sv650 fork TLS/R setting

[-Trollspeed-]

Hi,

I have built an Sv650 (from 2001) track bike. And I have a question for the track riders/racers.
My suspension set up is Ohlins rear shock and TLS/TlR front suspension (came with the bike) with gsxr wheel.
At first tests the front end was very nervous, it felt too hard. This became better after gradually setting the rebound damping fully in (slow out) and compression fully out (softest), (statig sag is good).
But the issue stays more or less the same: In turns with not very good surface, the front tends to 'tuck' away and gives verry little confidence, on good suface and long sweeping turns the feeling is better (but still not how I would like it)

I searched the forum but the only thing I found about the TL forks is that they are not very suited for an sv. Do you guys know why?
Gsxr 750 forks are often used, does anyone know the diffrence between the gsxr and TL forks?
Or maybe a softer spring will help? (the forks are for a much heavier bike, so comp. is fully out and rebound in...)

Any advice would be very welcome.

[yorkie_chris]

TL fork is 25mm internals, GSXR is 20mm. Some say one is better, both can work.

Sounds like your forks are valved way weak in rebound. What springs are in them and what do you weigh? What have you got shock length at?

P.S I have some 750-SRAD showa forks for sale ;-)

[jambo]

The first thing to remember about fitting forks from another bike is that they weren't designed and setup for your bike. Ideally you'd be after a fork of the same length, the same travel, same spring rate, and similar damping characteristics to the OE fork.

In practice you'll never quite get this, most GSXR forks are significantly shorter than the SV forks. TL forks are designed for heavier bikes, with different geometry.

Very few people will probably have tried both these, and standard forks to be able to hand good information on. You can get forks re-valved by companies like Maxton and Ktech who would be able to look at these forks on your bike and make changes to suit you. However if the forks are the wrong length for instance, they may not represent a great place to start.

Best of luck, and sorry if the above isn't terribly useful in giving a direct answer.

Jambo

[yorkie_chris]

The first thing to remember about fitting forks from another bike is that they weren't designed and setup for your bike. Ideally you'd be after a fork of the same length, the same travel, same spring rate, and similar damping characteristics to the OE fork.

Hang on what? The SV forks weren't designed or setup for the SV :smt043:smt043:smt043

GSXR forks are about an inch shorter than stock and they help matters along nicely. The SV has the geometry of a chopper as stock.

[jambo]

Hang on what? The SV forks weren't designed or setup for the SV :smt043:smt043:smt043

Having ridden plenty of bikes with simple damper rod forks (bandit 600, 1200, SV, VT500, Bros, etc) I would say the SV forks are no worse than any of the others. I'm pretty light, and even I prefer slightly stiffer forks springs in them, and I've generally preferred marginally thicker oil too. But they're genuinely not nearly as bad as some make out.

Jambo

[yorkie_chris]

But in this case you'd be taking supposedly finest steak (the ohlins in back), and then covering it in puke if you used stock forks.

You can't seriously be arguing that the stock door-closers are better suited to the SV than some cartridge forks? He's only having an issue because he's ragging the buggerance out of it on track!

[yorkie_chris]

Anyway off topic. What is your total sag? TLR forks have stiffer springs than TLS. Maybe too hard for you.

[jambo]

I'm seriously suggesting that just because a fork is made of good quality components, doesn't make it suited to every other bike.

I'm not looking to try and be awkward, but I feel people are overly critical of the standard bike, and the complexities of suspension setup can be ignored. The OP has clearly had the confidence to alter settings until he reached they best compromise he could with the setup he has. The obvious solution is to either replace the forks, or have them re-worked by a company that know what they're doing.

Jambo

[fastdruid]

I heard (but don't know how true it is) that the stock TL rebound adjuster has almost no taper so adjustment's are pretty much on or off.

btw wrt spring rates
TL-R are .934 Kg/mm
TL-S are .740 kg/mm
GSXR600K1-3 are .780 kg/mm
GSXR600K4-5 are .850 kg/mm
GSXR600K6-9 are .900 kg/mm
GSXR750Y-K3 are .780 kg/mm
GSXR750K4-5 are .780 kg/mm
GSXR750K6-7 are 1.000 kg/mm
GSXR1300X-K7 are .850 kg/mm
SV650SK1-7 are .706 kg/mm

So it looks like you either have too soft or too hard springs depending on which model you have and how much you weigh.

Currently I have GSXR1300X forks which I'm swapping to GSXR600K8, I probably get .85 springs as that's what is recommended for an SV for racing with my weight (and is what the current forks are).

Druid

[yorkie_chris]

I'm seriously suggesting that just because a fork is made of good quality components, doesn't make it suited to every other bike.

True. Ok lets try another angle, everything related to suspension is a compromise. Fitting forks from pretty much anything is less bad than the standard compromises.

Bear in mind if he was trying the same antics on stock forks he would probably spend the entire time rattling his way wide as they'd be on the bump stops the whole way into the corner.

Nothing is right as stock, here is pic of fork piston from GSXR 20mm showa I just pulled out of my bike.
http://img682.imageshack.us/img682/6708/dscf7568u.jpg
See the small notch in the sealing surface? That is just to make sure nobody dies if a retarded owner closes the compression bleed all the way.

Those forks work better as bog stock on SV than they do on SRAD IMO. We see how they do with all new valving and springs :-)

[zadar]

I'm seriously suggesting that just because a fork is made of good quality components, doesn't make it suited to every other bike.

I'm not looking to try and be awkward, but I feel people are overly critical of the standard bike, and the complexities of suspension setup can be ignored. The OP has clearly had the confidence to alter settings until he reached they best compromise he could with the setup he has. The obvious solution is to either replace the forks, or have them re-worked by a company that know what they're doing.

Jambo
No forks are suited for every bike and every rider. Your stock ones may work fine at normal speed for narrow group of riders, just like every other fork. Some do better job than others simply due to better design and quality.
OP altering settings is very small and narrow part of how forks work, it is just bleed hole. You can go up and down all day alone but it will not fix internal settings. Internals need to be set up for rider, bike and purpose. Once set up it does not matter what forks came from. TL forks have their own shortcomings that need to be fixed to work properly for your application.

[MHP ltd]

I can only quote you on how we set up the stock sv forks to work for the track.
I cant see the benefit of running shorter forks, it would drop a ton of weight onto the front tyre, upsetting the bias of the bike, and thus the increase in weight will make the steering heavy and want to wash out.

The std forks work very well once the damper rod has had the 4 x 10mm(?) welded up, then re-drilled with 1 small hole for compression damping.
A decent 20w fork oil, and some uprated springs (8.5 to 9.5 or anywhere between) and re-set the sag to 27mm using the preload spacer.

With compression and rebound, this will take them up to a decent race pace.

p.s. set forks flush to start with and lower only 3mm max at a time, 10mm max.

[zadar]

I cant see the benefit of running shorter forks, it would drop a ton of weight onto the front tyre, upsetting the bias of the bike, and thus the increase in weight will make the steering heavy and want to wash out.

That is whole point, to put weight on front and turn quicker.
Upset what bias? What is correct bias, stock?
If you lower front and reduce trail steering is lighter, not heavier. Less trail = less resistance to change direction.

[21QUEST]

I can only quote you on how we set up the stock sv forks to work for the track.
I cant see the benefit of running shorter forks, it would drop a ton of weight onto the front tyre, upsetting the bias of the bike, and thus the increase in weight will make the steering heavy and want to wash out.

The std forks work very well once the damper rod has had the 4 x 10mm(?) welded up, then re-drilled with 1 small hole for compression damping.
A decent 20w fork oil, and some uprated springs (8.5 to 9.5 or anywhere between) and re-set the sag to 27mm using the preload spacer.

With compression and rebound, this will take them up to a decent race pace.

p.s. set forks flush to start with and lower only 3mm max at a time, 10mm max.
I understand where MHP is coming from...

Personally, I've never felt the SV needs to be lowered 25mm and raised at the back another inch etc to make it work.

No doubt different riders would have preferences but I've never had a problem making the bike do what I needed, having only dropped it a few mm at the front. Peerhaps, I'm just too slow :p

Speaking to a well known Tuner(Steve Jordan) years ago, 10mm max(which is about max you could go anyway before things start getting intimate with each other) was his advice too.

I've run all manners of GSXR front end and have been happiest when I had either the SRAD 750(not so short) or using my stepped top yoke(added more more height).

Word of advice to the OP....Regards getting forks revalved, choose your Tuner very wisely if you decide to do that. That a company might be named J-Tech etc doesn't automatically mean, you'd be happy after spending good money. I've spent enough money on forks and know that is the case.

First thing you need to do is find out exactly what forks you have. measure the distance from bottom of head stock to centre of wheel spindle...when compared to stock , will tell you how much shorter forks are. Someone might have opened forks to change oil or the like and messed up with the oil weight /amount or not put them back properly. I always like to start with the simple things.


Cheers
Ben

[MHP ltd]

That is whole point, to put weight on front and turn quicker.
Upset what bias? What is correct bias, stock?
If you lower front and reduce trail steering is lighter, not heavier. Less trail = less resistance to change direction.

buy some scales and weigh you bike, it should 50 to 53% front bias.
once you exceed 55%( i recall:confused:) things will overload the front tyre, it's that basic.
I can understand you wishing to turn a tighter radius when cornering(understeer??) put weight on the front,
but
to turn quicker, more pressure/input into the handlebars.

[zadar]

I don't need scale to know what works for me :)
Ride height does not change static weight bias much at all, it changes how weight is transferred.

[-Trollspeed-]

Thanks for the response guys.

First thing I'll do when I come home is begin measuring: sag front and rear, frame to wheel spindle front and rear (with extended suspension), tube length front an shock length. I phoned the previous owner of the forks and shock, he recons the front was from a tl1000s, and didn't know the spring rate. The rear spring strength is 88 (Kg?) according to him, I'll try to check later.

Maybe another option: there are a set of gsxr 750 SRAD forks for sale nearby for 100 euro's; are these (with the right oil) original good for a decent trackday pace (or race pace)?
(maybe that comes out cheaper than revalving and new springs in mine..)

[Berlin]

Hi Trollspeed.
You say in your original post that you have the rebound set all the way in. Are you still running like that?

When fully in the bike should be virtually unridable and no wonder the bike wants to tuck in. :)

If the forks are working properly this should cause the forks to extend way too slowly to be useful. If they aren't you may well have something in the forks that shouldn't be there.

With the forks set up in the middle of their ranges the forks should be too much for the standard SV as the TL is a heavier bike. I'd imagine that you'd have to go the other way.

Could you give more details of where in the corner the bike is misbehaving? Entry, mid or coming out of the corner. Before you wind in the power or after? Before you release the brakes or after?

C

[yorkie_chris]

If the forks have never been apart then there might be loads of crap in the valves. My 600 ones were like this and it handled best with both bleeds fully closed. All the crap in there meant there was loads of free bleed bypassing the adjusters.

[fastdruid]

Given the age of the forks just an oil change may help, every s/h set of forks I've had apart have had some lumpy cats **** smelling[1] mess filling them.

Druid

[1] Why does old fork oil smell so bad?

[-Trollspeed-]

@ Berlin: yes, I'm running rebound 1 click out from fully in and comp. 1 click in from fully out. I tried a few minutes ago and when I turn rebound 7-8 clicks out, and compress the suspension the bike really bounces back on return, so probably something is wrong. The bike is stable under brakes and normal on entry, but when the bike really digs in to the corner and lean angle rises, it feels like the front is loosing grip/letting go. At first the rear was unstable under acceleration out of corners but after turning rebound and comp. of the rear shock two clicks harder it was better.


The previous owner of the forks phoned back this afternoon with more info. The forks were used on a race TLR and were revalved by Kayaba for that bike, so I'm afraid that means trouble (shimmed way to heavy, heavier bike-> less rebound damping needed?, and more comp. damping needed)

I've been measuring like you asked:

(I weigh 83Kg without gear)

Sag: Front 2,1 cm without rider 3 with me on it
Rear 1,6 cm without 4with me on it (too soft? but it is already wound up pretty hard)

The fork legs (top of legs to middle of spindle) are 71,6 cm
The outer leg tube is 49,5cm
From front wheel spindle to frame head (bottom yoke side) is 48,3 cm
The with between the legs is 21,5 (centre to centre)

Length of the rear shock is 35,8cm.

Is this in the region of your (track)bikes?
And from where to where do you measure rear ride height. (can vary a lot)

Thanks

[-Trollspeed-]

for pictures:

http://pbmagforum.co.uk/index.php?showtopic=5961&st=0

[fastdruid]

So TLR forks with Ohlins internals, 110 front might have something to do with the front feeling like it wants to tuck.

Druid

[-Trollspeed-]

yes, turns out (from the tlr owner) its revalved by Kayaba, probably Ohlins internals

last trackdays I've been using 120 front tyre (bt002) and 1cm higher at front to make it less nervous, but on not good surface corners, the problem stayed pretty much the same.

[21QUEST]

@ Berlin: yes, I'm running rebound 1 click out from fully in and comp. 1 click in from fully out. I tried a few minutes ago and when I turn rebound 7-8 clicks out, and compress the suspension the bike really bounces back on return, so probably something is wrong. The bike is stable under brakes and normal on entry, but when the bike really digs in to the corner and lean angle rises, it feels like the front is loosing grip/letting go. At first the rear was unstable under acceleration out of corners but after turning rebound and comp. of the rear shock two clicks harder it was better.


The previous owner of the forks phoned back this afternoon with more info. The forks were used on a race TLR and were revalved by Kayaba for that bike, so I'm afraid that means trouble (shimmed way to heavy, heavier bike-> less rebound damping needed?, and more comp. damping needed)

I've been measuring like you asked:

(I weigh 83Kg without gear)

Sag: Front 2,1 cm without rider 3 with me on it
Rear 1,6 cm without 4with me on it (too soft? but it is already wound up pretty hard)

The fork legs (top of legs to middle of spindle) are 71,6 cm...72cm
The outer leg tube is 49,5cm
From front wheel spindle to frame head (bottom yoke side) is 48,3 cm
The with between the legs is 21,5 (centre to centre) 21.4cm

Length of the rear shock is 35,8cm.

Is this in the region of your (track)bikes?
And from where to where do you measure rear ride height. (can vary a lot)

Thanks
Now, I'm no expert so only my opinion from my experience...

I've made some correction(in red) to some of your numbers. Fro memory but they are correct.

Springs appears to be in the ball park for your weight so we could take that out of the equation.

From those figures, forks are 2.5cm to 3cm(can't remember the length of the SV forks) shorter than SV forks

Rear Shock(what shock have you got on it again?) is 21mm longer than length of standard SV shock.

As said, if I were you, I'd be looking to get as close as to standard figures and then work from there. I know a lot of folks might say otherwise but 'simples' tends to work for me. Even racers would prefer different set ups.

I've never really liked the feel of the 120/70 myself but with the setup you have now, you don't have much choice anyway. That said, for track days etc, 120/70 wouldn't give the same odd feel as it gives(my opinion) on the road. I found the 120/60 gave a more neutral feel, which I prefer.

Anyhoo, to not digress too much., If the shock is after market and you can lower ride height at back a bit, I'd start from there. Possibly not so good for ground clearance(?) but you just have to bear taht in mind. I'd start with standard length and then go in 5mm 10mm increments.(you can then go 3mm up or down, depending on feedback you get.

Re forks, I know , they have been revalved but I still wouldn't jump straight into speding money on a errr re-revalve lol. If you are having to crank rebound up, you could try a thicker oil than what you have now....be good to know exactly(brand and weight) of ol you have in there. Saves you having to find your own base point.

Thicker oil should give you a bit more rebound before you run out.

Some of the terminology might be slightly misplaced but the core of the reasoning is good....again IMO

Try the simple sthings which shouldn't cost you much money. You might need to call in the experts in the end but you would have learnt something along the way anyways.

I have to repeat again lol, even if you have to call in the experts , choose wisely ....



Cheers
Ben

[yorkie_chris]

Only very slightly thicker oil though, they'll feel harsh as hell if you go for something far thicker.

Try table on here to find a suitable oil http://www.peterverdonedesigns.com/lowspeed.htm

[21QUEST]

yes, turns out (from the tlr owner) its revalved by Kayaba, probably Ohlins internals

last trackdays I've been using 120 front tyre (bt002) and 1cm higher at front to make it less nervous, but on not good surface corners, the problem stayed pretty much the same.

Re the bit I've highlighted, are the forks not flush with the top yoke?


Cheers
Ben

[zadar]

@ Berlin: yes, I'm running rebound 1 click out from fully in and comp. 1 click in from fully out. I tried a few minutes ago and when I turn rebound 7-8 clicks out, and compress the suspension the bike really bounces back on return, so probably something is wrong. The bike is stable under brakes and normal on entry, but when the bike really digs in to the corner and lean angle rises, it feels like the front is loosing grip/letting go. At first the rear was unstable under acceleration out of corners but after turning rebound and comp. of the rear shock two clicks harder it was better.


The previous owner of the forks phoned back this afternoon with more info. The forks were used on a race TLR and were revalved by Kayaba for that bike, so I'm afraid that means trouble (shimmed way to heavy, heavier bike-> less rebound damping needed?, and more comp. damping needed)

I've been measuring like you asked:

(I weigh 83Kg without gear)

Sag: Front 2,1 cm without rider 3 with me on it
Rear 1,6 cm without 4with me on it (too soft? but it is already wound up pretty hard)

The fork legs (top of legs to middle of spindle) are 71,6 cm
The outer leg tube is 49,5cm
From front wheel spindle to frame head (bottom yoke side) is 48,3 cm
The with between the legs is 21,5 (centre to centre)

Length of the rear shock is 35,8cm.

Is this in the region of your (track)bikes?
And from where to where do you measure rear ride height. (can vary a lot)

Thanks
This is curvy, right?
Sound like your oil is bad and/or high speed rebound is not right (shim stack).
When you measured sag on front did you calculate average for stiction? If not you need to. Good spring for your weight would be .90.
Shock is to long, don't go over 355mm, somewhere around 350-355 is good range. If your spring is wound up it is way to soft, you need around 115Nmm.

[fastdruid]

OK, some dimensions for you

Yoke fork Centres
TL1000S/R/hayabusa - 214mm
GSXR1000K1-8/GSXR600/750Y-K7 - 207mm

Yoke top fork dia
All - 50mm

Yoke bottom fork dia
TL1000S/R/hayabusa - 55mm
GSXR1000K1-6 - 54mm
GSXR1000K7-8 - 56mm
GSXR600/750Y-K5 - 54mm
GSXR600/750K6-K7 - 53mm

Yoke Offset
TL1000S/R/hayabusa - 32mm
GSXR1000K1-4 - 32mm
GSXR1000K5-6 - 30mm
GSXR1000K7-8 - 28mm
GSXR600/750Y-K3 - 32mm
GSXR600/750K4-5 - ??mm
GSXR600/750K6-K7 - 30mm

fork Length from Spindle centre to top of fork cap
TL1000S - 732mm
TL1000R - 717mm
Hayabusa - 725mm
GSXR1000K1-2 - 726mm
GSXR1000K3-8 - 720mm
GSXR600/750Y-K3 - 720mm
GSXR600/750K4-5 - ??mm
GSXR600/750K6-7 - 738mm

I have my hayabusa forks flush, your forks are ~8mm shorter.

Druid

[zadar]

GSXR600/750K4-5 - ??mm


722mm
Remember this measurements can be different for few mm depending on preload.

[fastdruid]

722mm
Remember this measurements can be different for few mm depending on preload.

Measurements blatantly stolen from this table
http://www.fastdruid.co.uk/albums/tmp/Fork-Conversion-Details.jpg

Although rotor thickness is wrong for TL1000R, they're 4.5mm (wear limit 4mm)

Druid

[zadar]

I know where it came from :), just saying fork length is within few mm.

[-Trollspeed-]

The rear shock is an Ohlins, maybe the previous owner still has a stiffer spring at home so I'll phone him tomorrow.

Ok, so looking at the figures it are TLR forks for sure. I'm making the special tool for disassembling the fork (pushing down the spring) today, so I can work on the forks this weekend.

I have no idea about what viscosity of oil is in the forks now, what do you think I'd use, 10W (motul, WP,..) maybe? And amount of air chamber, original TLR I suspect..

[zadar]

Depends what is in there, if you have ohlins valves they may be set up for thinner oil, 5W. Common oil used is 7W. Air chamber around 95mm.

[-Trollspeed-]

ok, I'll take a look when they are out and eventually take a picture if I don't see if it are ohlins or something else.

Thanks

[-Trollspeed-]

Time for an update:

To start: the fork oil was indeed very bad (and smelled that way). For the shims(/valves) I went to a local suspension expert, he checked them and adjusted the rebound shims a little bit, compression was ok. I changed the oil with 7,5w reassembled them. The forks are back in now (flush with the yoke), I have a slower rebound now with the adjuster half the way in then I had with fully in before the overhaul, I cant wait for the first trackday to test it.
I allso changed the radial 19mm brembo brake cylinder for a conventional (i think 15mm) nissin one to try. The brembo had a very hard lever, so stopping power was no problem, but feel was not very good.
Today I lowered the rear a bit (shock 16-17mm shorter), mounted a Pilot power 2ct(160) for the first test days, and changed the standard rear fairings for an used gsxr poly unit, I allso have the front ones but I'm not sure if I'll use it , I like the 'naked' look with usd forks too.


http://img502.imageshack.us/img502/1328/img4247k.jpg (http://img502.imageshack.us/i/img4247k.jpg/)

[-Trollspeed-]

http://img237.imageshack.us/img237/6016/img4248e.jpg (http://img237.imageshack.us/i/img4248e.jpg/)

[fastdruid]

Is that a pillion peg I can see on the LHS? ;)

Druid

[-Trollspeed-]

Is that a pillion peg I can see on the LHS? ;)

Druid



Indeed, it used to be a road bike too, and the girlfriend loves it so...




Anyone any good/bad expirience or advice with axial compared to radial master brake cylinders?

And do race fairings give a big diffrence in terms of protection in case of a crash? (I have a pair of used '01-'03 here)

[fastdruid]

Lol, I thought it was meant to be a track bike. ;)

Only trying a radial M/C for the first time now (and currently its sat in the kitchen!) so no idea, it does look like there may be a bit less clearance but that's not a problem if you don't have a fairing!

Interesting question, hard to say really, I've never dropped it with the GSX-R fairing on but I've dropped the NC35 and that IMO would have done more damage without the fairing. OTOH it made a mess of the fairing!

http://www.fastdruid.co.uk/albums/NC35no2/thumbs/640x480NC35Damage2.jpg

It can provide a bit of cushioning when it falls over, obviously makes a mess as it does it but a trashed fairing is better than a trashed frame.

Druid

[Berlin]

Glad to hear you seem to have it sorted. Have you tried Bouncing the suspension to see how it's behaving with the new Oil and adjustments? The forks should rebound and *just* go over into the *start* of a second bounce if set correctly. Set the rear Ohlins unit up at the standard settings recommended and then move no more than two clicks from there at the rear until you have the front sorted.

When the bike is pushed down via the seat, the front and rear should work together and the bike should rise and fall at the same rate back and front. you shouldn't get a "sea-saw" effect where the front goes down or comes up before or after the rear.

And I'd definitely be using a 120/70 front on there for the track.

Keep us informed as to how she behaves on the track! :)

C

[-Trollspeed-]

jes , it was a road/track bike, now only track.

In two weeks its going to the dyno again.

I'll try the fairing this weekend, I've just got an alu front fairing support with dash plate for a (I think Stack or Scitsu) rev counter, so I'm sourcing ebay for a good rev counter. If anyone has one for sale...Pm me...

[-Trollspeed-]

Glad to hear you seem to have it sorted. Have you tried Bouncing the suspension to see how it's behaving with the new Oil and adjustments? The forks should rebound and *just* go over into the *start* of a second bounce if set correctly. Set the rear Ohlins unit up at the standard settings recommended and then move no more than two clicks from there at the rear until you have the front sorted.

When the bike is pushed down via the seat, the front and rear should work together and the bike should rise and fall at the same rate back and front. you shouldn't get a "sea-saw" effect where the front goes down or comes up before or after the rear.

And I'd definitely be using a 120/70 front on there for the track.

Keep us informed as to how she behaves on the track! :)

C



yes, bouncing the front with new oil and shims sorted gives more rebound with rebound set on half, then it had when set on fully closed before. So it should be a good diffrence :)

Do you know where I can find the standard settings from Ohlins?
I'm going to try a bt002 120/70, and have Pilot power (rear) from my other bike, maybe I will switch to supercorsa's if they aren't sticky enough.