Adjusting GSXR suspension, (on an SV).

[chakraist]

So as some of you may know, I bought AndyB's bike and it has a delicious front end that simply smells of excellence. Anyways, I bottom out the fork under braking (I'm almost twice Andy's weight!) and I downloaded a manual for the GSXR750 which the front end is from and it basically told me to adjust the left hand preload thingy. I was under the impression that you have to adjust both, I believe it's a K4/5 front end.

I'm basically an idiot so this is why I'm asking, I did also search and there's lots about suspension settings but not much about how to actually adjust the suspension. Anybody with the front end swap or a gsxr feel like helping out?

Nostrovey!
Conrad

[neio79]

IIRC, if its like my 6R only one side adjusts the preload the other side is for rebound or damping , and again on the top all the twiddly and turny things do different bits.

Take it to a suspension set up place and for 30 ish quid they will set it up for you.

[sv_rory]

i got a gsxr 750 front end on mine and would like to know how to adjust it, the lady i got my bike from said it was set up for her but i havent got a clue where to find out how to do it

[neio79]

suspension set up on modern sports bikes with full adjustment is a black art, so my advice would be get someone who knows what they are doing to set it up for you. As if you get it wrong its going to make the bike handle wrong.

[andyb]

It's got K3 forks mate. I'm no expert and left if the same when I fitted them as they were OPk but I think you have to adjust both sides using the little blue nut on the top of the forks. The comp/damping are separate screws at the top and bottom of the forks.

[yorkie_chris]

http://www.suzuki-gb.co.uk/uploads/240_gsxr750%20top%20yoke%201.jpg

The blue bit is the preload adjuster, the small screw in the middle is for rebound.



Right then.... IMO ... and presuming the slider leaves a gap at full compression between the dust seal and bottom casting.

Stick 2 tie wraps round a fork leg one above the other, they don't need to be super-tight just snug.

Go for a ride, they'll be sat at the bottom of the fork leg, increase the preload, do everything you do to one fork leg, to the other.
After each adjustment, move the top tie wrap back up the leg, and keep doing this.

The value I've heard is to get 10mm of travel left before bottoming out under usual riding.

If your forks are bottoming out now, then when you get it right, the bottom cable tie will be at the "bottomed out" position, so just look at the gap between them.

This worked fine on my RWU gixxer forks, but does depend on there being a gap between the dust seal and bottom casting at full compression on the USD forks.

Suspension setup isn't a black art at all, but it does pay to make little adjustments, figure out what's different and keep a log of what settings.

[chakraist]

Cheers guys for that, I'll give it a go tomorrow.

[21QUEST]

Hi, first question I tend to ask folks is "how do you know it is bottoming". Always sounds like a silly question but sometimes what feels like bottoming, is not....unless yo have definitely checked it out...ie cable tie as Chris says.


Anyhoo not a suspension expert but I'll try my best ;).


I'll suggest you set the sag properly first. Set it with all the adjusters fully wound(softtest)....both compression(flat slotted thingy at bottom of forks) and rebound(flat slotted thingy at top of forks). careful you don't snap them off hehe.
You can set the front sag on your own if yo have access to a wall :) and a cable tie. I like to use 2.5mm or 5mm wide cable ties).
I think the Suzuki advertises stroke on the forks is 120mm but you can do a google check.


So cable tie on stanchion just tight enough that it stays on....don't want it too tight. Get dressed and put bike next to a wall so you can seat on it and balance it up right and get into you usual ridig position...don't forget to keep one hand on the wall to support the bike lol .


Before you get on the bike(bike on stand stand), push the cable tie right up to the dust seal, then lift up gently and climb on without an unnecessary compression of the forks. Leave the side stand down and obviously to the outside of the wall.


So as said above, down to usual riding position, hang in the position for a few seconds , then slowly put bike to rest on the side stand(which you left down ;) ).


Get a tape measure or rule and measure the distance from the bottom end of chrome stanchion to the top part of the cable tie. Assumming the stroke of the forks is 120mm, you are looking for an initial figure of 85mm ie 120mm minus 85mm giving you a sag fiigure of 35mm . If figure you get is more than 35mm , turn the prelaod adjuster, which is the Blue 22mm spanner jobbie thingy(technical term) to next line.
If out still, adjust half way between two lines...... which ever way you need to go and take measurement again. Repeat until you get your base line figure of 35mm



For the adjusters, now wind them all in and count back 1.5 turns out for the compression and 1.25 turns out for the rebound. Again be carefl not to damage them. Slowy and stop once you feel it errr come to a stop or you any resistanc.


Rear is obviously a bit trickier without a someone to help but for starters you can just set the bike sag(no rider) for that. I'm assumming you have the standard shock(?). For the rear , you really need to unload the rear(normal paddock stand is no good). measure from middle of rear spindle to somewhere on subframe or body work. make note of that figure.


The put bike up right and measure same two points. If on the original shock,, hopefull you can adjust to between 5mm and 10mm.


After getting your initial baseline , you now have to ride it and adjust depending on what you feel etc........here is where Neio79s cmment on perhaps leaving it to the pro if you are not sure comes in ;).

Where about are you?......as depending on where you are, I could be tempted to......... ;)
Errr, hope all the waffle made some sense. Like I said, happy to help out depending on where you are.



Ben

[northwind]

21Quest knows stuff. But, if it was me and I was too heavy for the springs, I'd be taking it to a pro and getting them swapped (which is possible to do DIY with just muscle and cable ties with those forks) and revalved to suit(which isn't so simple, I wouldn't even try myself). That's a really good setup, it's kind of a shame to compromise on it.

I'm lucky, I weigh as much as an action man so I was fine with the standard springs. Though with my current forks, they're oversprung for me :rolleyes:

[21QUEST]

You make very good points Northy but I would still prolly say, not yet.

We can still get real good compromise with the standard bit, I'd say....have you seen the size of some of those Sunday warriors :p .
Plus spending good money with suspension companies(even or should that be, especially the Big well known ones lol) doesn't always pay the huge dividends they should.....okay I'm being a touch cynical about the companies but not without reason lol

Depending on when the fork oil was last changed, it'll be a good idea to do that first anyways. Perhaps springs too and then go from there. I'll do the oil and spring change for a bottle of shandy :eek:.

chakraist, how much did you say you weigh?


Ben

[northwind]

have you seen the size of some of those Sunday warriors :p .

What, the ones convinced that their bikes handle amazingly, when in fact they're bending under the weight and can barely go round a roundabout? :) Good point on the suspension companies though, too many will take liberties knowing that, well, they can get away with it because most of us know nothing about suspension!

[chakraist]

I weigh a shade over 17 stone, just under 18 with gear. The main problem I was having was looking at the forks, there are two sets of adjusters with I believe opposite turning compression and damping. I'll check it all over tomorrow and see how it goes, may have to invest in cable ties! Cheers again guys. When I brake hard, the front end dips a fair amount (although much less than stock) and sort of bounces up and down a little bit, vibrating the bars under heavy braking.

[Red Herring]

Just a thought, have you checked the run out on the discs?

[plowsie]

I weigh a shade over 17 stone, just under 18 with gear.
Lucky you!

I'd take it to the proffesionals for a few bob mate!

[andyb]

Just a thought, have you checked the run out on the discs?

This was checked during the MOT and was all OK. I have to say I never had any sort of vibration under braking but your weight may show something up more than mine! What are you doing to it, racing it to work??? :)

[chakraist]

Basically yes, well, I like to brake quite hard, totally within limits but it's nice to go reasonably quick.

[chakraist]

Okay, so I had a play today and got the following:

Rider sag 33.5mm with 3 full turns of preload less than the max - the forks are about 11mm out of the top of the yoke.

Rebound is set to 2 full turns - rebound takes less than a second and doesn't shoot up during corners.

Compression is at 1.75 turns - with this like that I have about 12-14mm of travel left on the fork (and I was braking hard down from 50 leaning fully forwards on the bike, got some funny looks).

I know my rebound is probably way out from what you guys would suggest but I like it that way and it seems to be fine over bumps as well as round corners. It instantly feels twice as good to ride, much more planted and no huge vibrations under braking, the brakes have a lot more feel to them now as well.

Thanks for all the help from everyone, much obliged.

[Racerx]

Might or might not be interesting to people here but Pro Action in Pontefract, West Yorks only charged me ?220 for a rear ohlins revalving and a factory fork kit installing in my race supermoto.

I'm confident it would be a lot cheaper just for new springs and valving to suit your weight.

The guy who runs it has been doing motorcross and supermoto bikes for years and is now doing road bikes. Even supporting a few guys over on the isle of man.

Its a pro setup but without all the usual bull sh!t you get from you know who. If your not happy with the setup he'll sort it out without an extra cost.

[andyb]

Glad you got it set-up OK for your weight. I still need to set-up my new bike properly!!

[Red Herring]

If you have to much rebound damping then the forks will "pump down" under prolonged braking (or a long bumpy stretch). "less than a second" still sounds an awfully long time for them to return. Generally speaking for road riding I always try to run as soft as I can on the spring (stiff enough to stop bottoming out, yet not topping out), then control it with the damping. When you pump the forks they should compress and return smoothly and evenly. If they spring back past the static point, or "top out" then you probably haven't got enough rebound, if on the other hand they extend slowly with an audible "hiss" then the chances are it's to much. To much compression damping is easy to spot, every time you ride it your fillings will come lose and the front will skip everywhere.....

[chakraist]

I've got my rebound up a bit higher than standard because I was having problems with the wheelbase extending in the middle of the corner, even when trailing the brake slightly. Might just be my throttle control I need to work on but now I have the confidence to get on the gas a bit sooner.

[zadar]

I've got my rebound up a bit higher than standard
2 turns out is not higher,it is less rebound than normal on stock forks.
stock forks don't have enough rebound to begin with.

[yorkie_chris]

2 turns out is not higher,it is less rebound than normal on stock forks.
stock forks don't have enough rebound to begin with.

I found the rebound to be the worst thing about stock forks, the fact that they would shoot up so quick when coming off the brakes, even with heavier oil.

I started with the stock gsxr settings and have ended up on slightly less compression damping, slightly harder rebound, and quite a bit more preload iirc.

(And I noticed a massive difference between brands of oil in the srad600 forks.)

[chakraist]

2 turns out is not higher,it is less rebound than normal on stock forks.
stock forks don't have enough rebound to begin with.

I'm not really down with the know-how on the terminology but I've set it up so the forks come up slower.

[zadar]

I'm not really down with the know-how on the terminology but I've set it up so the forks come up slower.
that would be more damping.

[chakraist]

Just to resurrect this- my suspension adjuster on the bottom right hand side (compression on the right fork leg) seems to have become stuck- now can I just remove this with the nut and reset, or WD40 and work free? Little bit stumped :(

Thanks in advance.

[Bibio]

just a couple of thing to note:

the 'H' and 'S' markings on the adjusters does not mean Hard and Soft.

'H' is Slow and 'S' is Fast.

to explain this think of a spring between your hands (bulldog exercising thing) now compress the spring then slowly release it, this would be the 'H' setting. now compress it again and let it go, this would be the 'S' setting.

'H' (Slow) and 'S' (Fast) is the rate at which the dampening controls the spring in/on the fork/shoky. so the further you turn the setting to the 'H' the slower the dampening/rebound takes to return to 'rest' and the further you turn setting to 'S' the faster the dampening/rebound returns to 'rest'.

rebound: if the rebound has to much 'S' the front or rear of the bike will 'rise' when hitting a pothole, if the rebound has to much 'H' the front or rear will dive into a pothole

compression: if the compression has to much 'S' the front/rear will dive over bumps, if the compression has to much 'H' the front/rear will rise over bumps.

a good way of testing suspension is to ride over raised countdown strips at the end of DC's/MW's usually when coming to a roundabout. if you have it right then the bike should stay pretty level letting the suspension do the work.

spring rate: is the most important part. to hard a spring for bike/rider and no amount of compression/rebound adjustment will help, same goes for to soft a spring. dampening is the control of the spring, if the spring is wrong the dampening will be wrong.