SV and Pirelli help

[JJ58]

Hey,
Does anyone run the Pirelli SC1/SC2 Supercorsa's on their Pro Twin bike?

For the national series in Canada the Pirelli is a spec tire.

In four races I've spent around NZ$1,500 with the suspension tec's at the track (Yes I know, you guys have it really good getting free advice of Mr Taylor) getting my bike to handle decent with Dunlops for our regional championship and am unfortunately struggling with the Pirelli's.

In switching I make the adjustments for ride height (circumfrence of tires X pi / 2 then the difference in hieght).

I heat the Pirelli's to 76C, set the pressures to 32psi F and 28psi R, then head out (as recommended by the Pirelli tec's).

Pressures coming in are around 33C F and 30.5 R and the temp via the pyrometer is around 41C f and 38C R in the centre of the tire (all good according to the Pirelli tec's)

Ambient temperature is around 27-31C.

The problem is a squishy feeling in the front that makes me nervous + ripping through tires. I've kind of combatted this via adding more pressure..... The rear end slides under aggresive power.

The suspension changes I've made to combat this is:
reduce oil level in front forks (emulated dampener rods at present) and increase pre load 2mm to raise the working part of the suspension out of the poor progression area.

With the rear I've reduced the compression and increased the pre-load (to soften and lift out of poor progression area).

All I'm wanting to know is:
Is there anyone who has had racing success with the super corsa's on a SV?
If so, what are the tire pressures and temp going out/in?
Do you know how you set up compares to the setting for Dunlop 209's?
What way do you adjust the pressure's for changes in temperature?
Anything else you've noted?

Cheers and thanks for your help in advance!!

[ajturbo]

think you best save ya money and go bucket racing...

[Tony.OK]

Hey,


I heat the Pirelli's to 76C, set the pressures to 32psi F and 28psi R, then head out (as recommended by the Pirelli tec's).
Pressures coming in are around 33C F and 30.5 R and the temp via the pyrometer is around 41C f and 38C R in the centre of the tire (all good according to the Pirelli tec's)



Shouldn't your pressure should be set on a cold tyre not a heated one,thats why your not getting much of a change in pressure when ya come back in,my understanding is there should be around a 4-6 psi increase.
Which in turn will let your tyres shear from being underinflated.
I inadvertedly ran 26psi cold in my front for a day and it started to tear,then next day ran 31 cold and it revived the tyre really well.
Different bike I know but same tyres:mellow:

[GSVR]

Somethings definately not right if your chewing out fronts. SC0 fronts seem to last for ages normally. Our current F3 national champ (codgyoldracer) runs Pirelli's on his SV650 but I think its widely accepted that Dunlop N-Tecs are the go at the moment.

I had this problem once and went through 2 front tyres at one meeting. This was with a GSXR front end in the SV. I first thought I was causing it by trailing the front brake deep into the corner but latter found it was one of the dampening rods was coming apart.

I would lift the front of the bike remove the front wheel and fork springs and emulators then move the forks by hand to see if they are both the same without any sticking etc. Then set the emulators and make sure they are in the right way (relieve spring to the top). Check the oil levels by sliding the fork legs all the way up without springs in and measuring.

Not to sure were should be going with front tyre pressure but 30psi cold is a good starting point.

Sorry if the above sounds a bit simplistic but its just what I would try as well as going back to baseline settings on the rear shock.

[JJ58]

Cheers GSVR, always good to check the obvious.

forks are in tack, emulators seated correctly and correct oil level (measured with springs in).

Pirelli International always recommends setting tyre pressures warm @ 76C.... Only Dunlops are to be set cold.

Suspension is in functional working order. The info I'm after is really any info on spring rate/valving changes between using each tire....Also nitrogen is used as recommended by Pirelli, therefore fading not really an issue.

Cheers

[FROSTY]

I Ran the SC0 on the front of my SV for 2 full seasons with no issues with the front tyre. I would strongly suggest you might want to do your tyre pressures cold and at 32psi as a starting point.
I did find they "announced" when they were close to their limits pretty well.

[Robert Taylor]

Hey,
Does anyone run the Pirelli SC1/SC2 Supercorsa's on their Pro Twin bike?

For the national series in Canada the Pirelli is a spec tire.

In four races I've spent around NZ$1,500 with the suspension tec's at the track (Yes I know, you guys have it really good getting free advice of Mr Taylor) getting my bike to handle decent with Dunlops for our regional championship and am unfortunately struggling with the Pirelli's.

In switching I make the adjustments for ride height (circumfrence of tires X pi / 2 then the difference in hieght).

I heat the Pirelli's to 76C, set the pressures to 32psi F and 28psi R, then head out (as recommended by the Pirelli tec's).

Pressures coming in are around 33C F and 30.5 R and the temp via the pyrometer is around 41C f and 38C R in the centre of the tire (all good according to the Pirelli tec's)

Ambient temperature is around 27-31C.

The problem is a squishy feeling in the front that makes me nervous + ripping through tires. I've kind of combatted this via adding more pressure..... The rear end slides under aggresive power.

The suspension changes I've made to combat this is:
reduce oil level in front forks (emulated dampener rods at present) and increase pre load 2mm to raise the working part of the suspension out of the poor progression area.

With the rear I've reduced the compression and increased the pre-load (to soften and lift out of poor progression area).

All I'm wanting to know is:
Is there anyone who has had racing success with the super corsa's on a SV?
If so, what are the tire pressures and temp going out/in?
Do you know how you set up compares to the setting for Dunlop 209's?
What way do you adjust the pressure's for changes in temperature?
Anything else you've noted?

Cheers and thanks for your help in advance!!

Questions and suggestions relevant to your problems;

1) Are the damper rods original and modified or are they Traxxion rods? ( These are very good and I have just ordered some more off Traxxion for the NZ market ) If they are oem and have been modified in the Race Tech suggested method you actually get a dead area of high speed rebound damping.
2) Are the 64 lb/in poppet springs fitted and how many turns of preload?
3) Oil level with emulators in and springs removed, forks in full closed position?
4) Oil viscosity ( preferably centistroke rating at 40 degrees celsius ) and brand?
5) Spring rate and static sag?
6) Your weight and height?
7) What spring rate is fitted into the Penske rear shock?
8) What length are you running the shock at?
9) Is it the standard piston in that shock, a Penske digressive or a Traxxion progressive? Or is it a piston that provides a steep slope to the damping curve to ''catch'' long stroke movements? If the rear end is sliding too readily ( and the spring rate is okay ) then the internal valving and bleed bypass is too aggressive and no amount of external clicker fiddling will correct it. I am not there on the spot but I am guessing that the front and rear are perhaps also not balanced in action, the rear is underworking and thereby overworking the front................but I may be wrong.
The carcass construction between Pirelli and Dunlop is different and it will load the suspension differently. I am sure that following your answers we can provide some plausible suggestions.

[JJ58]

Wow Tony, 32psi cold is high and miles away from the manufacturers recommendation. I might try it, but I bet you struggle for grip in the rear on corner exit. I tried 32psi warm in the rear and it was like I was dirt tracking. The top super bike guys run about 26psi warm on these rear tires to get the grip coming out of the corner. Pirelli advise to not take the rear above 31psi warm.

The bike did chew tires up for a bit, but I fixed that by making the suspension changes above, as the SV's have a poor progression linkage/dampning.

The issue with tire wear is that the Pirelli's are far softer than the Dunlop's so naturally I'll be wearing them out sooner. The Dunlop's are triple compound and have a stiffer carcase. Hence the 30 laps to a tire compared to the 200+ laps on the Dunlops at speed.

So it looks like no-one has had a good tire testing session to work out the differences? I'm getting pretty close and it's costing a lot (thank goodness we get prize money here). I'll post up what I find out.

Cheers

[JJ58]

Cheers Robert.
I'm away from my notes at the mment, but will get back to you in the next few days with the info.

Just for clarification the "not balanced in action" means that mid corner there is not correct weight allocation the the front and back of the bike?

[JJ58]

Hey Frosty....Just for your info:
http://www.orionmotorsports.ca/prod_nitrogen.htm

Check out the tire pressures.

[FROSTY]

Hey Frosty....Just for your info:
http://www.orionmotorsports.ca/prod_nitrogen.htm

Check out the tire pressures.
I think that may be the difference--we just run air mostly

[cowpoos]

Shouldn't your pressure should be set on a cold tyre not a heated one,thats why your not getting much of a change in pressure when ya come back in,my understanding is there should be around a 4-6 psi increase.
Which in turn will let your tyres shear from being underinflated.
I inadvertedly ran 26psi cold in my front for a day and it started to tear,then next day ran 31 cold and it revived the tyre really well.
Different bike I know but same tyres:mellow:
pressure is best set hot...at track running temp...

[Robert Taylor]

Cheers Robert.
I'm away from my notes at the mment, but will get back to you in the next few days with the info.

Just for clarification the "not balanced in action" means that mid corner there is not correct weight allocation the the front and back of the bike?

That is a good part of it yes, its also about controlled weight transfer.
And yes as per your previous post the rear linkage on that bike is more than a little wanting, it was built as a commuter bike and not as a race bike.
This is one of the models we always have a little difficulty setting up, although I havent mapped it I suspect that the motion ratio that the linkage imparts to the shock is very lazy i.e it only moves the shaft slowly, at least in the first part of travel. That means the damping build up is slow and a relatively aggressive damping spec ( internally ) has to be arranged. The problem being is that if you are so reliant on damping to hold it in its stroke the setting window becomes much narrower between what works and what doesnt. In all fairness that basic problem is irrespective of what shock is fitted into the rear, although some shock designs are more fundamentally accomodating of the issue. I also suspect that raising ride height ( by shock length ) may in fact swing the linkage into a dead zone of movement.
Before anyone else may suggest it why not just fit firmer springing? The answer is that yes it will ''fudge it'' a bit BUT the spring force will ramp up much more at longer stroke movements giving a very harsh ride. And it will step out too readily finishing the turns under power. Its always a fine balance between springing and damping. Oversimplistically ( and I keep repeating this everywhere ) springing is about position and damping is about rate of change of position.
Heck I may get some data off Ohlins re this as it has for too long been a niggling question in the back of my mind.
And another question, does the bike have any inkling of a tendency to ''stand up'' mid corner?

[cowpoos]

I think that may be the difference--we just run air mostly
I think you have been more likely misinformed frosty...

[cowpoos]

.
Before anyone else may suggest it why not just fit firmer springing? The answer is that yes it will ''fudge it'' a bit BUT the spring force will ramp up much more at longer stroke movements giving a very harsh ride.

Okay I was thinking that just the second yo wrote that last piece...hmmm...what about running a higher spring rate with shortening the lenght [eye to eye] of the shock..and running slightly less sag? or would that still be in the sense of 'FUDGING IT' ???

[Robert Taylor]

Okay I was thinking that just the second yo wrote that last piece...hmmm...what about running a higher spring rate with shortening the lenght [eye to eye] of the shock..and running slightly less sag? or would that still be in the sense of 'FUDGING IT' ???

No that wouldnt neccessarily work so well as youd be compromising the geometry setup, the SV genearlly likes to run tall when raced.

[JJ58]

Robert, I think you've hit the nail on the head!! I thought they were two seperate issues, but maybe they're one...that is the issue in changing tires and the rear issue that I'm having with the SV under hard acceleration.

....I've worked out that the progression isn't great in the rear.... Putting two and two together I think that the Pirelli's causing the rear to use a different part of the progressional stroke in the turn to the Dunlop....

...It was going to be my project to play with the rear ride hieght over the next two races to try and combat this issue, and also to try a get the best anti-aquat angle for the SV..... I've had the rear shock internally revalved numerously and have tried different spring rates front and rear to combat this issue......So you've saved me plenty of time telling me about the chances of getting into the dead progression area.......

I'll be looking forward to what you hear from Ohlins on this matter.

Just out of curiousity, would changing the "dog bones" in the rear linkage alter the progression? I think we may be able to do that under our rules.

[DEATH_INC.]

Yes, in theory if ya lower the shock back to the original height, then alter the ride height with the dogbones it'll keep the link in the same position and part of the progressive curve as stock...BUT the shorter dogbones will normally make the progressive curve a little more aggressive than stock....prolly worth a try though if ya can do it...and of course then you can bugger around with various combos of dogbone and shock length :rolleyes:

[FROSTY]

Over the last year its occurred to me that with our current F3 rules why arent we going back to a clean slate with our SV setups?
Im well aware I'm oversimplifying but why not simply measure up all the numbers from a (for example) K3 gsxr600 and build a front and rear suspension setup the same?

[Robert Taylor]

Robert, I think you've hit the nail on the head!! I thought they were two seperate issues, but maybe they're one...that is the issue in changing tires and the rear issue that I'm having with the SV under hard acceleration.

....I've worked out that the progression isn't great in the rear.... Putting two and two together I think that the Pirelli's causing the rear to use a different part of the progressional stroke in the turn to the Dunlop....

...It was going to be my project to play with the rear ride hieght over the next two races to try and combat this issue, and also to try a get the best anti-aquat angle for the SV..... I've had the rear shock internally revalved numerously and have tried different spring rates front and rear to combat this issue......So you've saved me plenty of time telling me about the chances of getting into the dead progression area.......

I'll be looking forward to what you hear from Ohlins on this matter.

Just out of curiousity, would changing the "dog bones" in the rear linkage alter the progression? I think we may be able to do that under our rules.

Yes, Death and Frosty also make some sense re this. I will make it my mission to speak to Ohlins this week re SV650 and GSXR600 linkage curves. If I can access a couple of bikes I may also do this myself, but that will take rather longer.

[JJ58]

Yeah, interesting...
....I'm keen on trying it out and giving some feedback. I'm pretty sensitive to changes on the bike so I'm sure we'll be able to get some good set up notes.

Yeah, Robert it'll be great if you could get some data on this from Ohlins and instruct on possible changes and I'll hunt out where I can get some shorter dogbones from..... I'll be away racing from Thursday and won't be back until 2nd week in July. I then have a race a week later that I get three free practice days for. This would be the perfect opportunity for testing this..... I know where there's an old k3 sitting so I might try and take some measurements too.

Cheers

[Robert Taylor]

Yeah, interesting...
....I'm keen on trying it out and giving some feedback. I'm pretty sensitive to changes on the bike so I'm sure we'll be able to get some good set up notes.

Yeah, Robert it'll be great if you could get some data on this from Ohlins and instruct on possible changes and I'll hunt out where I can get some shorter dogbones from..... I'll be away racing from Thursday and won't be back until 2nd week in July. I then have a race a week later that I get three free practice days for. This would be the perfect opportunity for testing this..... I know where there's an old k3 sitting so I might try and take some measurements too.

Cheers

I have requested this info so we have to await a reply, it seems that half of Scandinavia is on holiday at present enjoying the one week of summer that they get. Thinking about it there are 2 or 3 likely scenarios;

1) The ''start ratio'' of the link is weak and it blows through its stroke too readily and arrives at the progressive part of the link which may be aggressive. The shock shaft speed accelerates dramatically and so does the damping, this screws tyres.
2) The start ratio is weak and there is little progression in the link also. So it continues to blow through it stroke compressing the spring more and more and accumulating spring force. This scenario would cause understeer off the turns.
3) ( least likely ) The start ratio is strong and the progression is weak.

It will be interesting to know what type of piston design is in that Penske shock? Some of their tuners favour a very agressive low speed damping build up followed by a flat slope. The problem is when you get a damp race with poor grip there is rather less grip with this mentality, and you cannot successfully tune it out externally with clickers. With our own favoured Viking shocks we are having good success with a moderate/ sensible amount of low speed damping followed by a steeper slope to ''catch'' sudden movements. This approach can very often be your friend on bumpy tracks.

As far as different length dogbones are concerned the jury is out on that one, they worked okay for us on earlier model R1s but bear in mind that there are plenty of companies making them as its something to sell and make money out of rather than if it neccessarily works. With all respect to the protectors of the ''free'' world they can get rather economical with the truth when it comes to the hype of marketing products. Having said all that if anyone has had conclusive / very accurately assessed success with varied dogbone lengths on fuel injected SV650s Id love to hear.

Anyway, we shall see what bounces back in due course......

[Robert Taylor]

The start ratio is weak imparting a very slow velocity to the shock ( any shock ) meaning weak damping build up. So the shock has to have quick low speed initial damping build up both internally through the shaft jet and into the reservoir, before there is any hint of lifting the valving stack. The opening point of the valving stack has to also be reasonably firm with a decent slope in the curve to catch sudden movements on bumpy tracks.
The link is designed for compliant road use as the Suzuki factory never had any intention that such a bike would be used for racing.

[JD Racing]

Do you have a choice of compound for the front?
You may be better off with an SC2 front, when switching from Dunlops to Pirelli a lot of riders struggle with the difference in feel. The Dunlop has a stiff sidewall with a triangular profile, the Pirelli is a rounder profile with a softer sidewall hence the wallowy feel, what you are saying about the feel is very common, some riders just can't get their heads round it at all. Although they are the same construction you will most likely find that the SC2 gives more support.

Oil viscosity and ambient air temperature are important tuning factors with SV forks, forks that are stiff in a Canadian spring will be soft and wallowy in summer, choose your oil by it's Centistoke rating not the SAE value.

You shouldn't need to mess about with dog bones a good tuner should be able to sort the shock out, unfortunately it doesn't look like you've found a good tuner. Which Penske shock is it?

[Robert Taylor]

Do you have a choice of compound for the front?
You may be better off with an SC2 front, when switching from Dunlops to Pirelli a lot of riders struggle with the difference in feel. The Dunlop has a stiff sidewall with a triangular profile, the Pirelli is a rounder profile with a softer sidewall hence the wallowy feel, what you are saying about the feel is very common, some riders just can't get their heads round it at all. Although they are the same construction you will most likely find that the SC2 gives more support.

Oil viscosity and ambient air temperature are important tuning factors with SV forks, forks that are stiff in a Canadian spring will be soft and wallowy in summer, choose your oil by it's Centistoke rating not the SAE value.

You shouldn't need to mess about with dog bones a good tuner should be able to sort the shock out, unfortunately it doesn't look like you've found a good tuner. Which Penske shock is it?

I concur exactly, the linkage is what youve got so the tuner should be able to make the shock work. I think there is too much credence paid to ''full external adjustability'' which of course doesnt actually alter the basic character of the shock. You very often have to make internal changes to make it work in harmony with the motion ratio and leverage imparted to it. Just this last weekend I evidenced one of these purported US made ''fully adjustable'' shocks that was rapidly burning up tyres. It clearly needed some work.
I think also that there is a mindset that softer compounds always afford more grip, that is not neccessarily so. Cold track temperatures for very complex reasons often require harder compounds and more spring force / damping force to ''push'' the tyre harder onto the track. Thats an oversimplistic explanation but the reality can often be that.
SV and indeed all damper rod forks are VERY ambient temperature sensitive and I have posted before about this and the need to request both the centistroke ratings and to select a higher quality rather than cheap oils.

[Dom]

Hey John. About the tires. They are totally different to what are avaliable in New Zealand. In New Zealand, most guys run 0, 1 and 2. Where as in the states I was running 1, 2, 3 and 4 and things in between. In the US, I actually preferred the 2 front over the 1 as it has a totally different carcass built into it and felt way firmer. Also, we ran 1 on the rear sometimes and they grip so much better. We could get them to last a 28 lap Superbike race on the right day, right track so maybe thats something else you could try down the track when Robert gets ya soughted with ya bike. Everyone likes grip.

[Shaun]

Hey John. About the tires. They are totally different to what are avaliable in New Zealand. In New Zealand, most guys run 0, 1 and 2. Where as in the states I was running 1, 2, 3 and 4 and things in between. In the US, I actually preferred the 2 front over the 1 as it has a totally different carcass built into it and felt way firmer. Also, we ran 1 on the rear sometimes and they grip so much better. We could get them to last a 28 lap Superbike race on the right day, right track so maybe thats something else you could try down the track when Robert gets ya soughted with ya bike. Everyone likes grip.



Good on ya for sharing your testing thoughts mate