Suspension adjustment question on SBK forks - advice sought

[Raux]

Well,
I've been out a few times with some serious riders and I just can't get the feel of the bike near their level.
The bike feels twitchy in the corners.
At slower speeds it's nice due to less effort to turn, but at higher speeds I feel the bike is nervous

I'm thinking the bikes is steering too fast, the front tucking on hard braking.
I am thinking about pushing the forks through the triple a bit to raise the front, slow down the steering and be a bit more stable in the corners...

I have about 10-15mm of available fork to work with (3 lines on the sbk forks)
I was going to try 5mm at a time or 1 mark at a time.


is my thinking right?
Will 5mm be that much of a difference to notice or should I start at ten?

[stopintime]

Are you sure you're able to "relax" at those speeds? (leaving it up to the bike to do it's thing)

I ask because for me that is THE determining factor when it comes to successful turns...

If you are, then I think (from my own experience) 10 mm or more will give you a clearer idea if you're on the right track. If it's too much - go back a little.

[Raux]

Well yes and no.

if I have good visibility of the road through the turn, yes.
if it's a blind corner, hell no.

but i do feel the tucking effect of the front end.
even standing still the effort to just turn the bars back and forth is so light.
wish I could have a racer ride it and give some feedback.

[stopintime]

Well then, maybe it's not adjusted quite right?

Front wheel overinflated?

If it isn't the bike - riding close to the limit tend to make us do things differently - nothing strange about that.

[IdZer0]

I'm certainly no expert so take my advice with a grain of salt.

If it feels twitchy at higher speeds and fine at lower speeds, I'd say indeed a bit more trail would be good idea (ie. raising the front as an easy option). I tried this myself just weeks ago and you do feel the difference of 5 mm. I suggest you try 10, then maybe go back to 5. Take your time to try it out (on the road before you try it out on track at high speeds), it feels very different.

And if you don't like it you can always go back.

[dlearl476]

My advice? Take it to a suspension expect. Tell them what it's doing, tell them what you want. As much as I've learned over the years, it pales in significance compared to someone who works on suspension 9-5/5 days a week and track days on weekends.
It will take them 1/2-1 hour to sort what will take you weeks by trial and error.

[Raux]

would love to take it somewhere, but the summer vacations took a toll on my pocketbook.

I'm just trying to get it that much better for now.

then maybe winter, it's suspension work and dynotune.

[koko64]

If preload and damping adjustments haven't helped much then raising the front 5mm at a time is worth a try.
On my old 900, I raised the rear about 25mm (10mm on the old hoop adjusters)to load up the front and give some more ground clearance, but had to raise the front 5mm. You have already loaded up the front by going to clipons, so if you raised the rear you could go back to stock or start raising the front. 5mm up on the front can make a substantial difference. My slappy old 900 doesn't need a steering damper now, it just gives the ocaisional twitch.

I was wondering if the position of the SBK forks as you have fitted them is on the "sharp" side to begin with.

[Speeddog]

What did you get done on the forks?
Springs?
What valving?
how much do you weigh?

[caperix]

I agree with speeddog, if the forks are not properly set up changing chassis geometry is not the place to start.  SBK forks are oversprung for most riders on a monster, so if they have not been changed springs may need to be swapped.  Get the suspension set up then decide if you still need changes.

[Link]

Not state the obvious but there wasn't much info in your post so.. I always start with the basics, Did you measure your stock set up prior to installing the forks ? That way you will have a base line to start from I would go back & start there. What rider sag numbers are you using front & rear ? I did the exact same fork swap & after I had bike back to the exact & I mean exact stock geometry numbers & sag set I started test riding. I found the front to seem a bit "light" or nervous so I ended up raising the rear aprx. 13mm (I tried the 1100 clevis but IMO it was too much). That helped, then I removed some rear preload, that helped, I finally ended up increasing the trail to about 101mm which is close to what most modern sportbikes run & that helped. The bike now rails with great feedback and very stable at speed. I think just raising and lowering your forks arbitrarily is not the answer a lot of guys will do this not really knowing WTF there changing. I think the 696 stock geometry numbers will allow you to go fast but the stock forks are the weak link on that bike and you fixed that. Go back to basics & keep notes it's easy to get lost when trying to set up a bike due too so many variables a small change in the rear can make a big change in the front ect. ect. ect.

[Raux]

ok I have a few answers.

didn't measure the stock. crashed

Fork specs:
The forks are professionally prepared by MRP Motorsports with the following upgrades:
 RaceTech G2-R 20mm Compression Valve
 RaceTech HFR(High Frequency Response) 20mm Rebound Valve
 RaceTech Ultra Slick fork oil
 Ohlins RT fork springs 9.5 N/mm

I've haven't measured the preload or rebound
I've backed off compression to 4 clicks from left

Ohlins guys at WDW were impressed with the setup.


Rear shock:
Stock Sachs
Preload 150mm
rebound: 4 click from left (soft)

I had the rear preload at 140mm for a while, but that was too much.


THe setup is as high as an 1100, but I do need to do some precise measurements to ensure I start at the 1100 front/rear setup.

I weigh 180 with gear.

Under hard braking I'll get with an inch of the bottom of the fork, and full panic stock will get with 1/2" of bottom.

I think the geometry is off but a bit due to the front being too short, but I will confirm that with some measurements Ungeheuer gave me for the 1100 stock setup.

[koko64]

Sounds like a good set up, done by experts. I'm envious.

Normally, .95 springs at your weight for a street bike could be harsh with stock bars, but your weight is over the front with clipons so a "sbk" rate of spring makes sense, Maybe a little less preload or compression damping?

Will be interesting to see Unges measurements.
At least raising the front is free and reversable.

[Link]

ok I have a few answers.

didn't measure the stock. crashed

Fork specs:
The forks are professionally prepared by MRP Motorsports with the following upgrades:
 RaceTech G2-R 20mm Compression Valve
 RaceTech HFR(High Frequency Response) 20mm Rebound Valve
 RaceTech Ultra Slick fork oil
 Ohlins RT fork springs 9.5 N/mm

I've haven't measured the preload or rebound
I've backed off compression to 4 clicks from left

Ohlins guys at WDW were impressed with the setup.


Rear shock:
Stock Sachs
Preload 150mm
rebound: 4 click from left (soft)

I had the rear preload at 140mm for a while, but that was too much.


THe setup is as high as an 1100, but I do need to do some precise measurements to ensure I start at the 1100 front/rear setup.

I weigh 180 with gear.

Under hard braking I'll get with an inch of the bottom of the fork, and full panic stock will get with 1/2" of bottom.

I think the geometry is off but a bit due to the front being too short, but I will confirm that with some measurements Ungeheuer gave me for the 1100 stock setup.

Well it sounds like your springs are to stiff or your front preload is to much, measure the rider sag you should be around 30mm to 35mm, prior to any suspension adjustment you must confirm your spring rate is correct and measuring rider sag is the only way to do that. No matter what you do to the suspension if you spring rate is wrong you will never ever get it right. I used race tech .9 springs and I'm also 180lbs not sure exactly how much preload I've got but sag numbers are good.

The stock rake and trail numbers for the 1100 are 24 deg rake and 96.52mm trail almost exactly what the 696 numbers are. Get the bike set at those numbers and go from there. There are a few web sites that show you how to measure trail. Due to you raising the rear and the sbk forks the only way to Know is to measure the trail, it's a pain the ass and takes some time but it's worth it. As I said increasing the trail to about 101mm worked well on my 696.

And try going soft on the rear I think that shock stiffens up at speed, set sag on the rear then start playing with preload

You fork mods are almost exactly what I had done there a good fork stock and a real good fork revalved. Once you get it set up right your bike will rail.

[koko64]

Hey Raux
Hows it goin'?
You sort it out?