Suspension component interchangeability

[I-K]

that's a pretty typical kawasaki set-up,way too much high n not enough low speed damping. The later model stuff is better in this respect.

Yeah, I found out about the low speed side within three weeks of my first ride. I bounced (maybe twice per second, up and down and left and right) around a ~100 km/h right hander after overtaking some cars. They probably thought it was funny. I'm glad I had the presence of mind to not whack the brakes on and drive off into the bushes.

Before you go too far... when this sort of thing starts getting talked about, even recent stock suspension is a competition-spec sniper rifle compared to the wooden club they snapped off the nearest tree and wedged in there to prop up the arse end of your bike.

With more modern stuff, the main issue is the choice of components. Replace the bargain-bin stock stuff with precision aftermarket stuff and it's sorted. On the GPX250, the problem is the unsophisticated design. Don't quote me on this, but I think the forks on them don't even have cartridges.

[Barrabob]

I put an Ohlins rear on both the 9 I sold a couple of months back and the 9 I just put on the road; the issues I looked to correct were the too-low rear ride height (they're a C1 and a C2; no rear ride height adjuster) and the unsophisticated damping, more so the compression side. The stock shock stays too rigid over bumps, but gives way too much under weight transfer due to throttle or brake application.

I see a problem here and may i say its a common one, what you are trying to do here is make the shokie do the springs job....the shokie isnt suposed to make the bike ride nice it is in fact suposed to damp the ocilations of the spring.

if your getting to much sag under power and the bike is running wide out of corners you do infact need a diferent rate spring...preload will only make the bike bang like a bastard...been there done that.

adjusting slow speed compression to try to hold the arse up will destroy your back tyre also

the heavier rate spring wont turn your bike into a bangy horrible thing if you dont use very much preload and and a bit less compression damping which you already said was harsh...dont use it the spring should only sag 30mm anyway.

and use the rebound to tame down any pogo stick tendencys.

aftermarket is usually better too.

please excuse my typos

[MiG]

On the GPX250, the problem is the unsophisticated design. Don't quote me on this, but I think the forks on them don't even have cartridges.

Hell no. They're just damper rod forks and undersprung ones at that. (About 28 mm of preload + 140 mm of travel) * 0.44 rate * 2 springs= 148 kg before bottoming out. The bike weighs about 160 kg wet. Now add me and gear and it's maybe 240 kg. What were they thinking? Soft is comfy, but then you should have more travel. I'm sure a mid life spring rate increase and revalving wouldn't affect Kawasaki's bottom line.
It's not just a matter of not being able to ride like a dick, it affects emergency braking which is pretty bloody important!

[MiG]

Hoorah for being a tightarse and not forking out for new suspension components.
I'm now riding on a GSX600F shock ($30) and chopped XJ600 springs ($50).
I tried CBR250RR springs ($40) but the diameter was too large. A dodgy angle grinder job made them fit in my forks but they'd lock up after a bit of suspension travel. = bad. I didn't want to keep grinding them smaller.

I needed to buy a $55 drill press and a $18 drill bit to enlarge the shock mounting lugs to 12 mm (the dremel + 12 mm thread tap just couldn't do it), but I got satisfaction out of it, a stiffer spring (about 1.4x), adjustable preload and adjustable rebound damping (which I utilised at Broadford to cure a wavy rear end coming into the chicane) . Unfortunately it is 15 mm shorter than stock, so the bike sits a bit low and it's still piss easy to scrape pegs, stands and exhaust pipe.

The XJ600 springs are dual rate springs and both portions were too soft, so I took the whole soft portion off and 6 coils from the hard portion, leaving 30 coils and a calculated rate of 0.66 kg/mm, which is what the racetech calculator recommends for me for street riding.

Now the rear end doesn't wallow around as much and the front is much harder to bottom out under brakes. It worked well at Broadford where it allowed me to eat the slow group under brakes and in corners

[Nanna10r]

Top stuff champ. I accidently learned something reading this thread as well..
Is that what they call a Win Win situation ?.

[Neka79]

Is that what they call a Win Win situation ?.

no mate...thats when u get blown by a girl and THEN find out she can cook!!

[goanna_38]

Unfortunately it is 15 mm shorter than stock, so the bike sits a bit low and it's still piss easy to scrape pegs, stands and exhaust pipe.

Easy fix for that. Screw the preload up till you only have aout 10-15 mm of static sag. Unless the shock is 15 mm shorter, in which case screw the preload up even more till you have no static sag. Should be fairly close to right then.

[Neka79]

after having my susp guru set up my bike last week, he advised that "1mm at the shock is almost 3mm at the wheel"..meaning that a 15mm shorter shock will drop the rear wheel ride height by 45mm,,,

i tend to believe this guy cos around here, he's god...

[MiG]

Easy fix for that. Screw the preload up till you only have aout 10-15 mm of static sag. Unless the shock is 15 mm shorter, in which case screw the preload up even more till you have no static sag. Should be fairly close to right then.

The shock is 15 mm shorter. I don't want to screw up the preload because even on the minimum setting I have about 10 mm static sag (I'll check my measurements when I get home) and the preload adjustment is bent and wonky from the previous muppet owner.

Taking away that sag to keep the ride height up is going to make the bike suck over bumps.

Time to buy a cheap stick welder?

Neka, it's true that ratio in the mechanism is far from 1 to 1. If it was just a 15 mm drop at the wheel then I probably wouldn't even notice.

[goanna_38]

Are the dog bones on your bike straight or are they offset? If they are straight and made out of aluminium all you need is a couple of bits of alloy (no scrimping on the cheap stuff (stainless is a better, just a lot harder to work with)) a hacksaw, a couple of files and an angle grinder, a drill and a bit of patience to make some new ones. Shorter dog bones will raise the rear end. If they are offset it gets a bit trickier, you also need a friend with a press and a protractor. Another friend with a laser cutter would be handy too. Wouldn't be that dear to get some cut out at a specialist profiling outfit I would imagine. If you do that go for stainless.