the bb trackday thread.

[Birky_41]

Fleegle said:

Was it your mate who came off at the end of Corams where you turn left on the start finish straight?

Yep thats him, honestly its the worst Ive seen, we were passing a group of riders and he was committed. Said he went for the brake and it just came right back so he stood up then leaned hard left even though he was heading for the grass (approx 20 ft left of where the actual left was). He hit that ground hard...it spat him into the track and then bounced him again onto the grass. Bikes dented a fair bit but fixable but he is very sore

Turns out the front brake seal has perished so would feel fine in the pits but 3-4 laps in would go right back to the bar. Wasn't fade as he runs a good setup. Started doing it the session before but he thought it was getting hot...obviously not

[Fleegle]

I thought it was a bad one as they put the medical car on the circuit before everyone was off. Hope he heals quick

[Fleegle]

Birky_41 said:

Got some tyre issues so whether I want to or not I need to spend some money on getting the forks setup properly before cadwell on the 10th and need to change this front tyre! 2 track days and its dead





Right looking at it from behind

Sort your suspension out. It'll be cheaper that destroying tyres in the long run. We all commented on how the track had been kind to our tyres. I ended up with lovely even wear, no tears at all.

[Birky_41]

Fleegle said:

Sort your suspension out. It'll be cheaper that destroying tyres in the long run. We all commented on how the track had been kind to our tyres. I ended up with lovely even wear, no tears at all.

On the phone to MCT today to do exactly that. My road bike (An MV Dragster RR) has the same issue, it must be my riding style so Im going to sort both together

My rear is really good though

[snorky782]

Birky_41 said:

Yep thats him, honestly its the worst Ive seen, we were passing a group of riders and he was committed. Said he went for the brake and it just came right back so he stood up then leaned hard left even though he was heading for the grass (approx 20 ft left of where the actual left was). He hit that ground hard...it spat him into the track and then bounced him again onto the grass. Bikes dented a fair bit but fixable but he is very sore

Turns out the front brake seal has perished so would feel fine in the pits but 3-4 laps in would go right back to the bar. Wasn't fade as he runs a good setup. Started doing it the session before but he thought it was getting hot...obviously not

The end of Corams in the fiddly corners doesn't seem like the best place for two of you to be overtaking a group of other riders on a trackday. One rider overtaking another rider maybe, but two of you overtaking a few of them seems like asking for trouble.

[Birky_41]

snorky782 said:

The end of Corams in the fiddly corners doesn't seem like the best place for two of you to be overtaking a group of other riders on a trackday. One rider overtaking another rider maybe, but two of you overtaking a few of them seems like asking for trouble.

He was in front on the left, two riders were slightly ahead of him on the right I was behind all that lot

We have pretty good track etiquette thanks as I wouldnt want someone doing it to me

[fergus]

Birky_41 said:

On the phone to MCT today to do exactly that. My road bike (An MV Dragster RR) has the same issue, it must be my riding style so Im going to sort both together

My rear is really good though

don't think you can improve that much?

[snorky782]

Birky_41 said:

He was in front on the left, two riders were slightly ahead of him on the right I was behind all that lot

We have pretty good track etiquette thanks as I wouldnt want someone doing it to me

I'm not having a pop, just saying that sometimes patience is a virtue. There are no cups for whatever times you do on a track-day and overtaking two people on the brakes (especially ones that are known to go back to the bar)out of Corams and into that left is a pretty harsh move by anyone's standards.

[Birky_41]

fergus said:

don't think you can improve that much?

Yep Im really pleased with the rear wear, especially given the heat. Lacks a bit of grip being an endurance compound but just know its capabilities

Suspension is spot on though

[moto_traxport]

Fleegle said:

Birky_41 said:

Got some tyre issues so whether I want to or not I need to spend some money on getting the forks setup properly before cadwell on the 10th and need to change this front tyre! 2 track days and its dead





Right looking at it from behind

Sort your suspension out. It'll be cheaper that destroying tyres in the long run. We all commented on how the track had been kind to our tyres. I ended up with lovely even wear, no tears at all.

That inch and half tear on the outer edge of the front can sometimes be geometry. I got it on my bike when I ran increased offset yokes (i.e. slow steering). It can also happen by too little preload on the shock, or the shock too short (i.e. robbed out of another type of GSXR - basically anything that causes it to turn slow and scrub itself 'round the corner. It might not be, could be other stuff, just a thought ...

Wear on the rear looks spot on.

[Biker's Nemesis]

snorky782 said:

I'm not having a pop,

Yes you are.

[Biker's Nemesis]

moto_traxport said:

- basically anything that causes it to turn slow and scrub itself 'round the corner. It might not be, could be other stuff, just a thought ...

Beer belly?

[moto_traxport]

Biker's Nemesis said:

moto_traxport said:

- basically anything that causes it to turn slow and scrub itself 'round the corner. It might not be, could be other stuff, just a thought ...

Beer belly?

Mainly on gin now due to advancing years!

Those bloody 02-03 R1 triple clamps I had in it for 2 or 3 years did nothing for me except create the same wear pattern Birky is on about and spit bits of the front tyre up the bellypan. They need using in conjunction with a longer shock apparently, or just put the original fast steering ones back in.




Edit - I've f'kin had it with photos on the internet! Photobucket has finally done me in by trying to get me to download stupid Apps for games with cartoon (feathered) birds and the above is my best effort with thumbsnap.

Edited by moto_traxport on Monday 25th July 20:25

[moanthebairns]

Anyone at croft 11th and 12th next month.

[Birky_41]

moto_traxport said:

That inch and half tear on the outer edge of the front can sometimes be geometry. I got it on my bike when I ran increased offset yokes (i.e. slow steering). It can also happen by too little preload on the shock, or the shock too short (i.e. robbed out of another type of GSXR - basically anything that causes it to turn slow and scrub itself 'round the corner. It might not be, could be other stuff, just a thought ...

Wear on the rear looks spot on.

I think you are spot on here. Its geometry definitely I think. Its a Y/K1 750 with a K4 750 fork and K5 1000 rear shock. Strangely though it never did this with the Pirelli SC1

Either ways I know there is an issue. I have the Comp and Rebound on max hard and pre load set 1 1/2 turns from max in to try and firm it up but its just masking a problem. MCT cant get me in until October so I have emailed FTR and tyres4bikes who can sort my forks and supply another tyre at a decent price. Will see what they both say, got 2 weeks to sort it

[Birky_41]

moto_traxport said:

That inch and half tear on the outer edge of the front can sometimes be geometry. I got it on my bike when I ran increased offset yokes (i.e. slow steering). It can also happen by too little preload on the shock, or the shock too short (i.e. robbed out of another type of GSXR - basically anything that causes it to turn slow and scrub itself 'round the corner. It might not be, could be other stuff, just a thought ...

Wear on the rear looks spot on.

I think you are spot on here. Its geometry definitely I think. Its a Y/K1 750 with a K4 750 fork and K5 1000 rear shock. Strangely though it never did this with the Pirelli SC1

Either ways I know there is an issue. I have the Comp and Rebound on max hard and pre load set 1 1/2 turns from max in to try and firm it up but its just masking a problem. MCT cant get me in until October so I have emailed FTR and tyres4bikes who can sort my forks and supply another tyre at a decent price. Will see what they both say, got 2 weeks to sort it

[upsidedownmark]

Disclaimer: Not a suspension expert (but mechanically minded, interested, and know a bit on the theory side) Others here know a lot more..

Picking up on earlier comments about 'anything that makes it turn slower' sets off alarm bells - unless you've dropped the yokes down the forks, winding on preload will have increased the front ride height, and will make it steer slower. It also doesn't really stiffen anything.. (unless you have a progressive spring)

i.e. If the spring is 10kg/cm, it will move 1cm for 10kg, no matter where in the stroke. preload will move where it starts - so if you have 10kg of preload, then load the fork by 10kg, the fork won't quite move - 20kg and it will move 1cm etc. Assuming the bike is heavy enough to move it off the top stop, all preload is really doing is adding ride height; Provided you don't get coil bound, preload will mean the front is higher for any given load, but it won't make it stiffer.

Damping also has zero effect on where you end up (steady state), but a lot of effect on how / how fast it gets there (transients), basically damping controls the rate of motion only. So it'll dive more slowly when you hit the brakes, but finish up just as compressed. I'd be worried about having a lot of rebound (in particular) dialled in, really you want as little as possible, potentially that's jacking its self down over anything bumpy - it doesn't get a chance to come back up before the next bump hammers it down again. Generally less clear on setting bump rates..

[MotorsportTom]

Anglesey on Friday and then A morning at Mondello Park on Sunday.

Anybody heading to either?

[fergus]

upsidedownmark said:

Disclaimer: Not a suspension expert (but mechanically minded, interested, and know a bit on the theory side) Others here know a lot more..

Picking up on earlier comments about 'anything that makes it turn slower' sets off alarm bells - unless you've dropped the yokes down the forks, winding on preload will have increased the front ride height, and will make it steer slower. It also doesn't really stiffen anything.. (unless you have a progressive spring)

i.e. If the spring is 10kg/cm, it will move 1cm for 10kg, no matter where in the stroke. preload will move where it starts - so if you have 10kg of preload, then load the fork by 10kg, the fork won't quite move - 20kg and it will move 1cm etc. Assuming the bike is heavy enough to move it off the top stop, all preload is really doing is adding ride height; Provided you don't get coil bound, preload will mean the front is higher for any given load, but it won't make it stiffer.

Damping also has zero effect on where you end up (steady state), but a lot of effect on how / how fast it gets there (transients), basically damping controls the rate of motion only. So it'll dive more slowly when you hit the brakes, but finish up just as compressed. I'd be worried about having a lot of rebound (in particular) dialled in, really you want as little as possible, potentially that's jacking its self down over anything bumpy - it doesn't get a chance to come back up before the next bump hammers it down again. Generally less clear on setting bump rates..

+1. Check front rebound. As the front packs down on the turn into a corner, the effective rake is steepened, which will push more weight onto the front, stressing the front tyre more. See what happens if you take off some of the slow speed rebound on the front?

[Steve Bass]

Birky_41 said:

moto_traxport said:

That inch and half tear on the outer edge of the front can sometimes be geometry. I got it on my bike when I ran increased offset yokes (i.e. slow steering). It can also happen by too little preload on the shock, or the shock too short (i.e. robbed out of another type of GSXR - basically anything that causes it to turn slow and scrub itself 'round the corner. It might not be, could be other stuff, just a thought ...

Wear on the rear looks spot on.

I think you are spot on here. Its geometry definitely I think. Its a Y/K1 750 with a K4 750 fork and K5 1000 rear shock. Strangely though it never did this with the Pirelli SC1

Either ways I know there is an issue. I have the Comp and Rebound on max hard and pre load set 1 1/2 turns from max in to try and firm it up but its just masking a problem. MCT cant get me in until October so I have emailed FTR and tyres4bikes who can sort my forks and supply another tyre at a decent price. Will see what they both say, got 2 weeks to sort it

Yep, this is a geo tear..
There's no way you should have the comp & reb wound right in. And they're fast or slow, not hard or soft
With the rebound wound in, when you brake for a corner the front compresses and doesn't return. This is changing the front geo and causing the front to be overloaded and push around the corner.
and setting preload all the way down doesn't change the spring rate, juust the initial pressure/load required to get it moving.
Whatever chop told you to wind the rebound in needs a decent smack in the gob, it's the quickest way to see your arse.... it's frankly fking dangerous. Rebound is THE MOST important suspension adjustment and nees to be fairly quick, or "open" to allow the wheel to follow the road effectively.
You don't need to go to MCT if you're not changing out components, you can set the suspension yourself.
And when swapping between different tyres or tyre manufacturers, watch out for any differences in tyre height. just becasue a tyre says 190/55 doesn't mean it's the same height as another make 190/55. This difference will change the bikes rake and turn in feel.