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Discussion Starter #1 (Edited)

So I had OEM forks & shock rebuilt with K-Tech springs to my weight, and I just got them installed. I have yet to tune them or even set sag, and I know I need more preload in the front as I've bottomed them out twice while braking over a bump in the middle of the same corner entrance. I'll be coming in on the brakes, and as soon as I hit this bump, I felt the incredibly unsettling thud of the already loaded forks bottoming out while absorbing said bump.

My question is this: Is this damaging the forks? Does bottoming out your fork damage them?
 

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Formerly CLCRACINGAaron
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There is a bump stop at the very limit of fork's travel to prevent damage so don't be too concerned at the moment.

The preload is important to set for the rider sag but don't forget the compression damping. The idea is to control the upward stroke of the fork to keep it from maxing out. The first thing you should do is set the preload to your weight, then set the clickers to the factory settings. Then see how it reacts.
 

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What is the Preload set at?

What is the Rebound set at?

What is the Compression set at?

What is the oil level set at?

What weight oil did they use? (Brand / Weight)

What weight spring did they install vs the OEM? Why did you think you needed to change the springs?

What did you set the sag at?

I wouldn't worried about hurting the forks, I'd be worried about crashing!
 

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2016 Kawasaki ZX-10R KRT ABS Edition
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This is a really good video to watch to get the basics on sag, compression, and rebound damping. Setting the sag can be tedious so I skipped that personally. I used video 2 to at least get a good baseline before having some trackside suspension guys work their magic. When those guys got the sag right though WOW... night and day difference and now the bike, as heavy and long wheelbased as she is, just throws itself into turns and induces lean angle.


 

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If you weren't having a problem before you sent them in and now you are having a problem check to see what the different is. Dunno what the process is for RT but at our shop we give you the suspension back with the same settings you gave them to us at. The damping may not be set.

Also RT doesnt have springs that are bike specific. They use washers to take up the slack if needed. We've seen those spacers shift in the tubes and cause false bottoming. Not much the internet can do, so go out and see what the suspension is set at.
 

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Discussion Starter #6
>> Multiple Reply <<

NEON <> Thank you. I dialed in two more rotations of fork preload & 2 clicks of compression damping. It's improved my street feedback, but as I'll explain below, it's still off.

EVALL <> Long time no talk. If you equate “weren’t having a problem [before they were rebuilt]” to not bottoming out the forks, they were not… before. They were OEM springs that required massive preload on the rear spring & max preload on the forks. I definitely buried the forks on the street & track, as was, as the zip tie always bottomed out, but I never experienced a hard bottoming out like this. I mean this experience was a "THUD". Before, all my settings (compression/rebound/preload) were pretty much maxed out as I’m 250#, but I was experiencing comfortable results on my first & only track day (when I was 270#). Tire wear at Homestead-Miami Speedway was really good, but overall suspension performance was definitely “tired”. I know from the previous owner that the oil/fluid/springs were 2004 OEM. I was able to set rear sag before HMS @38mm (if my memory serves me correctly), and I maxed the fork preload w/o measuring sag as I knew I needed all OEM could offer.

As for the base settings from the mechanic whom rebuilt the suspension, I know he set the shock preload @10mm & the forks @8mm at their minimum preload settings. Where he set the compression/rebound I really don’t know as I have yet to back everything out or turn everything in to see where it is. I, originally, sent him the hardware via mail, and he mailed everything back for me to have installed locally which, 9 months later, I was just able to afford… thus the impetus to this thread.

I just edited the OP as I gaffed by stating they were RaceTech springs; in fact, they were K-Tech, and specifically, the shock spring is a 105nm. I also know he worked on the shock piston for stronger valving to control the stronger spring. Furthermore, he told me he, “modified the bottom out cups so as to use the full stroke of the fork”.

DDIPAUL <> Been awhile! Nice to talk with you again, and thank you for the video referral. I’ve been an online student of Dave Moss since I bought this Gen 1, about 2 years ago, and my only pause in personally adjusting my preload has been my not having two gear-head friends that can help me in concert. As far as I’ve learned, setting preload requires 2 extra set of hands unless I can afford laser measuring equipment… which I can’t.. yet. I know of a local wrench that tunes suspension, but I just can’t afford him, yet.

BOTTOMS-UP <> I’m mildly confused by your line of questioning as you know your questions can not be currently answered, as I explained in the OP, “I have yet to tune them [forks/shock] or even set sag”.

I’ll gladly add, the [fork] oil level is set @130mm with Motul fluid (weight unknown). The wrench (Steven Breckenridge of Fluidolgy Inc.) is a well respected tuner that I am entirely comfortable entrusting my life to, and I trust his judgement within his craft.

As for crashing, sorry to disappoint, but I have kept the rubber side down, thus far. I have yet been able to generate enough capital to make it to my next track day, but on the street, I have definitely experienced enough over the last 4-6 weeks to know, w/o question, that my shock/fork:rebound/compression balance is off… way off. I have experienced a lot of front to back movement, almost "po-go"-esque in bumpy exits. My F-150, my typical transportation, is currently out of commission which has left me with my Gen-1 as my sole mode of transportation… rain & shine (S. FL). This last 5 weeks has taught me a lot, and one of which is as explained above. IMH[umble]O, I push my bike… on the street. Yes, I know it’s only the street, but I, embarrassingly & apologetically, do not obey street laws. ‘I can not drive 55’, and I push the bike on the street, against my common sense, as it’s my only outlet. My current existence, at least the last 51 weeks, leaves my ride to work & back to home as my only R&R. Intrastate/interstate highway entrance/exit ramps are my only outlet… so I employ them.
 

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Hi man ! Stock oil level is 91 mm .
What spring rate have the new springs ? I still run the stock 1 kg/mm2 but on the track seems to be little soft (I am ~72kg) .
Forget for the sag . When you push you need less than 30% sag .
 

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Uhhh, did they need to be shimmed out with the rebuild? I had to add some shims to my last spring swap because it wasn't at the proper operating spec even though I was at the manufacturers spec.
 

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Stock oil level in the gen 5 service manual is 160mm w 5wt oil.
91mm would be brutal,

BTW - the stock spring is .115, which is super stiff for OEM. I think that you said Ktech assigned .105’s? Without asking your weight -
Where are you bottoming? Super hard braking at the end of a long straight at the track vs more moderate situation may make a difference in solutions. Sorry if I’m captain obvious - it looks like you already have a lot of knowledge and experience on the topic.
 

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The Pace
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Don't touch anything on this bike until is simply fails. Read that about 1000 times or until is sinks into your unconscious.

I ride the crappiest roads. Same two loops all the time; for years. I know every stupid crappy dip and bump. Even WITH LEAKING SEALS on the '11 10r the forks NEVER failed, not MATTER WHAT I DID.

Year after year after fooking year I constantly see the exact nonsense from those that simply can't ride but blame a bike that can kick ass with a stupid OEM dorky can with a dork fender at any track given a rider that the bike loves.



lol!
 

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2018 ZX10R SE
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Stock oil level in the gen 5 service manual is 160mm w 5wt oil.
91mm would be brutal,

BTW - the stock spring is .115, which is super stiff for OEM. I think that you said Ktech assigned .105’s? Without asking your weight -
Where are you bottoming? Super hard braking at the end of a long straight at the track vs more moderate situation may make a difference in solutions. Sorry if I’m captain obvious - it looks like you already have a lot of knowledge and experience on the topic.
except he is on a gen 1, the gen 5 has a much heavier spring in it than the other gens. also, if the dude said he modified the bump stop to use the full stroke sounds like he kinda sorta removed it. not really ideal. best option, lose some weight
 
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