TOO Much Wallow in sweepers

[posplayr]

Posplayr,

Got a new Avon Roadrider AM26 in 130/70-18 on the way from www.motorcyclesuperstore.com 85.00 shipped.

I've replaced the bushings on the rear shocks, MUCH better material from Autozone!!

I'm going to replace the Wheel bearings this weekend since i have to pull the wheel to replace the tire, The Carrier bearing has been replaced already.

Thanks for all the input and help, I'll let you guys know how it handles with the new tire, bearings and fresh shock bushings when i get it all back together....AGAIN!!

Tommy

Make sure that you check your sag numbers (front and back) to see if you are close. Do a search if you don't already know how to do this.

Not sure if what I described as my problem is occurring with you but the weight transfer from front to back (when the rear compressed more than front) is what caused the woller (similar to what Steve is describing). In mine I had too stiff of a front due to too much stack height in my springs with Progressives and Cartridge emulators. 20 wt could contribute to the same thing. Front doesn't compress, the rear does and the weight transfer front to rear puts more sidewall pressure on a tall rear tire. You have aggravated the problem also by going two sizes over as well.

I would get a stock GS wheel that normally carried a 120/90-18 tire. The 130/70-18 will fit it nicely. When you change the tire, I would drop the front down by the 0.3" to compensate for the shorter rear tire as well. You loosen the triple clamp and allow the stanshions to slip up by the 0.3".
At least you will have separated the rake change from the side wall change this way.

Also what size rear wheel do you have? You might have improved things somewhat with the shorter side wall, but you still going a tire two size over v.s. just one.

I'm afraid you might have selective reading and are jumping to what seems like an easy solution in a new rear tire. Before you change the rear tire follow this:

1.) If you are putting something back to stock like wheel bearings and bushings fine. Hopefully this gets rid of some variables and will not hurt.

2.) Check your Ft/Back Sag numbers to confirm your spring rates are OK and adjust preload accordingly.

3.) Go back to the 15 wt oil in front.

4.) Road test over the dippy frost heaves as described by Sandy. My problem manifested itself when in a banked heaving conditions only.

http://www.thegsresources.com/_forum/showpost.php?p=1197199&postcount=5

Put tie straps on the front forks to see how much travel you are getting. Heavier oil is not really a replacement for more preload. I'm running 15 wt in all my bikes.

See how the bikes rides and if the problem has gone away or been moderated then......

5.) Change the rear tire prefereably on a wider wheel. In this order you will be able to tell the difference due to the wider tire independent of all the other potential problems. This is non stock and an experiment (also increase tire pressure).

[posplayr]

more tire size discussion; remember every one does not push their bike the same way

http://www.thegsresources.com/_forum/showthread.php?t=150504

Also here is a description of the problem I was having

http://www.thegsresources.com/_forum/showthread.php?t=140521&highlight=sag

Looking at it reminded me that with those avons you can really bone them upon pressure. I would also confim if there is a difference between say going from 30 psi rear to 42 psi rear as suggested by Salty:

Where did you get your tyre pressures? Avon recommends 36F 42 Rear for my bike... A little more pressure should help to stiffen the sidewall.

[Mysuzyq]

Are you riding this GS after owning a modern sportbike? Just wondered (with your handle and sig graphic)...they do feel different, esp. whilst cornering. The older GSs while not unsafe, are nowhere as confidence-inspiring as the modern bikes, and may well feel 'flexy' when pushed in the corners, compared to a Gixxer....an altogether animal, in terms of the tires, chassis, and geometry.
Tony.

[gixerbike1]

Tire and rim size

Make sure that you check your sag numbers (front and back) to see if you are close. Do a search if you don't already know how to do this.

I'm going to do that this afternoon, i have the steps saved as a favorite.

Not sure if what I described as my problem is occurring with you but the weight transfer from front to back (when the rear compressed more than front) is what caused the woller (similar to what Steve is describing). In mine I had too stiff of a front due to too much stack height in my springs with Progressives and Cartridge emulators. 20 wt could contribute to the same thing. Front doesn't compress, the rear does and the weight transfer front to rear puts more sidewall pressure on a tall rear tire. You have aggravated the problem also by going two sizes over as well.

The front isn't too stiff and has good movement, it's actually a little softer that i like.

The wallowing i feel is coming from under my rump and when your heeled over it's as if the bike moves away from the pavement and then back toward the pavement.

It's like the bike is going up and down, but it's doing it sideways, if that makes sense

The front end is stable, and the reason for the 20wt oil was that I had the stock springs and it was WAY TOO soft and had too much sag.

I would get a stock GS wheel that normally carried a 120/90-18 tire. The 130/70-18 will fit it nicely. When you change the tire, I would drop the front down by the 0.3" to compensate for the shorter rear tire as well. You lossen the triple clamp and allow the stansions to slip up by the 0.3".
At least you will have separeted the rake change from the side wall change this way.

Also what size rear wheel do you have? You might have improved things somewhat with the shorter side wall, but you still going a tire two size over v.s. just one.

I checked the tire chart for the tire I just ordered and the manufacturer states that the tire will work fine on rims from 3" to 4" my rim is 3.75" So this shouldn't be a problem.

I've already raised the forks in the trees by 10MM, should i go more ?

I'm afraid you might have selective reading and are jumping to what seems like an easy solution in a new rear tire.

Not really, I just realize that the tire sidewall is awefully tall and the shocks are brand new and were adjusted up to where the ride is firm now and i know the needle bearings in the swing arm are good and have new grease in them.

I checked for excess play in the swingarm before i put things back together and it was good to go.

So, to me the most logical and simple answer was the tire, of course when i got the dunlops i didn't have anyway to check what size rims these would properly work on, the front size is stock.

Before you change the rear tire follow this:

1.) If you are putting something back to stock like wheel bearings and bushings fine. Hopefully this gets rid of some variables and will not hurt.

Cool

2.) Check your Ft/Back Sag numbers to confirm your spring rates are OK and adjust preload accordingly.

I plan on doing this after work, last night was raining a bit too much.

3.) Go back to the 15 wt oil in front.

I can do that.

4.) Road test over the dippy frost heaves as described by Sandy. My problem manifested itself when in a banked heaving conditions the most.

Don't really have any of those here in Va. pot holes mostly

http://www.thegsresources.com/_forum/showpost.php?p=1197199&postcount=5

Put tie straps on the front forks to see how much travel you are getting. Heavier oil is not really a replacement for more preload. I'm running 15 wt in all my bikes.

Is there a chance I might need to cut my springs and install a spacer ?

See how the bikes rides and if the problem has gone away or been moderated.

Thats just what i plan to do, I'll post my result's tonight for the sag measurements front and rear to see what you think.

5.) Then change the rear tire prefereably on a wider wheel.

I'm not sure what wheel will work with this bike since most of the GS's are shaft drive, any idea's on that one ?

In this order you will be able to tell the difference due to the wider tire independent of all the other potential problems.

I will do all of the other stuff you have listed above before going to the different tire, I will see if i can cancel the order before it ships out today.

This is non stock and an experiment.

True that

Thanks for all the input and i'll keep you updated.

Tommy

[Turtleface]

I agree with Jim. You're changing a LOT of variables at once. Before you do anything, check your sag measurements and all that. There should be a thread around the boards for setting up suspension, or you could google for one of the many available. You need to know where you're at, before you can know where to go.

[posplayr]

I'm going to do that this afternoon, i have the steps saved as a favorite.

The front isn't too stiff and has good movement, it's actually a little softer that i like.

The front end is stable, and the reason for the 20wt oil was that I had the stock springs and it was WAY TOO soft and had too much sag.

I Thought you had changed to progresssive springs up front. Do that if you have not.

I checked the tire chart for the tire I just ordered and the manufacturer states that the tire will work fine on rims from 3" to 4" my rim is 3.75" So this shouldn't be a problem.

Wow if your rim is 3.75" then go with that new tire.

I've already raised the forks in the trees by 10MM, should i go more ?

I was thinking the opposite, if you lower the rear axle, then lowering the front triple woudl keep the bike at the same rake.

So, to me the most logical and simple answer was the tire, of course when i got the dunlops i didn't have anyway to check what size rims these would properly work on, the front size is stock.

I was concerned because you need to get your springs right and doing some sag measurements is first on the list.

Is there a chance I might need to cut my springs and install a spacer ?

Yes you can spacer adds preload, if you wack off 3-4" then that increases spring rate.

Thats just what i plan to do, I'll post my result's tonight for the sag measurements front and rear to see what you think.

The lower profile tire will be a good idea if your wheel is that wide already. I just would not want you to mask the real problems (side wall stiffness improvement) until you can solve that. Then the stiffer tire will make it even better.

I will do all of the other stuff you have listed above before going to the different tire, I will see if i can cancel the order before it ships out today.

Good as mentioned the tire would work well once you sort your springs out.

[gixerbike1]

forks springs

Pos,

I did install the new springs, i put the 20wt oil in when i replaced the seals and i still had the old springs at the time.

At that time the front end was extremely soft, now it's better but still too soft for me, if i cut the springs and add spacers will that stiffen the front end up some more ?

I cancelled the new tire and i'm going to check the sag measurements after work to see where i am.

I'll let you know what i get once i get them.

Then i'll try whatever you advise me to once i post the sag measurements.

Tommy

[gixerbike1]

gixxers.? Where??

Are you riding this GS after owning a modern sportbike? Just wondered (with your handle and sig graphic)...they do feel different, esp. whilst cornering. The older GSs while not unsafe, are nowhere as confidence-inspiring as the modern bikes, and may well feel 'flexy' when pushed in the corners, compared to a Gixxer....an altogether animal, in terms of the tires, chassis, and geometry.
Tony.

Indeed i am, I've owned 3 gixxer 750's a CBR600 a KZ700 and a CX500 and now a GS650E.

I'm diverse

[salty_monk]

I tried higher tyre pressures for a while but find it better on the freeway with slightly softer than 36-42. (I am only 160lb ish).

I ride with about 32-36 now if it's just me on there.

Dan

[posplayr]

Indeed i am, I've owned 3 gixxer 750's a CBR600 a KZ700 and a CX500 and now a GS650E.

I'm diverse

Well then don't expect any miraculous changes. The differences between radial and bias ply tiers is very significant.

I'd say my on my GS750EX which is basically stock but with Progressives and fork brace up front, with Hagon shock in the rear with Avons all around I dont like to do any heavy cornering beyond maybe 60 mph. It runs fine at 85 mph on the straights.

With my 83 1100ED, with stock 37mm forks, racetech emulators, progressive and fork brace on front with Ohlins piggybacks on the rear and Sprort Demons all around heavy corner at above 85 mph are a little scary, goes as high as you want to go straight till the wind knocks you off.

With 18" GSXR conversion 43mm forks (braces, progressive springs, emulators) and radials 170/60-18 back, 110/80-18 front (Dunlop/Avons modern stuff) with SU-145's now much more stable at 85-95 cornering. A little wollering going on and that is likely frame flex starting to have an effect.

I'm now closer to a modern bike but not there when you compare modern 180/55-17 and 120/70-17 with a real stiff frame.

Anyway, with a GS you can get a thrill at 1/2, 2/3 or 3/4 speed of a modern bike depending upon what you do to it.

[Billy Ricks]

Hate to burst your bubble but I really doubt you have a 3.75" wheel. You might have a 3.75" wide tire as stock, but the bike I see when I click on your link isn't wearing a 3.75" wheel. Wheel really means rim when you hear us talk wheels. If you look around the rim portion of the wheel you'll see the width cast into the wheel. I'm betting yours is 2.5" or less. My '85 700 only had a 2.5" wheel stock. The last 1150's only had a 3.5" wheel. Beyond 2.5" wheels they get bigger in .5" increments from what I've seen.

Going lower profile only makes the problem worse when running wider than stock tires. The sidewall gets pinched even more since it's shorter than with a higher profile tire. You're probably starting to screw up the seating area of the bead too. The more you pinch a tire the weirder the handling gets.

[posplayr]

Hate to burst your bubble but I really doubt you have a 3.75" wheel. You might have a 3.75" wide tire as stock, but the bike I see when I click on your link isn't wearing a 3.75" wheel. Wheel really means rim when you hear us talk wheels. If you look around the rim portion of the wheel you'll see the width cast into the wheel. I'm betting yours is 2.5" or less. My '85 700 only had a 2.%" wheel stock. The last 1150's only had a 3.5" wheel. Beyond 2.5" wheels they get bigger in .5" increments from what I've seen.

Going lower profile only makes the problem worse when running wider than stock tires. The sidewall gets pinched even more since it's shorter than with a higher profile tire. You're probably starting to screw up the seating area of the bead too. The more you pinch a tire the weirder the handling gets.

Thanks Billy, I was wondering about a 3.5" wide GS wheel. Anyway if you watch the video in the link you will see some sport bikes riding, but at 4:23-4:30 min into the video you will see a big full dresser trying to take some fast corners and you can see the side wall flex creating wobbling motion when he hits some slight bumps.

heavy weight on the rear with bumps causes sidewall flex induced wobble like what is seen in the video. The rear tire is slipping out a little due to higher than normal side slip angle and when it does the bike does a little lowside maneuver till the tires grabs again and sucks under the ride doing a small highside.

My theory is if the side wall did not flex as much the tire would just bite the road, when the extra weight comes down in back due to the bump, the tire would not slip out.

Of course the springs should be setup so that the front and rear stay level through this type of bump and so the exhibit more similar slip patterns and there is so lowside tendency (at least not as much).

I'm guessing any combination of mismatch would result in the same thing, but soft rear is probably worse.

http://www.thegsresources.com/_forum/showpost.php?p=1196489&postcount=1

[Billy Ricks]

Yours is good advice Jim as far as setting up sag to match at both ends. That's something he can do now to see how it helps, which it will. I think the tire needs to be correct before too much other assessment takes place. Just looking at the photo of his bike I'd say it's a 2.5" or less rim width.

[posplayr]

Yours is good advice Jim as far as setting up sag to match at both ends. I just think the tire needs to be correct before too much other assessment takes place. Just looking at the photo of his bike I'd say it's a 2.5" or less rim width.

I agree if the wheel normally takes a 110/90, i would not stick a 130/70 on it.

And yes I suggested going back to stock and setup the sag before any tire changes.

I was more throwing out what wollow really is as far as a dynamic; sort of a low amplitude low side, high side oscillation. It is a natual dynamic . I just watched a guy setting close to a track record at Isle of Mann and I see the same motion albeit at 200+ MPH.

http://www.gixxer.com/forums/showthread.php?t=263771

[Billy Ricks]

I agree if the wheel normally takes a 110/90, i would not stick a 130/70 on it.

And yes I suggested going back to stock and setup the sag before any tire changes.

I was more throwing out what wollow really is as far as a dynamic; sort of a low amplitude low side, high side oscillation. It is a natual dynamic . I just watched a guy setting close to a track record at Isle of Mann and I see the same motion albeit at 200+ MPH.

http://www.gixxer.com/forums/showthread.php?t=263771

I watched the TT too. Those guys are amazing. You see how out of shape the bikes get and they stay cool and let the bike settle down. That takes some balls to ride that island the way they do.

I think the OP is seeing a couple of things with the 130 on the rear. Triangular tire shape from being pinched leads to both. This makes the rear resist leaning over and when it does it wants to flop down off the center of the tire. When the bike comes back upright it's more abrupt than it should be out back and the suspension gets unsettled.

Then not only is the sidewall flexing but the contact area while leaned over almost becomes an extension of the sidewall from being misshapen by being pinched too much. The contact area while leaned loses it's rounded profile and gets a little flat compared to what it should be. The transition from tread area to sidewall is flatter, for want of a better word, than it should be. You lose some of the definition between the sidewall and the edge of the tire. Hope you get what I mean here.