[Ambar]

Has anybody tried lowering the fork tubes in the triple tree. To extend the forks out farther?
There’s about 1cm left on the fork tubes before they top out.
I’m a heavy set guy (must be breaking the 110kg/240lb mark all geared up) and have bolted a fair bit of gear onto my Z650, including some hard luggage on the back.
I managed to preload my rear shock (just one click up) to try and tidy up the suspension and it has helped quite a bit. But there is no preload adjustment for the front forks and I feel like it might be sagging down.
When at speed (+100km/h), the front end starts feeling light and vague.

Best solution would surely be to upgrade the springs, but short of spending money and going crazy on shocks, does anybody know if extending out the 1cm would give me enough of a trail boost to change the stability of the bike at speed?

 

[POWERMAN]

Im curious - how would you go about extending the forks in order to give yourself more play wirh suspension travel?
All this time I was under the impression that front suspension modification was not possible without swapping components internally and such...

 

[Ambar]

Hey Powerman, sorry, My first post might've been a little confusing, It's a little tricky to explain but let me see If I can make myself clearer.
Yep! Our forks have no adjustment per say. My idea is to open up the triple clamp and slide the forks down a bit.
Under careful observation, my bike came from factory with about 1cm of fork tube protruding from the top of the triple clamp. I found a picture online that shows this quite clearly.

The thought behind this is that by doing so, I can have the bike sit slightly higher on the suspension under load.
Another way to think about this is that I'll be extending my wheels further out from the handlebars. Increasing the wheel base and rake slightly, and thus increasing the trail as well (or so I suspect).

I've seen a few videos online of Dave Moss tuning the suspension of the MT(FZ)-07. With that bike he's trying to fix a different problem, but this was one of the possible parameters.
(In the video, the owner had the suspension out as I'm describing, and once he revamps the suspension, he opts to bring the forks back in to different spec).

To be clear, I'm fully aware that this will not increase the suspension travel, nor is it adjusting anything about the fork behaviour.

What I'm trying to understand is if this is enough to make a difference (I suspect it is), how much should I do, and whether I'll achieve a positive result towards my goal which are two-fold:
1 adjust the light, vague feel at speed.
2 tame the front end dive breaking into corners.

And of course! I'm all open for suggestions on easier, better, and/or cheaper ways to address this problem..

 

[POWERMAN]

Interesting!

I am by no means an experienced when it comes to things like this.
However, if it was me, I'd look into swapping in a cartridge kit or springs...not exactly cheap, but give me peace of mind at the very least.

Plus a slightly stiffer kit would address both these issue for you, no?:
1 adjust the light, vague feel at speed.
2 tame the front end dive breaking into corners.

This is what came up when I did a search:

New suspension for 2017 Kawasaki Z650 ABS

Front and rear products now available for Kawasaki Z650!

www.bitubo.com

Ohlins NIX22 Cartridge Kit Kawasaki Z650 / Ninja 650 / ER6n - RevZilla

Many OEM forks only allow for a small range of adjustments and some offer none at all. This can be very frustrating as many riders’ skills eventually …

www.revzilla.com

Hyperpro Suspension for the new Kawasaki Z650 2017! - Hyperpro

Last year Kawasaki presented the brand new Z650 as a replacement for the popular ER-6 (NINJA 650). The bike has been completely changed from the inside as well as from the inside and looks great. In order to make the bike ride as sharp as it looks, Hyperpro developed a wide range of suspension...

hyperpro.com

Sorry I am not of much help..hopefully someone else with more experience will chime in !

 

[Carvalho Ciclismo Eduardo]

I made these inserts - actually, I made 3 different lengths of them - to act as preload bushings.
Each one sits upside down, on top of each spring, then the fork caps squeeze them against the springs. Still need to ride some twisties and find out if they work well or not.

 

[Carvalho Ciclismo Eduardo]

BTW, Google for “race tech gold emulator valves”

if preload works fine with my experiment, next step will be a pair of emulator valves

 

[Ambar]

That’s a cool idea!
I like wrenching on my bike but I figured this job is beyond my tools and skills so I ended up taking my bike to a specialized shop. They said they modified the springs for higher preload and serviced the fork oil.
It really feels like everything changed about the bikes front end.
Just had a weekend trip on the bike with all kinds of condition, long and windy straights, tight twisty road with terrible road conditions, and long sweeping high speed. Though the rides feels a little harsher (to be expected) it feels vastly more stable! All while having a full top case hanging off the back.

 

[Carvalho Ciclismo Eduardo]

“All while having a full top case hanging off the back.”

actually, in this case, I would have changed the rear spring as well.