Gen 4 Undersprung vs oversprung - Kawasaki ZX-10R.net
 
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post #1 of 10 Old 08-05-2012, 04:51 PM Thread Starter
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Gen 4 Undersprung vs oversprung

Hi everyone, I have been lurking and searching on this site for a couple of weeks trying to learn as much as I can about my new used 2011 ZX10R, but have not been able to find an answer to the questions I have. I am planning on having the rear shock resprung for my weight (165 lbs with out gear), and revalved. According to RaceTech's site, I need a 10.994 kg/mm spring for street or 11.2 for road racing. However they only offer a 10.7 0r 11.6 spring. All I do is street riding, and sometimes aggressive street riding, also I don't mind a stiff ride at all. I was planning on keeping the factory spring rate in the forks, but RaceTech's site recommends to change those to .944 for street riding or .991 for road racing from 1.0 kg, but they only offer .95 kg so I would be again oversprung or undersprung in the front (but not by much). I have yet to locate a reputable shop in my area to help me set up my suspension, but I am working on it. Any advice or help is appreciated. My questions are:

1) generally is it better to be oversprung or undersprung?
2) Would it even be worth doing the front at all?

Last edited by rayanb; 08-05-2012 at 04:55 PM.
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post #2 of 10 Old 08-05-2012, 09:46 PM
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For street riding, unless you are doing stuff that is gonna get you killed, you are not gonna notice the difference between 0.944 (calculated) and 0.95 (closest available) and 1.0 (stock). Nor are you going to notice the difference between 10.7, 10.994, and 11.2 on the rear.

For street riding, which means the real world of potholes and expansion joints and frost heaves and broken pavement (around here), I prefer to use the most compliant setup that I can get away with (that doesn't cause bottoming).

Do the zip-tie test. Put a zip-tie around your fork just below the lip of the fork seal and tension it as tight as you can then go for a typical ride. This will tell you how much travel you are actually using. You want to stay out of the last 20-ish mm of front fork compression to avoid being in the hydraulic bump limiter (the compression damping intentionally becomes extremely high in the last few millimeters of travel to minimize actual mechanical bottoming). I'm not sure of the exact dimension where the bottoming damping starts activating on these forks, perhaps someone else has that information - or you can find out yourself by temporarily putting the forks together without springs and just feeling the way the compression damping acts.

You can do something similar on the rear shock but the usual trick is to assemble the shock with an O-ring on the shaft.

I'm going through this right now with my race bike (not a zx10r) - I've discovered that the rear shock is bottoming out on the deteriorated pavement of some of the tracks around here ...


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post #3 of 10 Old 08-05-2012, 10:40 PM
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At 165lbs I'd bet you're pretty close to the target weight they designed the rear shock for.

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post #4 of 10 Old 08-06-2012, 12:29 AM
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No need to mess with the Front "At All"
The BPF forks are Very stiff natured. Unless you were 250#'s
the leave it alone

The Rear--
Go with a 600# spring (imo)
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post #5 of 10 Old 08-06-2012, 04:32 PM Thread Starter
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Thank you guys for all the responses. Going to just get the rear shock reworked in case I decide to do track days.
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post #6 of 10 Old 03-06-2013, 08:06 PM
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Anybody use the Race Tech SRSP 5818 Rear spring on the Gen 4 according to race techs site the rear shock is sprung for a rider around 140 lbs so me weighing in at 205 its a little under sprung. just looking for some feed back

2011, guhl flash and tune,k&N race spec,Graves ti. 3/4 slipon,1/5 turn insert,-1+2 sprockets,tech spec tank pads,hotbodies venom windscreen,T-rex racing fork and frame sliders, 55w hids,Ivans block off plates,Black Pro bolt kit, Speigler braided brake lines, Mikey Moto lightweight rear rotor.CRG RC2 shorty levers, Suspension Technologies reworked shock
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post #7 of 10 Old 03-06-2013, 09:42 PM
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I am guessing you have already tried to set your sag and cant get it right since your talking respringing. I would say if you can get between 30 and 35 mm of sag you should be fine.

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post #8 of 10 Old 03-09-2013, 04:54 PM
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Quote:
Originally Posted by meanstreak5 View Post
I am guessing you have already tried to set your sag and cant get it right since your talking respringing. I would say if you can get between 30 and 35 mm of sag you should be fine.
ok cool i checked the sag it was 39 front 36 rear so i set them both up to 33 and ill try that before re springing

2011, guhl flash and tune,k&N race spec,Graves ti. 3/4 slipon,1/5 turn insert,-1+2 sprockets,tech spec tank pads,hotbodies venom windscreen,T-rex racing fork and frame sliders, 55w hids,Ivans block off plates,Black Pro bolt kit, Speigler braided brake lines, Mikey Moto lightweight rear rotor.CRG RC2 shorty levers, Suspension Technologies reworked shock
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post #9 of 10 Old 03-09-2013, 05:48 PM
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I love suspension talk.
Keep us posted.
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post #10 of 10 Old 03-10-2013, 01:45 AM
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Stay closer to the street values unless you're rather fast on the track and actually on the track ;)

Also, don't forget your option to mix it up (1x 1.00kg spring & 1x 0.95 spring = 0.975 front end).


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