K-Tech 20SSK-INT-SHO-15 Fork Piston Kit Installation in K9 750 - Suzuki GSX-R Motorcycle Forums Gixxer.com
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post #1 of 11 (permalink) Old 02-28-2017, 01:39 PM Thread Starter
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K-Tech 20SSK-INT-SHO-15 Fork Piston Kit Installation in K9 750

Bought the K9 750 early last year, and the suspension has never been right for me, undersprung and just really vague feedback from it. So I decided to start a thread to document the work to get it sorted by myself. K-Tech recommends having a suspension professional do the work, but I hate relying on others for things that I can and should be able to do for myself. And I've got Dave Moss in my backyard and at the track as a safety net if I get in trouble to assist me/take over.

I've got an older '03 R1 that Dave did with the previous owner that is absolutely planted, I want the K9 to be even better so that the only excuse is the rider being old and slow. So a thread to track the journey.

I always want MOAR info when I read these threads that I want to follow, so I'm hoping to keep a high level of detail/photos in here to follow the overkill that will be in this first post. Not sure where my post count needs to be to get links and photos in but I'll get to that level eventually.

Side note, I'll be doing the shock as well, Race Tech Gold Valve Shock Kit 40mm SMGVS 4005 ($145 shipped off ebay) is arriving Friday, Race Tech Rebound Separator Valve SMRS 1212500 ($65) already in hand, and a Race Tech 11.6 spring SRSP 5818116 ($120) is already installed on the shock. But it's never been serviced, so a separate thread for that will be coming when I dig into the shock later this spring.

First off is sorting the springs. I'm 6'4 252#. Bike is needs to be weighed once it's back together tomorrow. The Race Tech site shows that the optimum spring for anybody over 200-ish as 1.12kg/mm, which coverts to 11Nm. Problem is that RT spring options go from 1.0 to 1.4 which is a massive jump.

I found a set of Ohlins springs rated at 1.12kg/mm - 11N - Ohlins pn 004744-11 but the problem is that they measure 5.8mm shorter than my stock springs (stock rate is 9.8Nm).

So if I want to mix springs in the front to get to various custom spring rates I'll need to get my buddy with the lathe to make up some spacers with an additional 5.8mm in length to replace the "JOINT, SPRING UPPER" (see Partzilla link below) which is PN 51175-22D00, $11.70 to keep the Ohlins at a stock length.

The Ohlins are a 36mm X 260mm spring, where stock is 36mm X 270mm. Per Skip @ OrientExpress.com there are a lot of spring options for 36mm X 260mm, and not so much for 36mm X 270mm. Picked up the springs used but never used for $100 shipped from a local guy, they came out of an Ohlins 2006 GSXR1000 cartridge replacement kit (iirc), and you can find them on ebay in the same range or cheaper.

I've got the Traxxion Dynamics extenders installed ("Extended Showa Fork Cap for GSXR") that gives me +20mm to play with. I didn't document the installation of these but I'll prob do so when I tear into the forks over the next month or 2. Straight fwd to install once you understand what is going on.

So yesterday I ordered the K-Tech 20SSK-INT-SHO-15 ($469 w/free 2 day USPS priority shipping from OrientExpress dot com) that should ship out today/tomorrow and hit by the end of the week. Track day at Buttonwillow on Friday then out of town the next week on biz, so I won't be able to get the forks off again until the week of the 13th. But that's real tight since the AFM round 1 opener is the weekend of the 18th which leaves me zero room to f*ck something up as I am bound to do along the way. I might wait till the week of the 20th to tear into the cartridges... We'll see how it goes

Current suspension setup:
Front:
1.0kg/mm RT springs currently installed, 20mm extenders installed, 125mm oil height, forks dropped +5mm into the extenders making it +10mm from stock. Sag set to 25mm. Compression and rebound not set, will let Dave set them first thing in the am Friday

Measurement notes: Per service manual stock fork setup is 5mm showing from top of triple to cap seam. Fully extended fork length from cap seam to the top of the the edge where the slider meets the fork bottom is 618mm

403mm from the top of the bottom triple to the edge where the slider meets the fork bottom. Reading in the 'running wide' thread that people are seeing 428mm, length diff in diff years?

Rear:
stock shock with stock internals that's never been serviced with RT 11.6kg/mm spring. 318mm eye-to-eye (per the book, unmeasured) with 9mm of shims added to the top of the stem of the upper mount. Rider sag at 25mm. As with the forks, no rebound/compression set, will let Dave have at it.

Tires:
Pirelli Diablo Supercorsa. 180/55 SC2 (hard) rear @ 319.28 radius, 638 diameter, 2006 circum. 120/70 SC1 (medium) front @ 301.67 radius, 603 diameter, 1895 circum

Rake/Trail:
with 9mm shim in rear and forks height at .72 above top triple (as I bought it, no rhyme or reason):
23.721/99.913

Frame/swingarm:
measured as "very straight" by Gerry @ GP Frame and Wheel, can post worksheet later when I can post/link

Goal for this week: install the pair of 1.12 Ohlins springs and set the oil level at 125mm with Maxima 5wt, then hit Bwillow Friday for a track day and work with Dave Moss to get the springs working correctly and confirm geometry. Re-evaluate next steps afterwards.

--------------------

Couple of reference links to on-topic resources I've found (ugh, can't post links yet, will save them and update later when I can):

@mikeinbiken 's "k tech fork internals installed" thread was the motivation to start this project and go with the more expensive K-Tech

@rraiderr 's great "running wide" thread where @goodmatt78 and @Moto_Joe along with others provide a ton of setup info:

@SPL170db 's DIY fork cartridge holder photos shown in post #6 of the "fork tools" thread in the General Bike forum

In the "06-10 GSXR 600/750 fork Ohlins revalve dampening rod disassemble" YouTube video he shows how to get the valves out of the cartridges, but at the 3min mark (controversially) he cuts the mechanical bump stop out in order to get the rod out of the cartridge to get to the rebound valve, vs the Ohlins suggestion of drilling some hydraulic reliefs to prevent hydrolock while keeping mechanical lock intact. The comments section shows a link to a PDF of the Ohlins cartridge replacement instructions, but the link no longer works

Partzilla microfiche of the "Front Damper" cartridge

---------------

comments, suggestions, criticisms welcomed. I'm sure I'll have plenty of questions along the way along with many "learning opportunities" to recover from...
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Last edited by miked_187; 02-28-2017 at 02:02 PM. Reason: better grammar, mentions fixes, added tire info and rake/trail
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post #2 of 11 (permalink) Old 04-18-2017, 10:05 PM Thread Starter
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Re: K-Tech 20SSK-INT-SHO-15 Fork Piston Kit Installation in K9 750

The day at Bwillow did not go well at all, the bike came home and has been sitting in favor of other racebikes. I wasn't in the mood to be chasing suspension for the rest of the year when I came home, was ready to sell it so I decided to let it sit in the corner for awhile so I didn't do anything stupid.

Net result at the end of the track day was that we couldn't get any heat into the front tire. The front was never above 100* on the pyrometer measured just off the track exit before the pits. Rear was measuring consistently in the mid 130*'s which is where I like to run them. We raised and lowered the front throughout the day trying different things without luck, changed front tire air pressures, and rebound and preload. No change to the vague feeling in the front.

So I rode Laguna with a buddy a few weeks later, he had an '06 600 that he loaned me that I absolutely loved, was why I bought the 750. His 600 was dead planted to the ground at Sears Point, not a twitch all day out of it and I rode it hard. Hadn't seen him all winter and he asked how the 750 was coming along, told him it was parked, no progress at all even after working all day with Dave, that I didn't have time/desire for dealing with it. I was riding my R1 for awhile to get my confidence back. He said he'd actually lowered the rear of his 600 to get it to handle like that, and offered me his Penske shock with adjustable ride height to play with to help get the 750 sorted. I finally got the shock in my hands over the Easter weekend.

So I measure his shock - 322 eye to eye with the adjuster all the way in to make the shock as short as possible. I have a spare stock 09 750 shock that I grab and measure - 315mm eye to eye. I had 9mm of shims which puts me at 324.

Dave suggested going from the 180 to a 190 in the rear, and to move the rear axle back onto the back half of the adjustment range, wheel base is too short right now.

Current plan is to grab some thin shims, use my shock and shoot for the 320-322 range in the rear, and forks +5 above the cap seam which is +10mm over stock, moving the axle but keeping the 180's on it for now. I don't want to throw any more money at this thing till it gets sorted out, got a pile of 180 takeoffs I can go through. The 1.12 front springs are too much, so I'll change one of them back to a 1.0 which leaves me at 1.06kg/mm. Not at all fun to ride, so vague up front, it's killing my confidence. I'll ride it Monday at Thunderhill with these changes and see if I can make some progress.

Last edited by miked_187; 04-18-2017 at 10:09 PM.
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post #3 of 11 (permalink) Old 04-19-2017, 05:01 AM
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Re: K-Tech 20SSK-INT-SHO-15 Fork Piston Kit Installation in K9 750

This is a great thread, tons of fantastic info here!!! Thanks for sharing, keep it going!



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post #4 of 11 (permalink) Old 04-20-2017, 01:57 PM Thread Starter
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Re: K-Tech 20SSK-INT-SHO-15 Fork Piston Kit Installation in K9 750

started in on the shock rebuild using RaceTech parts, find the thread here:

https://www.gixxer.com/forums/137-08-...internals.html
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post #5 of 11 (permalink) Old 04-21-2017, 08:27 PM
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Re: K-Tech 20SSK-INT-SHO-15 Fork Piston Kit Installation in K9 750

I've been following your thread with some interest as I recently purchased a 2013 750 as a track bike although I predominantly ride at Willow and Chuckwalla. I was experiencing the same problems at Chuckwalla and was unable to get the front hotter than 125 versus 165 in the rear. After messing around with the settings over the course of 2 days I found the front fork over preloaded. After reducing it to 31mm of sag and opening up the comp and rebound to factory settings I'm able to up the temp to 150. The fork is now working mostly in the middle third of its stroke according to my zip tie and the front end has much more mechanical "feel." I suspect that more fork movement somehow corrolates to allowing the bike to maintain a more desireable swing arm angle (~12.5 degrees).

As a reference, i weigh 170 w/o gear, stock front forks and a penske set at the lowest height (+10 mm over stock length). The bike did 1.28's at Willow with 4 day old R10's.

Hope some of this info can help.

Peter
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post #6 of 11 (permalink) Old 04-21-2017, 08:42 PM Thread Starter
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Re: K-Tech 20SSK-INT-SHO-15 Fork Piston Kit Installation in K9 750

Thanks for chiming in Peter, I'd kill to get the front at 125*. I have a rear that looks like its been through a lite track day, and a front that looks like its done 1/2 a session on the bike right now after both tires were on for a full day at Bwillow.

I *loved* the R10's, just couldn't get Bridgestone to come out to track days so I had to switch up so that I could run the same tires all the time, I like the Pirellis, but I'd love to go back to bstone. Anything but Dunlops

I'm waiting for tools to come in to let me finish up the shock so I'm off the 750 for a week or 2, but doing lots of track days this year so the 750 will make it out on the track "real soon now". Appreciate you posting numbers, big Willow is on my list to make it back to this summer after many many years away
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post #7 of 11 (permalink) Old 04-21-2017, 08:54 PM
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Re: K-Tech 20SSK-INT-SHO-15 Fork Piston Kit Installation in K9 750

Let me know when you're planning on Willow, I'm always looking for guys to ride with. We are going out again in june with Trackxperience and Chuckwalla on may 5th with trackdaz.

On a side note, I've noticed that the recommended spring rates that Racetech publishes tend to be on the stiffer side and this 750 seems to like softer springs. I usually use a 1.0 or 1.05 front spring but the stock gsxr works pretty well so far. Heck, even penske recommended a 525lb rear spring which is a lot softer than normal for me.
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post #8 of 11 (permalink) Old 05-11-2017, 09:02 PM Thread Starter
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Re: K-Tech 20SSK-INT-SHO-15 Fork Piston Kit Installation in K9 750

So I started all this with 9mm of shims between the frames shock mount and the shock clevis. I pulled out 3mm and at the same time I set the front forks down in the triple clamp 2mm and took the bike to Thunderhill East a few weeks ago. No spring change to the 1.0 at that point, still 1.12 on both sides. Installed a new 520 chain, couldn't get the rear axle back as far as I wanted, the one link took the axle past the rear adjustment, if I took one less link then the axle was just at the middle. Hoping as I get some chain wear I can get the axle back another few mm's. Off to the track we went.

I was really pleased to see that I finally got some heat in the tire and finally a bit of front feedback going, 119-126* throughout the day. Was jazzed. Nowhere near great, but positive progress. Had to head out early that day so I didn't have a chance to play more with it. Wear pattern on the front tire is pretty far up, a big chicken strip, but I'm taking the rear right to the edge of the tire. Weird

I'm in the garage now doing the spring swap on 1 fork to the RT 1.0 spring, and setting the oil height at 125mm (vs stock 115mm air gap) to get a bit more damping. After I got home a few weeks back I pulled another 3mm shim out, so now I'm sitting at one 3mm shim on top of the shock clevis and forks still 2mm down the hole.

Trying to get to Thill West on this Saturday to shake it out further, but it's been a wild week and I'm behind. I plan on continuing to track front tire temps till around 11a, then try to take the final shim out on the clevis and see what happens. Part 2 is to drop the fork caps flush with the top triple while all the shims are out. Then see what I learn from all this. If I have time I might even take the forks back to stock just to see how it works.

I wish I had some thinner shock clevis shims, does anybody have a source for 1mm shock shims so that I can continue to fine tune the bike?

Thill West is tight and twisty so I'll have a lot of time on the front tire and should learn a lot.... if I actually make it.

Last edited by miked_187; 05-11-2017 at 09:56 PM. Reason: numbers were incorrect, fixed
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post #9 of 11 (permalink) Old 09-07-2017, 08:17 PM
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Re: K-Tech 20SSK-INT-SHO-15 Fork Piston Kit Installation in K9 750

Great info! I will be doing full front and rear Ohlins myself on my K9 750 and hope to give feedback! Thanks for the good details here!
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post #10 of 11 (permalink) Old 09-07-2017, 11:20 PM
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Re: K-Tech 20SSK-INT-SHO-15 Fork Piston Kit Installation in K9 750

Keep us in the loop as I have a 2016 GSXR 750 and also being 6'2 and 245 set up is important

Just a side note I find the 180/60 Pirelli SuperCorsa SC or Superbike Slick to work great as our set-ups are quite similar.
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post #11 of 11 (permalink) Old 07-11-2019, 11:07 PM
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Re: K-Tech 20SSK-INT-SHO-15 Fork Piston Kit Installation in K9 750

Well?....
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