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Next: Brushy Mountain Chapter II
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Since: Aug 08, 2007
Posts: 10
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(Msg. 1) Posted: Wed Aug 08, 2007 9:03 am
Post subject: GSX-R 600 K4 Front forks - problems
Archived from groups: rec>motorcycles>tech (more info?)
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Hi all,
I have been changing the oil to the forks of my gsx-r 600 k4, after re-
install it again in place, went to try it and its a big mess,
initially even with the standard settings the fork looks too stiff,
but under braking the front compress fully to the end of it, try to
give more preload in the spring, and it's the same.... other thing it
makes is, in higher speeds when hit the front lever, i feel a big
vibration......
I heard this can be caused by air inside the cartridge...
Any ideas?????
Thanks
Jaime
Portugal |
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Albrecht via MotorcycleKB
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External
Since: Jun 07, 2007
Posts: 1060
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(Msg. 2) Posted: Wed Aug 08, 2007 11:56 am
Post subject: Re: GSX-R 600 K4 Front forks - problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Gixxerman wrote:
>Hi all,
>
>I have been changing the oil to the forks of my gsx-r 600 k4, after re-
>install it again in place, went to try it and its a big mess,
>initially even with the standard settings the fork looks too stiff,
>but under braking the front compress fully to the end of it, try to
>give more preload in the spring, and it's the same....
What year is your GSXR? What do you weigh? The amount of sag recommended by
the magazines may work for light weight riders, but the springs are so light
what the magazines say won't work for heavy guys.
Modern fork design relies on compression damping to resist front end dive and
a lower rate spring for good compliance.
Rider weight becomes critical when such light springs are used, and
preloading the low rate spring to reduce sag just uses up fork travel.
I got this information from www.racetech.com > sportbike > spring rates
92-93 42.6 lbs/in .762 kg/mm
97 42.6 lbs/in .762 kg/mm
98-00 ask Race Tech
01-03 43.5 lbs/in .780 kg/mm
Take the 92-93 model as an example. With two 42.6 lb/in springs, it takes 85.
2 pounds of *static* force to compress the forks one inch.
If the fork stroke is 4.4 inches, it will only take 375 pounds of force to
bottom out the fork. If the motorcycle weighs 450 pounds and you weigh 200
pounds.
375/650 = 0.576 g's.
In other words, a 1/2 g stop is going to bottom your forks.
These are Race Tech's aftermarket springs. There is a spring rate calculator
on the website.
47.5 lbs/in .85kg/mm
50.3 lbs/in .90kg/mm
53.1 lbs/in .95kg/mm
55.88 lbs/in 1.0kgmm
61.5 lbs/in 1.1kgmm
67.0 lbs/in 1.2kgmm
>other thing it
>makes is, in higher speeds when hit the front lever, i feel a big
>vibration......
It could be loose steering head or wheel bearings or a warped/misaligned
front rotor or sticky brake pads.
> I heard this can be caused by air inside the cartridge...
That's possible. Refilling a cartridge fork with oil requires careful
attention to detail to get the oil into the cartridge and the air out.
--
Message posted via MotorcycleKB.com
http://www.motorcyclekb.com/Uwe/Forums.aspx/tech/200708/1 |
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External
Since: Jan 03, 2005
Posts: 276
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(Msg. 3) Posted: Fri Aug 10, 2007 6:11 pm
Post subject: Re: GSX-R 600 K4 Front forks - problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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"Gixxerman" <gixxerman.TakeThisOut@gmail.com> wrote in message
news:1186563815.460000.231140@g4g2000hsf.googlegroups.com...
> Hi all,
>
>
> I have been changing the oil to the forks of my gsx-r 600 k4, after re-
> install it again in place, went to try it and its a big mess,
> initially even with the standard settings the fork looks too stiff,
> but under braking the front compress fully to the end of it, try to
> give more preload in the spring, and it's the same.... other thing it
> makes is, in higher speeds when hit the front lever, i feel a big
> vibration......
> I heard this can be caused by air inside the cartridge...
>
> Any ideas?????
How much oil did you use?
Did you measure volume or oil or depth to level, if latter to/from what
point?
What weight of oil did you use?
--
Dave
ex Motorcycle Maintenance Workshop
http://tinyurl.com/4mhaw >> Stay informed about: GSX-R 600 K4 Front forks - problems |
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External
Since: Aug 08, 2007
Posts: 10
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(Msg. 4) Posted: Mon Aug 13, 2007 8:25 am
Post subject: Re: GSX-R 600 K4 Front forks - problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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On 10 Ago, 18:11, "Dave Emerson" <Dave_dot_Emer....TakeThisOut@LineOne.net> wrote:
> "Gixxerman" <gixxer....TakeThisOut@gmail.com> wrote in message
>
> news:1186563815.460000.231140@g4g2000hsf.googlegroups.com...
>
> > Hi all,
>
> > I have been changing the oil to the forks of my gsx-r 600 k4, after re-
> > install it again in place, went to try it and its a big mess,
> > initially even with the standard settings the fork looks too stiff,
> > but under braking the front compress fully to the end of it, try to
> > give more preload in the spring, and it's the same.... other thing it
> > makes is, in higher speeds when hit the front lever, i feel a big
> > vibration......
> > I heard this can be caused by air inside the cartridge...
>
> > Any ideas?????
>
> How much oil did you use?
>
> Did you measure volume or oil or depth to level, if latter to/from what
> point?
>
> What weight of oil did you use?
>
> --
> Dave
> ex Motorcycle Maintenance Workshophttp://tinyurl.com/4mhaw
In the beginning i put a little bit under the recommended quantitty,
but now i have refill it, and have the exact amount especify in the
service manual.
After some tests, the front is now working ok, but is still juddering
when i brake harder under highest speeds, it guet's better when i
close the rebound, but then it becames to stiff.
Jaime >> Stay informed about: GSX-R 600 K4 Front forks - problems |
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External
Since: Aug 08, 2007
Posts: 10
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(Msg. 5) Posted: Mon Aug 13, 2007 8:27 am
Post subject: Re: GSX-R 600 K4 Front forks - problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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On 13 Ago, 09:25, Gixxerman <gixxer....TakeThisOut@gmail.com> wrote:
> On 10 Ago, 18:11, "Dave Emerson" <Dave_dot_Emer....TakeThisOut@LineOne.net> wrote:
>
>
>
>
>
> > "Gixxerman" <gixxer....TakeThisOut@gmail.com> wrote in message
>
> >news:1186563815.460000.231140@g4g2000hsf.googlegroups.com...
>
> > > Hi all,
>
> > > I have been changing the oil to the forks of my gsx-r 600 k4, after re-
> > > install it again in place, went to try it and its a big mess,
> > > initially even with the standard settings the fork looks too stiff,
> > > but under braking the front compress fully to the end of it, try to
> > > give more preload in the spring, and it's the same.... other thing it
> > > makes is, in higher speeds when hit the front lever, i feel a big
> > > vibration......
> > > I heard this can be caused by air inside the cartridge...
>
> > > Any ideas?????
>
> > How much oil did you use?
>
> > Did you measure volume or oil or depth to level, if latter to/from what
> > point?
>
> > What weight of oil did you use?
>
> > --
> > Dave
> > ex Motorcycle Maintenance Workshophttp://tinyurl.com/4mhaw
>
> In the beginning i put a little bit under the recommended quantitty,
> but now i have refill it, and have the exact amount especify in the
> service manual.
>
> After some tests, the front is now working ok, but is still juddering
> when i brake harder under highest speeds, it guet's better when i
> close the rebound, but then it becames to stiff.
>
> Jaime- Ocultar texto citado -
>
> - Mostrar texto citado -
Forgot to tell,
I'm using Motorex Oil 5w as specified in the service manual
479 ml in each side of the fork... >> Stay informed about: GSX-R 600 K4 Front forks - problems |
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External
Since: Aug 08, 2007
Posts: 10
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(Msg. 6) Posted: Mon Aug 13, 2007 1:43 pm
Post subject: Re: GSX-R 600 K4 Front forks - problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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On 13 Ago, 15:40, "Albrecht via MotorcycleKB.com" <u33665@uwe> wrote:
> Gixxerman wrote:
> >After some tests, the front is now working ok, but is still juddering
> >when i brake harder under highest speeds, it guet's better when i
> >close the rebound, but then it becames to stiff.
>
> Dude...
>
> If the front tire contact patch is chattering on the road surface, you need
> to
> decrease the *compression* damping, not increase the rebound damping.
>
> But you have to have the correct springs for your weight.
>
> You would increase the rebound damping if the fork was wallowing at low
> frequency. Too much rebound damping with light springs can cause the fork to
> "pump down" and become rigid when it bottoms.
>
> I asked you before: WHAT DO YOU WEIGH? Have you been to thewww.racetech.com
> site to use their rider weight spring calculator program?
>
> --
> Message posted via MotorcycleKB.comhttp://www.motorcyclekb.com/Uwe/Forums..aspx/tech/200708/1
I haven't been to the www.racetech.com site, and my weight is 83 kg's
before i change the oil, the forks were working ok with the std
settings, after i change the oil they arenīt  ,
Probably to reduce the compression damping i have to add a little bit
more oil, because the front is still diving a lot, after that will try
it again to see how it feels, as soon the front is ok in matters of
compression, i will start to find the perfect rebound setting.
Jaime >> Stay informed about: GSX-R 600 K4 Front forks - problems |
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Albrecht via MotorcycleKB
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External
Since: Jun 07, 2007
Posts: 1060
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(Msg. 7) Posted: Mon Aug 13, 2007 2:40 pm
Post subject: Re: GSX-R 600 K4 Front forks - problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Gixxerman wrote:
>After some tests, the front is now working ok, but is still juddering
>when i brake harder under highest speeds, it guet's better when i
>close the rebound, but then it becames to stiff.
Dude...
If the front tire contact patch is chattering on the road surface, you need
to
decrease the *compression* damping, not increase the rebound damping.
But you have to have the correct springs for your weight.
You would increase the rebound damping if the fork was wallowing at low
frequency. Too much rebound damping with light springs can cause the fork to
"pump down" and become rigid when it bottoms.
I asked you before: WHAT DO YOU WEIGH? Have you been to the www.racetech.com
site to use their rider weight spring calculator program?
--
Message posted via MotorcycleKB.com
http://www.motorcyclekb.com/Uwe/Forums.aspx/tech/200708/1 >> Stay informed about: GSX-R 600 K4 Front forks - problems |
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Albrecht via MotorcycleKB
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External
Since: Jun 07, 2007
Posts: 1060
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(Msg. 8) Posted: Mon Aug 13, 2007 4:57 pm
Post subject: Re: GSX-R 600 K4 Front forks - problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Gixxerman wrote:
>I haven't been to the www.racetech.com site, and my weight is 83 kg's
Stock spring is about .76 kg/mm or .78 kg/mm
For your weight, Racetech offers .85kg/mm for street riding, and .95kg for
racing
>before i change the oil, the forks were working ok with the std
>settings, after i change the oil they aren?t ,
Like you said before, you might have gotten air into the system. When
refilling flooded leg cartridge
forks, you have to work the air out of the cartridges by slowly stroking the
forks about 10 times through
less than full stroke.
>
>Probably to reduce the compression damping i have to add a little bit
>more oil, because the front is still diving a lot,
That remark makes no sense whatever to me. Forcing the fork oil through the
shim stacks assists the
fork springs while the forks are compressing. Cpmpression damping is
accomplished by the resistance
of oil flow through the shim stack, up to the point where they bend and blow
off pressure. Adding
oil increases the spring affect of the air inside the tubes and that
pressurized air resists compression.
But air has little damping effect under pressure achievable inside a fork,
and extra oil in the fork does nothing except reduce air volume.
>after that will try
>it again to see how it feels, as soon the front is ok in matters of
>compression, i will start to find the perfect rebound setting.
You need enough rebound damping to control fork movement so the bike steers
correctly. A competition fork
set up for a smooth race track doesn't need a lot of rebound damping, it just
needs to respond to small bumps
rapidly over and over.
If you are riding back roads in the country, you may need more rebound
damping for better control over
rolling terrain where you're riding a lot slower, but the ups and downs are
large.
--
Message posted via MotorcycleKB.com
http://www.motorcyclekb.com/Uwe/Forums.aspx/tech/200708/1 >> Stay informed about: GSX-R 600 K4 Front forks - problems |
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External
Since: Aug 08, 2007
Posts: 10
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(Msg. 9) Posted: Tue Aug 14, 2007 4:33 am
Post subject: Re: GSX-R 600 K4 Front forks - problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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On Aug 13, 5:57 pm, "Albrecht via MotorcycleKB.com" <u33665@uwe>
wrote:
> Gixxerman wrote:
> >I haven't been to thewww.racetech.comsite, and my weight is 83 kg's
>
> Stock spring is about .76 kg/mm or .78 kg/mm
>
> For your weight, Racetech offers .85kg/mm for street riding, and .95kg for
> racing
>
> >before i change the oil, the forks were working ok with the std
> >settings, after i change the oil they aren?t ,
>
> Like you said before, you might have gotten air into the system. When
> refilling flooded leg cartridge
> forks, you have to work the air out of the cartridges by slowly stroking the
> forks about 10 times through
> less than full stroke.
>
>
>
> >Probably to reduce the compression damping i have to add a little bit
> >more oil, because the front is still diving a lot,
>
> That remark makes no sense whatever to me. Forcing the fork oil through the
> shim stacks assists the
> fork springs while the forks are compressing. Cpmpression damping is
> accomplished by the resistance
> of oil flow through the shim stack, up to the point where they bend and blow
> off pressure. Adding
> oil increases the spring affect of the air inside the tubes and that
> pressurized air resists compression.
>
> But air has little damping effect under pressure achievable inside a fork,
> and extra oil in the fork does nothing except reduce air volume.
>
> >after that will try
> >it again to see how it feels, as soon the front is ok in matters of
> >compression, i will start to find the perfect rebound setting.
>
> You need enough rebound damping to control fork movement so the bike steers
> correctly. A competition fork
> set up for a smooth race track doesn't need a lot of rebound damping, it just
> needs to respond to small bumps
> rapidly over and over.
>
> If you are riding back roads in the country, you may need more rebound
> damping for better control over
> rolling terrain where you're riding a lot slower, but the ups and downs are
> large.
>
> --
> Message posted via MotorcycleKB.comhttp://www.motorcyclekb.com/Uwe/Forums.aspx/tech/200708/1
OK,
Thanks for the info
i will make that, then after try it i will write here my impressions.
Cheers
Jaime >> Stay informed about: GSX-R 600 K4 Front forks - problems |
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External
Since: Aug 08, 2007
Posts: 10
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(Msg. 10) Posted: Tue Sep 25, 2007 6:59 am
Post subject: Re: GSX-R 600 K4 Front forks - problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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So here i'am, to make the latest update.
I've changed the brake discs and pads, but still have the vibration
under braking, the funny thing is if i go at 150 km/h and brake hard,
the bike goes very smooth, as soon as a get to the 80km/h the front
starts to vibe, after the speed goes under 70km/h the bike goes smooth
again....
Next step is tho try a different wheel to see if is bearings problems,
or tire.
Best Regards
Jaime
> > --
> > Message posted via MotorcycleKB.comhttp://www.motorcyclekb.com/Uwe/Forums.aspx/tech/200708/1
>
> OK,
>
> Thanks for the info
>
> i will make that, then after try it i will write here my impressions.
>
> Cheers
> Jaime- Ocultar texto citado -
>
> - Mostrar texto citado - >> Stay informed about: GSX-R 600 K4 Front forks - problems |
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External
Since: Sep 24, 2007
Posts: 38
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(Msg. 11) Posted: Tue Sep 25, 2007 7:26 am
Post subject: Re: GSX-R 600 K4 Front forks - problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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On Sep 25, 6:59?am, Gixxerman <gixxer....RemoveThis@gmail.com> wrote:
> I've changed the brake discs and pads, but still have the vibration
> under braking, the funny thing is if i go at 150 km/h and brake hard,
> the bike goes very smooth, as soon as a get to the 80km/h the front
> starts to vibe, after the speed goes under 70km/h the bike goes smooth
> again....
Have you re-torqued the steering head bearings recently? >> Stay informed about: GSX-R 600 K4 Front forks - problems |
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External
Since: Aug 08, 2007
Posts: 10
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(Msg. 12) Posted: Tue Sep 25, 2007 11:39 am
Post subject: Re: GSX-R 600 K4 Front forks - problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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On 25 Set, 15:26, ~ <Rhiann... RemoveThis @gmail.com> wrote:
> On Sep 25, 6:59?am, Gixxerman <gixxer... RemoveThis @gmail.com> wrote:
>
> > I've changed the brake discs and pads, but still have the vibration
> > under braking, the funny thing is if i go at 150 km/h and brake hard,
> > the bike goes very smooth, as soon as a get to the 80km/h the front
> > starts to vibe, after the speed goes under 70km/h the bike goes smooth
> > again....
>
> Have you re-torqued the steering head bearings recently?
nope, and that is also a good idea to do that >> Stay informed about: GSX-R 600 K4 Front forks - problems |
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External
Since: Aug 08, 2007
Posts: 10
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(Msg. 13) Posted: Tue Oct 16, 2007 9:32 am
Post subject: Re: GSX-R 600 K4 Front forks - problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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On 25 Set, 16:10, Gixxerman <gixxer... RemoveThis @gmail.com> wrote:
> On 25 Set, 15:26, ~ <Rhiann... RemoveThis @gmail.com> wrote:
>
> > On Sep 25, 6:59?am, Gixxerman <gixxer... RemoveThis @gmail.com> wrote:
>
> > > I've changed the brake discs and pads, but still have the vibration
> > > under braking, the funny thing is if i go at 150 km/h and brake hard,
> > > the bike goes very smooth, as soon as a get to the 80km/h thefront
> > > starts to vibe, after the speed goes under 70km/h the bike goes smooth
> > > again....
>
> > Have you re-torqued the steering head bearings recently?
>
> nope, and that is also a good idea to do that
After re-torqued the steering head bearings, and change the front
wheel bearing, the bike keeps doing the same vibration. a go now try
with a different wheel to check, if it's not the wheel.
Cheers
Jaime >> Stay informed about: GSX-R 600 K4 Front forks - problems |
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External
Since: Aug 08, 2007
Posts: 10
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(Msg. 14) Posted: Wed Oct 17, 2007 7:14 am
Post subject: Re: GSX-R 600 K4 Front forks - problems [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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On 16 Out, 10:32, Gixxerman <gixxer... RemoveThis @gmail.com> wrote:
> On 25 Set, 16:10, Gixxerman <gixxer... RemoveThis @gmail.com> wrote:
>
> > On 25 Set, 15:26, ~ <Rhiann... RemoveThis @gmail.com> wrote:
>
> > > On Sep 25, 6:59?am, Gixxerman <gixxer... RemoveThis @gmail.com> wrote:
>
> > > > I've changed the brake discs and pads, but still have the vibration
> > > > under braking, the funny thing is if i go at 150 km/h and brake hard,
> > > > the bike goes very smooth, as soon as a get to the 80km/h thefront
> > > > starts to vibe, after the speed goes under 70km/h the bike goes smooth
> > > > again....
>
> > > Have you re-torqued the steering head bearings recently?
>
> > nope, and that is also a good idea to do that
>
> After re-torqued the steering head bearings, and change the front
> wheel bearing, the bike keeps doing the same vibration. a go now try
> with a different wheel to check, if it's not the wheel.
>
> Cheers
> Jaime
I All, it's me again, changing the front wheel, produce no effect in
the vibration of the front, the vibe is still there when braking,
could it be the suspension.
Cheers
Jaime
Portugal >> Stay informed about: GSX-R 600 K4 Front forks - problems |
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