max out the rear preload to get closer to an ideal sag amount and will probably have to add a line or 2 of preload to the front as well. That correlates with the Buell recommended preload for your weight and bike. Then as you have said you can use the Dave Moss bounce test for the initial setting for the damping, then fine tune at the track.

http://www.buell.com/om/99475-05Y_en/file-5.asp#hd topic000116
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Slaughter
Posted on Wednesday, April 16, 2008 - 06:44 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

If you are out of adjustments, you do NOT need to upgrade, just get a stiffer spring. True for both ends - shock and forks.

Contact a suspension shop. Most dealers only deal with the Buell "race" springs and as far as I know, don't have a selection of spring rates.

You really ought to call somebody like Traxxion, Racetech (two that come to mind). Both are very familiar with setting up racing suspensions for the Buells.
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Mr_gto
Posted on Thursday, April 17, 2008 - 02:49 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Sorry i didnt make myself clear. I dont want to get rid of the fork/shock, just want to upgrade internals along with new springs.
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Trojan
Posted on Thursday, April 17, 2008 - 05:23 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Suspension adjustment is not a black art, but it is very easy to get it very wrong if you are not confident in what you are doing and don't understand exactly what each adjustment is actually doing to the suspension.

Try reading this very good online article about suspension setup and you will be amazed at what can be achieved even using the stock suspension components.

http://www.gostar-racing.com/information/motorcycl e_suspension_set-up.htm

The biggest tip I would give anyone new to suspension adjustment is:

1. Note the settings and position that you start from! That way if you completely it up you know where to go back to in order to start again. It is a common misconception that suspension should be set 'hard' for track and fast road use. You need it to be able to react to bumps and not bounce off them : )

2.Only make small adjustments at a time.

3. Find a road you know very well and which has a variety of corners, bumps etc if possible. Take a notebook with you and the tools to adjust your suspension, then ride up and down the road making small adjustments between each run and noting the settings and effects each time. Before long you will build up a picture of exactly what is happening when you make adjustments and you should be able to predict what needs to be changed in any given circumstance.

4. Making adjustemts to the front or rear suspension will affect both ends of the bike and how it handles, so be prepared to go back and adjust each end together rather than treat them as two separate entities. For instance, increasing rear compression damping will usually require a simlar adjustment at the front in order to cope with the increased stiffness and weight transfer caused by stiffening the rear shock.

5. Stock suspension on production bikes is designed to cater for a huge variety of rider weights and riding styles, from two up touring with luggage to track day/race use. If you really want to fine tune your suspension then a decent aftermarket setup built to suit your weight /riding style is the only way forward.
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Slaughter
Posted on Thursday, April 17, 2008 - 09:28 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Wot Matt sed! ^

The MOST IMPORTANT TOOL you can have is a notebook!

If you are considering reworking your suspension, there are quite a few ways to go - respringing and revalving. If you get a fork spring tool, it makes the work pretty trivial. Your shop manual shows how to pull the forks apart without the spring shooting into the next zip code
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Gentleman_jon
Posted on Thursday, April 17, 2008 - 09:34 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

+2 Trojan.

Thanks Matt.
Great advice as always.

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Slaughter
Posted on Thursday, April 17, 2008 - 09:34 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Here's something that I just "got" in reading your original post: have somebody follow you during your sessions who knows the track very well. They can see where you're braking and what your body position is saying.

I found that the XB just wasn't "feeling right" for me until I had one of the instructors spot me. He noticed that I was just pointing my butt off the seat but wasn't hardly moving my upper body. Next session, the bike was turning MUCH better by my just changing my technique.

Going through a chicane is a complex thing because you are loading the suspension up in a turn and then UNLOADING it as you flop over into the other turn and then loading it up right again. Preload, compression damping and rebound damping are all critical adjustments in a right/left/right kinda move.
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Mr_gto
Posted on Friday, April 18, 2008 - 01:00 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Trojan, i have almost memorized the gostar article i have it printed out also. I just need to apply what i have been reading all winter. I have also started a notebook.

Slaughter, i will be really concentrating on leading with my shoulder and head through the corners. I see too many people sticking their knee and hip out but keeping their upper body in. I need to get a manual, i kind of like the do it yourself method of work.
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Mr_gto
Posted on Tuesday, April 22, 2008 - 01:18 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Well i am back from the track day. I had a blast!! I even went down and had a blast!! Well all I can say is that I need new springs and some more tuning. No matter what I did i was bottoming out my front forks. That was my down fall in the end, plus I tried to pass a instructor on the inside of a tight corner. I ended up running out of suspension travel up front and lost the front end. Lesson learned, but i got some good feedback from the instructor because he had a first-hand view of my low side. I have to give props to Mr Bumpas from Bumpas Harley in Murfreesboro, who was attending the track day on a new 1125R. I broke my shift linkage and lever in the crash, he got on the phone, called his store and had them take one off a bike for me. I went down to his shop and they had it waiting for me. I had it back together and never really missed a lap.
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