GPX600R unsettled into corners and hard over bumps!

[Shifty]

My GPX is pretty long in the tooth, and could use a bit of love in the suspension department. Interestingly, despite the age and kms on the bike, the rear end is absolutely bone-shattering over bumps.

The front end, by contrast, seems a little unsettled on corner entry (as my cousing said, "it looks bloody unsafe"). I was hoping someone here might have had some experience with one of these.. information regarding what has been done, costs, or even general bike suspension information would be great.

I'm from the world of car racing, so telescopic forks and swingarms are a little like black magic at the moment

[strutto]

Off topic for a sec...

Shifty, as in Shifty from OCAUMC, as in Shifty from PF, as in Shifty from Toymods with the Supra?

Our paths have crossed previously... Spooky...

[Shifty]

Yeah, nothing like a bit of consistency. I don't use forums where I can't have my name

[Smitty]

Shifty
the old girl a bit unsteady on her feet..???

first things to check -
steering head bearings oK?..not too loose or tight
front wheel bearings ok?..no slop
front wheel axle tight...?
no leaks from the fork seals?
rear swing arm not sloppy, bearings not stuffed?
rear wheel aligned in swing arm?
rear wheel tight?
chain ok and tensioned correctly?
rear unitrak suspension links ok and lubed up?
rear shock not loose ..?

all ok? yep! so next
lets get new oil in the forks
why? see my post here....
http://www.ksrc-au.com/phpBB2/viewtopic.php?t=2750
that black crap called used fork oil is not gunna help
so I suggest you get some new fork oil ..try a slightly heavier oil
than recommended say 10w (std is 5w) and try it.
think you will find the front improves

next....
the rear suspension!
if the swing arm is ok and the unitrak links ok
you are left with the rear shock absorber
they are an air/gas unit..that either work or don't
and if they don't work, you have basically no suspension on the rear of the
bike..it will be rock hard (sound familiar?)
and
there is one simple test for the unit
get out the pushbike pump and pump the unit up to 15psi
(connector is on the rh side of the bike and comes out thru the frame)
then set the shocker to max stiffness..
pull out the adjuster link as far as it will go, then sit on the bike and bounce up and down
bike rock hard?? shock is stuffed and you need a new one
bike bounces? shock is ok but make sure you keep air in it
It is likely that due to age the shock is stuffed
and the OE Kwaka unit is not the best, an Ohlins shock with spring is better
but will cost you.

You may need a manual to do or check out some of the above
think you will find 2ndhand manuals on eBay pretty cheap
and of course an amount of mechanical knowledge
If you don't wanna do the dirty work, hand it to a workshop to do
(there are some safety issues with some of the above, better
to be safe than sorry)

hth

cheers

[ttc]

Cripes, I didn't realise was the same Shifty too, had no idea you had a Kwaka
Welcome

Another queenslander cos we rock And you'll find this forum is like no other, we're usually nice to each other, no flaming here (well unless it's warranted anyway )

[omen_child]

Sounds like you've got a bit too much preload (or too stiff a spring) and too little damping.

[Smitty]

Sounds like you've got a bit too much preload (or too stiff a spring) and too little damping.

ummm
don't think so
the old GPx has no adjustment on the front forks at all
(you use oil weight and height to stiffen it)
and only a compression adjuster on the rear shock (NO spring )

nothing like your 7R


cheers

[Shifty]

heaps of stuff

Smitty, excellent reply, thanks for your help. Most of the common sense items I have already checked... no leaks, nothing loose, nothing visibly shagged, and no rattles (except my teeth over bumps)!

The rear concerns me more than anything, the front I can deal with - if anything it teaches me to take it easy into corners!

Going shopping on Friday for some new gear (boots and back protector, yay!), then scrabbling up the money for suspension.

Cripes, I didn't realise was the same Shifty too, had no idea you had a Kwaka

It seems my name is well known in revhead circles. And of course I have a Kawasaki, I'm cool.... besides, I want a Z1000 when I grow up