Author Topic: Suspension mods for forks  (Read 12080 times)

Offline XR6

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Suspension mods for forks
« on: April 20, 2015, 10:58:42 PM »
Has anyone modified the valving in the front forks. e.g. Changed the shim stacks and then tried softer springs, different fork oil etc to get better handling out of the front.
I understand that there are Traxxion Dynamics kits available ( expensive) just wondering if maybe there is a cheaper way to modify?
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Offline Spanky

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Re: Suspension mods for forks
« Reply #1 on: April 21, 2015, 11:56:04 AM »
I have read some people have been happy with the race tech gold valves. Many have also purchased zx14 forks on ebay and had them re-valved. This option will give you even more adjustablility.

Offline B.D.F.

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Re: Suspension mods for forks
« Reply #2 on: April 21, 2015, 12:08:02 PM »
ZX 14 forks fit a C-14, at least up to the 'R' model anyway. ZX forks have compression damping adjustments which is a real plus IMO. The springs in a ZX are quite a bit lighter than the springs in a C-14 but they will work; I have them on my bike right now and have put several thousand miles on it as it is. That said, I think a spring rate about 1/2 way between the spring rate of a ZX and the spring rate of the C-14 would be excellent, at least as I use the bike.

ZX 14 forks can be had occasionally as 'new take-offs', meaning they are brand new but removed from a ZX that may be a few years old; mine were purchased last year but came off a 2011 ZX 14. Price was around $400 for the forks, and a set of springs would be around $100 or so, and the tool set needed to R&R the springs would be again around $100 or so.

Brian

Has anyone modified the valving in the front forks. e.g. Changed the shim stacks and then tried softer springs, different fork oil etc to get better handling out of the front.
I understand that there are Traxxion Dynamics kits available ( expensive) just wondering if maybe there is a cheaper way to modify?
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Offline XR6

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Re: Suspension mods for forks
« Reply #3 on: April 21, 2015, 01:53:20 PM »
BDF how do you use your bike?  I use mine a lot two up and also two up loaded.  How have the zx14 springs handled the xtra load when two up?

I see the springs are .95kg (zx) vs 1.2 kg (std)

I was talking to a suspension guru and said he would "never put in anything more than a 1.05kg in forks".  0.95kg from the zx might be very close to the mark.  Maybe a 1.05kg (approx) might be good for two up?

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Offline B.D.F.

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Re: Suspension mods for forks
« Reply #4 on: April 21, 2015, 02:01:54 PM »
I also ride two- up and loaded a lot. I do not find that the load on the bike is all that important to the front suspension set up though, it is very much more important to set up the rear suspension; most of the added load on a motorcycle is very well toward the rear.

That spring sounds just about right to me, as I said, I would go 1/2 way between the stock ZX and C-14 springs, and 1.05 is just about perfect I think. Another thing you can do is drop the viscosity of the fork oil and then adjust both the compression and rebound damping given ZX 14 forks; I think that would be a much better setup than the factory C-14 forks.

I bottomed out the front end once or twice before dialing up the compression damping, which worked very well for me. The spring pre- load is set to the max., and the ride quality is MUCH better than the stock forks, which I find too stiff both in spring rate as well as damping.

Brian

P.S. I want FULL CREDIT for not putting in one single smarta$$ answer regarding 'how I ride my bike' (mostly forward, tires down, etc., etc.) as well as not putting a single 'Easy Boys' anywhere after mentioning the stiffness of the damping.  ;D



BDF how do you use your bike?  I use mine a lot two up and also two up loaded.  How have the zx14 springs handled the xtra load when two up?

I see the springs are .95kg (zx) vs 1.2 kg (std)

I was talking to a suspension guru and said he would "never put in anything more than a 1.05kg in forks".  0.95kg from the zx might be very close to the mark.  Maybe a 1.05kg (approx) might be good for two up?
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Offline maxtog

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Re: Suspension mods for forks
« Reply #5 on: April 21, 2015, 03:36:58 PM »
P.S. I want FULL CREDIT for not putting in one single smarta$$ answer regarding 'how I ride my bike' (mostly forward, tires down, etc., etc.) as well as not putting a single 'Easy Boys' anywhere after mentioning the stiffness of the damping.  ;D

I grant to you said credit
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Offline jsa

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Re: Suspension mods for forks
« Reply #6 on: April 21, 2015, 07:41:57 PM »
I have 40K miles on ZX-14 forks I bought on eBay for $250.  I added 1.0 kg springs from Sonic Springs, an additional 8mm of internal spacers to compensate for the different length springs, and 85/150 SS fork oil.  I weigh 225 and have never bottomed the forks.  The ride is very plush and probably about 95 percent as good as it's going to get even if I were to have it revalved.

Adding weight on the  back seat doesn't increase the fork spring requirements, a much heavier rider (over 300 lbs) probably will although heavier riders usually like the OEM forks.

If you are interested in doing the ZX-14 fork upgrade, they are not tapped for the C14's ABS sensor.  It's easy to fix but requires a drill press and a couple of sharp drills.
« Last Edit: April 21, 2015, 10:13:17 PM by jsa »

Offline XR6

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Re: Suspension mods for forks
« Reply #7 on: April 21, 2015, 11:14:24 PM »
Well done Brian, FULL credit given.
Just to make sure I understand..... The forks off the ZX14 you have are stock std,  as taken off the ZX14, no mods.
I am encouraged that you can use the ZX14 stock standard and play with the dampers


JSA.... thanks,  sounds like trying the ZX14 forks std first ( I  weight 190 solo/363 two up no luggage . Then maybe add the 1.0 kg spring only if needed. What brand is the 85/150 oil? Is that Maxima 5w

Yes, I am aware that I need to drill and tap the right hand side for ABS. No problems there. Thanks
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Offline XR6

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Re: Suspension mods for forks
« Reply #8 on: April 21, 2015, 11:18:14 PM »
BDF  Have you changed your rear shock from standard.
I have a new Nitron rear shock arriving any day now from the UK
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Offline The Pope

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Re: Suspension mods for forks
« Reply #9 on: April 22, 2015, 05:01:41 AM »
Just to clarify things....... the front ABS sensor on 08/09 C14's is different than the one used on 2010+ C14's. While you can just drill and tap what's needed to mount the ABS sensor for the 08/09's, you have to make modifications to the ABS sensor and make and adaptor to be able to mount it to a ZX14 fork (this includes aftermarket forks like Ohlins) you're mounting on a 2010+ C14.

I've got Ohlins ZX14 forks on my 2011 C14 and can assist anyone with more information if needed.
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Offline jsa

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Re: Suspension mods for forks
« Reply #10 on: April 22, 2015, 09:21:03 AM »


JSA.... thanks,  sounds like trying the ZX14 forks std first ( I  weight 190 solo/363 two up no luggage . Then maybe add the 1.0 kg spring only if needed. What brand is the 85/150 oil? Is that Maxima 5w

Yes, I am aware that I need to drill and tap the right hand side for ABS. No problems there. Thanks

You can use the stock ZX14 springs and one of my friend's does, we added about 10mm of internal spacers to keep the ride height consistent.  His ride is very plush, I think my bike handles a bit better.  I use Golden Sprecto fork oil, any 85/150 suspension fluid will work as well as any 5wt but you are never sure what viscosity you  are getting with 5wt oil since it varies by brand,  Maxium 5wt is the right viscosity.

Offline jsa

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Re: Suspension mods for forks
« Reply #11 on: April 22, 2015, 09:24:46 AM »
Just to clarify things....... the front ABS sensor on 08/09 C14's is different than the one used on 2010+ C14's. While you can just drill and tap what's needed to mount the ABS sensor for the 08/09's, you have to make modifications to the ABS sensor and make and adaptor to be able to mount it to a ZX14 fork (this includes aftermarket forks like Ohlins) you're mounting on a 2010+ C14.


I thought it was a lot easier and "cleaner" to use 2 different size drill bits to duplicate the hole on the C14 forks to accept the ABS sensor without modifications.

Offline B.D.F.

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Re: Suspension mods for forks
« Reply #12 on: April 22, 2015, 09:26:52 AM »
Exactly right- I am using stock 2011, ZX 14 forks without any modification at all. Spring pre- load is all the way down.

Compression damping adjustment makes a huge difference, it will go from mushy to harsh in one turn of the adjusting screw.

Brian

Well done Brian, FULL credit given.
Just to make sure I understand..... The forks off the ZX14 you have are stock std,  as taken off the ZX14, no mods.
I am encouraged that you can use the ZX14 stock standard and play with the dampers


JSA.... thanks,  sounds like trying the ZX14 forks std first ( I  weight 190 solo/363 two up no luggage . Then maybe add the 1.0 kg spring only if needed. What brand is the 85/150 oil? Is that Maxima 5w

Yes, I am aware that I need to drill and tap the right hand side for ABS. No problems there. Thanks
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Offline XR6

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Re: Suspension mods for forks
« Reply #13 on: April 22, 2015, 12:49:34 PM »
Brian
How many adjusters do the ZX forks have for compression? It looks like there are 2x
High speed and Low speed?

Which one did you adjust to stiffen up the front?


Compression damping adjustment makes a huge difference, it will go from mushy to harsh in one turn of the adjusting screw.

Brian

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Offline B.D.F.

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Re: Suspension mods for forks
« Reply #14 on: April 22, 2015, 10:16:52 PM »
One compression damping adjustment, located at the bottom / rear of the fork. The boss is there for the valve on a C-14 but it is not machined and of course, there is no valve installed. The ZX 14 forks have the identical rebound adjustment on the top of the forks that the C-14 has, and the spring pre- load adjustment is the same on both fork types as well.

Turning the bottom, compression valve increases the compression damping; this makes the forks more difficult to move quickly and damps the fork contracting or compressing. If it is too light, the forks compress too quickly and too much over relatively small undulations in the road surface, and the bike will also suffer from brake dive. Too much and the ride is harsh.

Rebound adjustment is quite different and I think, more difficult to get adjusted for best performance. Then again, its overall impact (no pun intended) on overall riding is less than compression adjustment- I am really surprised that Kawasaki left rebound damping adjustments on the C-14 but removed compression damping.

Brian

Brian
How many adjusters do the ZX forks have for compression? It looks like there are 2x
High speed and Low speed?

Which one did you adjust to stiffen up the front?
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Offline XR6

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Re: Suspension mods for forks
« Reply #15 on: April 22, 2015, 10:47:29 PM »
 
I am really surprised that Kawasaki left rebound damping adjustments on the C-14 but removed compression damping.

Brian


I recon KAWASKI  has this wrong too, Why does the ZX14 have reb, comp in the front, rebound, comp in the rear, but not on the C14. We probably have more demands and extremes than the ZX14 has when I comes to loading 2 up with luggage and then also solo!  quite a contrast in demands on suspension, yet Kawaski chooses to leave this off!!!!!!!!?????? :nuts: :doh:  The cost can't be that much differance.

Ok.......     I have said my bit and will get off the soap box now.
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Offline The Pope

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Re: Suspension mods for forks
« Reply #16 on: April 23, 2015, 03:18:09 AM »
I thought it was a lot easier and "cleaner" to use 2 different size drill bits to duplicate the hole on the C14 forks to accept the ABS sensor without modifications.
If you're replacing the forks on a 2008 or 2009 C14 all you have to do is to drill the two holes (tap the one for the bolt). For 2010+ C14 Kawasaki changed the sensor, so it's not as simple.

The distance from the center of the sensor to the center of the mounting hole in the sensor is different between the 08/09 vs 2010+.

Also, you can't just use the ABS sensor from a 08/09 on a 2010+. The connecting plugs and wiring are different.

Take a look at this thread: http://www.zggtr.org/index.php?topic=17447.msg216627#msg216627
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Offline VirginiaJim

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Re: Suspension mods for forks
« Reply #17 on: April 23, 2015, 04:11:22 AM »

I recon KAWASKI  has this wrong too, Why does the ZX14 have reb, comp in the front, rebound, comp in the rear, but not on the C14. We probably have more demands and extremes than the ZX14 has when I comes to loading 2 up with luggage and then also solo!  quite a contrast in demands on suspension, yet Kawaski chooses to leave this off!!!!!!!!? ??? ?? :nuts: :doh:  The cost can't be that much differance.

Ok.......     I have said my bit and will get off the soap box now.

I'm thinking that they think that giving us three adjustments to worry about was too complicated and based on the questions here and my thoughts on the subject, I think that they maybe they're right.
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Offline jsa

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Re: Suspension mods for forks
« Reply #18 on: April 23, 2015, 05:15:58 AM »
If you're replacing the forks on a 2008 or 2009 C14 all you have to do is to drill the two holes (tap the one for the bolt). For 2010+ C14 Kawasaki changed the sensor, so it's not as simple.

The distance from the center of the sensor to the center of the mounting hole in the sensor is different between the 08/09 vs 2010+.

Also, you can't just use the ABS sensor from a 08/09 on a 2010+. The connecting plugs and wiring are different.

Take a look at this thread: http://www.zggtr.org/index.php?topic=17447.msg216627#msg216627

I think we have different opinions how to drill the mounting hole(s) and install the (unmodified) sensor from a 2010+ C14  to a standard ZX-14 right fork because I have actually done it....as have 2 of of my friends.
« Last Edit: April 23, 2015, 08:23:01 AM by jsa »

Offline The Pope

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Re: Suspension mods for forks
« Reply #19 on: April 23, 2015, 10:16:15 AM »
Ok.
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