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so ive read past posts about speed over 100mph and i new my bike started vibrating before i could get to 80, so i put 10psi of air in the frt shocks and 40psi in the frt/r tires and took it for a test ride today. at about 75-80mph i noticed the frt shocks abnormally jumping up and down causing my vibrating issue. i thought a little more air pressure in the shocks may cure it to no avail. my tire is 5 yrs or more old with 1000mi on it. everything in the front suspension is OEM set at the factory. i need some ideas. thanx
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Last edited by mjpxs11sh; 05-11-2012, 10:47 PM.Max
81 XS1100SH Black Beast Mutt
Kerker 4/1
stock carbs and air box.
78 headlite, handle bars,
1 set of ea-160/85mph guages,
crash bars, cruise control
Other 2 Wheelers
78 XS1100E jet kit, Kerker 4/1, air pods, jet kit-RIP
94 CBR1000F jet kit,Two Bros pipe, K&N Filter -
Time to re-ballance the tires.Slow down and enjoy life. If you are in that much of a hurry, you should have left eariler.
Current rides:
80 XS1100SG
82 JX1100
83 Venture Royale
86 V-Max -
Balance?
Are you saying not to put dice on your valve stems? Had mine up to 200 kmph on a regular basis and no wobble YET.Originally posted by mlew View Post
Some make 'em, most just make payments on 'em!
1978 XS 1100E
Vance & Hines Slip on Straight Shot Exhaust
K & N Air filter
Home built forward controls
Vulcan Mustang seat
A little chopped
http://s812.photobucket.com/albums/zz42/Brad_099/Comment
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after some thought back into history, i remember i had the frt tire changed 10yrs or so ago, not 5, for the problem because the tire was cupped and then it was put into storage and not tested at that speed. now that i got it back on the street i find the issue wasnt ever corrected. so im not sure its a balance issue. it seems the frt end hops. is that the tire? the only thing i can see are the forks hopping.Max
81 XS1100SH Black Beast Mutt
Kerker 4/1
stock carbs and air box.
78 headlite, handle bars,
1 set of ea-160/85mph guages,
crash bars, cruise control
Other 2 Wheelers
78 XS1100E jet kit, Kerker 4/1, air pods, jet kit-RIP
94 CBR1000F jet kit,Two Bros pipe, K&N FilterComment
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Well, there's not a whole lot that can be wrong up there... Lets think about this logically, did you do any work to your forks other then add air? Its not like you disassembled them then noticed the problem right? Rather than blaming the suspension you first need to rule out some of the obvious items like tire balance, then make sure the tire bead is seated in the rim properly (concentric). Sometimes the simplest things are the most over looked. If that doesn't help, you could try some of those dyna beads. If the tire really is 10 years old, I would consider getting a new one. Mine is going on 3 yrs and is showing slight weather checking in the bottom of the tread, I cant imagine what it would look like at 5 or 10 years!Last edited by WMarshy; 05-12-2012, 01:19 AM.'79 XS11 F
Stock except K&N
'79 XS11 SF
Stock, no title.
'84 Chevy K-10 "Big Blue"
GM 350, Muncie SM465, NP208, GM 10 Bolt with 3.42gears turnin 31x10.5 Baja Claws
"What they do have is an implacable, unrelenting presence and movement that bespeaks massive power lurking behind paint and chrome. They don't wail like a screeching ninja, the don't rumble like a harley. They just growl like a spactic, stressed out badger waiting to rip your face off and eat your soul." Trainzz~RIP~Comment
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10 year old tire, get a new one and start fresh!Nathan
KD9ARL
μολὼν λαβέ
1978 XS1100E
K&N Filter
#45 pilot Jet, #137.5 Main Jet
OEM Exhaust
ATK Fork Brace
LED Dash lights
Ammeter, Oil Pressure, Oil Temp, and Volt Meters
Green Monster Coils
SS Brake Lines
Vision 550 Auto Tensioner
In any moment of decision the best thing you can do is the right thing, the next best thing is the wrong thing, and the worst thing you can do is nothing.
Theodore RooseveltComment
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Rubber does lose some of its "elasticity" over the years, so a 10 yr old tire is typically not as soft and may not give good traction. It also may pop on the first good bump due to it not being able to "bend" or give with that movement.
As to the hopping of the front wheel, I would look at the entire wheel assembly. It is the only part rotating and able to cause the hopping (unless your riding on a really rough road
) Easiest place to start is the tire, since it is long overdue for replacement anyway. May also look at the wheel bearings, see if there is any movement in those.
Life is what happens while your planning everything else!
When your work speaks for itself, don't interrupt.
81 XS1100 Special - Humpty Dumpty
80 XS1100 Special - Project Resurrection
Previously owned
93 GSX600F
80 XS1100 Special - Ruby
81 XS1100 Special
81 CB750 C
80 CB750 C
78 XS750Comment
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+1 Your gonna hurt yourself with that old tire. On the front especially, the rear isn't so bad but if that front blows your going down guaranteed.Originally posted by natemoen View PostGreg
Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”
― Albert Einstein
80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.
The list changes.
Comment
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I bought some spare rims and one of them had a very nice looking tire on it. Aired it up and sprayed it down with soapy water and it held air great. Picked it up and tried to bounce it a bit to see what it did....nothing. Sounded like I dropped a piece of wood on the ground. Manufacture date was back in 2003, so it was younger than your tire even but it WILL NOT get used!Nathan
KD9ARL
μολὼν λαβέ
1978 XS1100E
K&N Filter
#45 pilot Jet, #137.5 Main Jet
OEM Exhaust
ATK Fork Brace
LED Dash lights
Ammeter, Oil Pressure, Oil Temp, and Volt Meters
Green Monster Coils
SS Brake Lines
Vision 550 Auto Tensioner
In any moment of decision the best thing you can do is the right thing, the next best thing is the wrong thing, and the worst thing you can do is nothing.
Theodore RooseveltComment
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allright then, i guess the wheel and tire are suspect so ill have 2 frt tires hardly worn and unusable. no, i didnt do anything to the forks, just had the frt tire replaced for the issue. thanx all for the replys!Max
81 XS1100SH Black Beast Mutt
Kerker 4/1
stock carbs and air box.
78 headlite, handle bars,
1 set of ea-160/85mph guages,
crash bars, cruise control
Other 2 Wheelers
78 XS1100E jet kit, Kerker 4/1, air pods, jet kit-RIP
94 CBR1000F jet kit,Two Bros pipe, K&N FilterComment
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Well, looks like if the tires are actually older that U first remembered, plus sounds like it sat for a fairly extended time, I would imagine that front tire has a permanent flat spot. At there age, somethin' ought to be tellin' you to replace them with new tars. Likely problem solved........just sayin'...........81H Venturer1100 "The Bentley" (on steroids) 97 Yamaha YZ250(age reducer) 92 Honda ST1100 "Twisty"(touring rocket) Age is relative to the number of seconds counted 'airing' out an 85ft. table-top.Comment
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i hear ya. it just didnt make sense that i dont feel any issues till im at that speed. i know with car tires any vibration at 35-50 is a tire balance and anything at 70-80 is a bad wheel. i just got a Bridgestone for the rear. i should have got one for the front. i was just tired of buying frts when theres no wear. oh well, gotta bite the bullet. im just glad thats my last issue and shes back on the road.Max
81 XS1100SH Black Beast Mutt
Kerker 4/1
stock carbs and air box.
78 headlite, handle bars,
1 set of ea-160/85mph guages,
crash bars, cruise control
Other 2 Wheelers
78 XS1100E jet kit, Kerker 4/1, air pods, jet kit-RIP
94 CBR1000F jet kit,Two Bros pipe, K&N FilterComment
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I dont think you can make the assumption that vibration at 40=tire balance and 80=wheel. Vibration occurs in orders of frequency so it is expected that a noticeable vibration at 30 will re-apear at 60...Originally posted by mjpxs11sh View Post
"The nature of the rotating items is that the vibrations occur at multiples and submultiples of the rotational speed. For example if the shaft is rotating at 3600rpm, which is 60 Hz, then we would expect to see responses at multiples of this frequency. These multiples are the orders (or harmonics in musical terms). First order is a frequency which is the same as the shaft rotational speed. In our example this is 60 Hz. The third order would be 3 * 60 = 180 Hz." "...first order is always at the shaft speed; second order is always twice shaft speed and so on." http://blog.prosig.com/2002/02/03/fr...-hertz-orders/'79 XS11 F
Stock except K&N
'79 XS11 SF
Stock, no title.
'84 Chevy K-10 "Big Blue"
GM 350, Muncie SM465, NP208, GM 10 Bolt with 3.42gears turnin 31x10.5 Baja Claws
"What they do have is an implacable, unrelenting presence and movement that bespeaks massive power lurking behind paint and chrome. They don't wail like a screeching ninja, the don't rumble like a harley. They just growl like a spactic, stressed out badger waiting to rip your face off and eat your soul." Trainzz~RIP~Comment
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Best urban myth I've heard in awhile..............Originally posted by mjpxs11sh View Post81H Venturer1100 "The Bentley" (on steroids) 97 Yamaha YZ250(age reducer) 92 Honda ST1100 "Twisty"(touring rocket) Age is relative to the number of seconds counted 'airing' out an 85ft. table-top.Comment
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