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Author Topic: Need some suspension advice 2008 Hayabusa Turbo street  (Read 9459 times)

Offline jgennaro

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Need some suspension advice 2008 Hayabusa Turbo street
« on: December 01, 2011, 12:47:08 PM »
Members,

I'm looking for some advice regarding a front tire "wobble" that I've noticed over 150MPH.  Let me give you the background first.  I have an 08 Busa which has a turbo kit and is stock height and length.  The riding I do is mostly Sunday riding with some twisty roads, sweepers, and once in a while top end stuff over bridges and long straight roads.

The other day I noticed the front become unstable at around 150.  What I mean by this is the front end seemed to shake left to right above 150MPH on a flat straight road.  I never really noticed this issue until I adjusted the suspension a few months ago.  I followed the recommendations from this site:

http://www.sportrider.com/suspension_settings/suspension/146_1004_sport_rider_suspension_guide/index.html

Here are the measurements:

Front
L1-136.52mm
L2-85.72
L3-87.32
 
Sag with my weight 50mm
 
Rear
L1-349.24mm
L2-323.84
L3-323.84
Sag with my weight 25.4mm
 
 
Here are my settings after measuring and testing:
 
Front
Preload added 5.75 turns........ all the way stiff.  I did this because I really need heavier springs. I also dropped the front end 5mm to compensate.
Rebound 7 out is stock and is set at 4 clicks out
Compression 7 out is stock and is set at 7 clicks out
 
Rear
Preload....stock
Rebound stock is 11 out and is set at 10 out
Compression stock is 7 out and is set at 4 out

These settings seemed to work great for twisty roads but I think are a little too stiff for high speed.  I was going to soften the front and rear up a little to see if that helps with the high speed instability and check the front tire to make sure it's not separated or out of balance.

Does anybody have suggestions or recommendations regarding my suspension settings?  Any help here is appreciated since I really don't know much about suspension set-ups.

Jason 
Speed, it seems to me, provides the one genuinely modern pleasure.

Aldous Huxley 1894-1963
 
2008 Hayabusa
Ninja 250.........daily driver

Offline Kirk

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #1 on: December 02, 2011, 05:35:33 PM »
Jason, you didn't include your weight, your bike's weight, your front and rear tire size/brand/model, and how many miles on your tires.

50mm sag is WAY too much up front.  There is no adjustment that you're going to be able to do to the front with the wrong springs in it.  That would be like trying to "adjust" the cat box so it doesn't smell.  It's just not gonna happen- you need to make a change.  With the stock springs and valving, you'll blow through the remaining travel so fast, your REAL front suspension is the internal compression bump stops.  And under any real braking, the front end will fall like a fainting goat. It's just not safe.

And you're gonna need a wee bit more sag in the back- about 5mm more (28-32mm- shoot for 30mm).  Under acceleration, the chain will try to top out the rear suspension.  With the additional power of a turbo, it may be trying REALLY hard.  With too little sag, you may be letting it top the rear suspension out, rendering the rear end rigid. If it's absolutely TORCHING the rear tire on top speed runs, you may have found at least one component of your problem.  Depending on your weight, you may find the rear spring is too stiff- but the front end needs WAY more help than the back end.

Suspension issues aside, you may have a tire issue.  If you're running any tire OTHER THAN a non-N-Tec U. K.-made Dunlop race tire, your bike should be TOO stable, and it should just get worse the faster you go, to the point that (with stock wheels) you will lack the upper body strength to make significant changes in direction at top speed.

I don't trust clip-on rim weights.  For years, I have used only tape weights, and then put duct tape over them.  You'll NEVER lose one if you do it that way.

You're probably going to want a dual-compound tire, because of the turbo and the top-end stuff.  Otherwise you'll be replacing flat-spotted tires every time you turn around.  They're no fun to ride when you don't need a kick-stand to park it.

Front tires that are prematurely cupped from trying to ride on the stock fork springs, can ride really strange.  If I had to guess, I'd guess that this is the direction that all of this is going.  And sacrificing more new front tires to the flaccid OEM fork springs is not the answer- it will simply put your bike right back into the condition it was in immediately prior to it becoming unrideable.

Your bike is trying to warn you.  That warning can save your life if you heed it and take appropriate action.  If you ignore it, you need to remember that this sport is played by "Big Boy" rules.
« Last Edit: December 02, 2011, 06:15:16 PM by Kirk »
-Kirk

Offline jgennaro

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #2 on: December 07, 2011, 08:15:32 AM »
I ended up taking the bike to a suspension professional.  The pro replaced my front springs and set-up the suspension.  He also found the front tire to be out of balance.

I haven't had an opportunity to get it up to speed yet.  Time will tell if that does the trick. :tu:

Jason
Speed, it seems to me, provides the one genuinely modern pleasure.

Aldous Huxley 1894-1963
 
2008 Hayabusa
Ninja 250.........daily driver

Offline Kirk

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #3 on: December 07, 2011, 11:40:01 AM »
Cool. 

What springs did he install?
-Kirk

Offline Kirk

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #4 on: December 07, 2011, 11:42:38 AM »
Jason, you didn't include your weight, your bike's weight, your front and rear tire size/brand/model, and how many miles on your tires.

-Kirk

Offline jgennaro

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #5 on: December 07, 2011, 01:04:00 PM »
Cool. 

What springs did he install?

1Kilo
Speed, it seems to me, provides the one genuinely modern pleasure.

Aldous Huxley 1894-1963
 
2008 Hayabusa
Ninja 250.........daily driver

Offline Kirk

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #6 on: December 07, 2011, 02:04:56 PM »
Still wondering about these other items:

Jason, you didn't include your weight, your bike's weight, your front and rear tire size/brand/model, and how many miles on your tires.



...but that's a HUGE step forward.  Set your sag to 28-32 in the back, and 32-36 in the front, adjust your rebound, and then you can start riding it and finding where you like the compression damping set at. I'm happy for you- I think you're really gonna dig it.

Here's a tutorial on setting your sag and rebound:

http://www.suzukihayabusa.org/forum/index.php?topic=75350.0
-Kirk

Offline Kirk

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #7 on: December 07, 2011, 02:29:35 PM »
The next step is brakes.  It's easy, it's cheap, you can do it yourself, and it will make you feel like Superman, ESPECIALLY after doing the front springs and adjusting your suspension.  After I did it, I was kicking myself in the head, trying to figure out how (and why) I ever rode it before.

The following tutorial was written on the Gen I Hayabusa brakes:


http://www.suzukihayabusa.org/forum/index.php?topic=75357.0


Your bike is a Gen II, so the part numbers will be different.

The correct part number for the EBC HH sintered front brake pads for the Gen II is FA379HH.

The "kit" race version of the above pads are part number GFA379HH.  The "kit" race pads work about the same as the regular HH pads below 150 mph, and feel stronger than the regular HH pads above 150 mph.  

The EPFA379HH is their "Extreme Pro" version of the "kit" race HH pads, and if I understand it correctly, it's even more powerful than the regular "kit" race pads.

The GPFA379HH is even more powerful than that, the MOST powerful "kit" race pads that they make, and they caution about using them on the street.  These would be the ones that I would use on a turbo Hayabusa with good suspension and tires.  :wink:

A word of caution- these pads will give you that "Hand of God" stopping power, like a jet fighter catching a 3-wire on a carrier deck.  You'll need to take time to become accustomed to having that much power available.  The kind of braking power we're talking about here is the ability to lift the rear tire off the ground at ANY speed, using just your pinkie.  

Their authoritative initial bite is really confidence inspiring when you're going really fast, and for as powerful as they are, they are also very linear and predictable. They also give great feedback, including audible feedback, they are very fade-resistant, the last a long time, they're inexpensive, they're EASIER on the rotors than even the stock brake pads, and they leave virtually NO brake dust on the wheels.  They're just plain awesome.  :D
« Last Edit: December 07, 2011, 02:31:50 PM by Kirk »
-Kirk

Offline jgennaro

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #8 on: December 07, 2011, 07:45:10 PM »
Still wondering about these other items:

Jason, you didn't include your weight, your bike's weight, your front and rear tire size/brand/model, and how many miles on your tires.



...but that's a HUGE step forward.  Set your sag to 28-32 in the back, and 32-36 in the front, adjust your rebound, and then you can start riding it and finding where you like the compression damping set at. I'm happy for you- I think you're really gonna dig it.

Here's a tutorial on setting your sag and rebound:

http://www.suzukihayabusa.org/forum/index.php?topic=75350.0

I weigh about 200 and I'm not sure what my bike weighs.  I would say about 20lbs more than stock with the turbo, extra water, and plenum but that's just a guess.  The tires I have are whatever the bike comes with stock in the front and a Shinko in the rear.  That's going to change soon to a Power One.  I'll probably also put in raising links in the back at the same time.

As far as adjusting goes........I'm out.  I just let my suspension guy do it.  He's been doing it for years and I trust his judgement. 

Regarding brakes.......mine work great with HH.  Honestly I don't see the need to change something that works great.  The only thing I'm going to do is spend more time riding, raise the rear, and get new tires by March.  THAT....will make me happy.

Thanks for your input.

Jason 
Speed, it seems to me, provides the one genuinely modern pleasure.

Aldous Huxley 1894-1963
 
2008 Hayabusa
Ninja 250.........daily driver

Offline Kirk

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #9 on: December 07, 2011, 08:10:46 PM »
Your bike might actually be a little lighter than stock- that stock exhaust system that you took off to install the turbo weighed about 40 pounds.

I didn't realize that you already had HH pads.  :wink:

The Power One is a street-legal TRACK DAY tire- It would be unlikely that you'd ever get it hot enough to stick, and it won't last very long.  

The Power Pure is a "hypersport" street tire that you can use on the track.  The Power Pure will probably give you better traction AND last longer.  

They are both dual-compound tires, with harder rubber in the middle (to help the tire last longer) and softer rubber on the shoulders (to give you extra traction when you're banked over), which would be good for a turbo bike.  

They both come in several sizes designed for your 6" rear wheel: 180/55ZR17, 190/50ZR17, and 190/55ZR17.  All three sizes have the same load rating.  I would strongly recommend NOT using the OEM 190/50ZR17 size.  The 180/55ZR17 and the 190/55ZR17 will both help the handling and make the bike feel much lighter, as well as putting more rubber on the road when banked over, giving MUCH more traction.  The 180/55ZR17 is going to be lighter, less expensive, quicker on acceleration, and quicker to change direction.  The 190/55ZR17 will give you almost all of the handling improvements of the 180/55ZR17, but it will give even more traction and last longer.  On a turbo bike, I'd probably go with the 190/55ZR17 Power Pure.



« Last Edit: December 08, 2011, 06:41:57 PM by Kirk »
-Kirk

Offline Over200

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #10 on: December 17, 2011, 09:37:22 PM »
Hey jason..Long time..sounds like you have things under control...you can always hit up thermosman or Brad Stokes at Ohlins in NC...The only guys that touch mine! Hope to see you soon.

H
How much for the whole pie...2..3..4..5?

Offline Kirk

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #11 on: December 17, 2011, 09:49:07 PM »
I don't know Brad, but I'm sure he's qualified to be doing this kind of stuff, and of course Mike has been doing this forever.  I've used GP suspension- there's a lot of places to get qualified help with this stuff.  :)
-Kirk

Offline Kirk

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #12 on: December 17, 2011, 09:50:45 PM »
So, Jason, what's the scoop?  The answer shouldn't be any further away than the nearest freeway onramp, lol.  :lol:
-Kirk

Offline jgennaro

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #13 on: December 18, 2011, 12:50:53 AM »
Hey jason..Long time..sounds like you have things under control...you can always hit up thermosman or Brad Stokes at Ohlins in NC...The only guys that touch mine! Hope to see you soon.

H

Howard,

You're still alive....holy shit!
Speed, it seems to me, provides the one genuinely modern pleasure.

Aldous Huxley 1894-1963
 
2008 Hayabusa
Ninja 250.........daily driver

Offline jgennaro

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #14 on: December 18, 2011, 12:54:17 AM »
So, Jason, what's the scoop?  The answer shouldn't be any further away than the nearest freeway onramp, lol.  :lol:

Kirk,

I wish it was that easy!  I had rain since the service and for the last two weeks I've been stuck in Maryland for work.  The short answer is no........I haven't has an opportunity to 'test' it out.

Jason
Speed, it seems to me, provides the one genuinely modern pleasure.

Aldous Huxley 1894-1963
 
2008 Hayabusa
Ninja 250.........daily driver

Offline Kirk

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #15 on: December 18, 2011, 11:45:15 AM »
Well, I wish you the best, buddy.   :tu:
-Kirk

Offline Over200

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #16 on: December 18, 2011, 12:15:57 PM »
Hey jason..Long time..sounds like you have things under control...you can always hit up thermosman or Brad Stokes at Ohlins in NC...The only guys that touch mine! Hope to see you soon.

H

Howard,

You're still alive....holy shit!

Oh yeah..I couldn't be so lucky!..LOL..You still in the Hill?..I will be down in january for a visit.
How much for the whole pie...2..3..4..5?

Offline jgennaro

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Re: Need some suspension advice 2008 Hayabusa Turbo street
« Reply #17 on: December 18, 2011, 12:59:10 PM »
Hey jason..Long time..sounds like you have things under control...you can always hit up thermosman or Brad Stokes at Ohlins in NC...The only guys that touch mine! Hope to see you soon.

H

Howard,

You're still alive....holy shit!

Oh yeah..I couldn't be so lucky!..LOL..You still in the Hill?..I will be down in january for a visit.



Give me a call when you're in town bro.

Jason
Speed, it seems to me, provides the one genuinely modern pleasure.

Aldous Huxley 1894-1963
 
2008 Hayabusa
Ninja 250.........daily driver