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Stock fork travelling and offset end

9K views 26 replies 5 participants last post by  kwaka10r 
#1 ·
I am looking basically for the offset but other measure will be appreciated too.About the offset I heard on most Gsxr is about 30mm to bottom end.
 
#4 · (Edited)
maybe I didn't explain it well.

I want to know how much distance left when the fork reach its internal limit when compressing, and how long is that measure, I mean, "the gold coloured visible part left of the fork leg" when fully physically compressed and bottom out. I am looking for that measure.
 
#7 · (Edited)
if you have a zipper on your fork leg you can adjust the fork travelling better, let alone SAG measures are calculated over a specific value, let's say, between 20 and 30% of total travelling with the rider.
If you have a % of the fork leg that will never be compressed, you should't take that amount in consideration, because it's not part of the real fork travelling.
I guess most of the standard bikes have internal stops you can remove in any decent suspension tuner to gain some travelling and more agressive geometries, for example, when braking and turning on track.
 
#6 ·
I thought that this was asked some time ago (not sure for what year) but couldn't find it. The most I can offer is that the stroke is listed in the service manual as 120 mm (believe that the 4.92" is a typo that should be 4.72"). If you know the fully extended distance, you can use that to calculate fully compressed.
 
#8 ·
Ok, I understand your logic. BillV gave you an idea without pulling your forks apart. Keep in mind, there are top out springs and I am not sure if the extra extension from them is calculated in the travel. Also there are hydraulic bottom outs, and I am not sure in real life if the fork ever uses up all the hydraulic lock-up travel on the bottom out and hits mechanical stop.

I wouldn't remove the hydraulic stop. I would maybe reduce its range making it progressive by drilling a hole in the side of the cup.

The K1/2 geometry can be improved a little by lifting the rear with a 3-5mm spacer on the shock mount. The front IMO doesn't need to be lifted. Stock height is fine or possibly a little lower.

Less triple offset (more trail) seems to improve the handling. Stock is 32mm. 28mm works well in my experience.
 
#9 ·
I have Ohlins linear springs too, I don't know If that changes something about the stock measures.

In the past years I have been really interested in geometry & suspension tuning matters, experiencing myself and watching a lot of videos from tuners and "gurus".

What I have noticed is that, since my last fork revision (ohlins springs and ohlins oil), I have all my fork setting almost to the minimum.
Just 1 line left on preload, extension fully closed, and compression almost fully open. I am like 115kg (253 lbs) with all rider equipment and I can't even make bottom out on street, and the fork has pretty sporty reactions "by hand" (typical Dave Moss bouncing method). I will say it's near a really good set up, but I don't know what to think about having those parameters tweaked near to its minimum limits.

I am thinking of the oil being too "hard", because the spring is supposed to be matching riders on my weight.

the bike feels good but I don't know if I can improve it more...
 
#10 ·
What spring rate are you running? I'm about the same weight as you and, after switching to 1Kg/mm springs, I still need to crank the preload all the way in to get front sag below 40mm. If I remember correctly my rebound damping is also almost fully in, and my compression damping is about a turn out from fully in, or something like that, mostly to combat brake dive.

In the end though, the purpose of preload, is to allow you to set the resting (or coasting) position of the suspension, dividing the total travel into travel available for compression and travel available for extension. If you don't feel any jolts due to bottoming or topping out, (unless you hit the mother of all potholes of course), then I don't think there's much point in worrying about it (although, if you've got a lot of headroom, i.e. the zip-tie never comes close to covering the full 120mm of travel, you might consider softer springs next time around).

You can then set geometry, either by making small adjustments to sag, or, more properly, by pulling/pushing the forks through the triple clamps and shimming the rear shock, as suggested. That's a compromise too, of course: straight line stability vs. easier turn-in (and more feel for available traction, I believe, as less mechanical trail makes the effects of the tire's pneumatic trail more prominent, and the latter peaks out a bit before the side-force peaks out and the tire starts slipping, thus providing a sort of early warning). In general, I think, it's best to have an idea of what you want to improve, before attempting adjustments.
 
#12 ·
I have same spring rate than you. I think my last sag was 38mm and the 3rd line showing up but the zipper doesn't seemed to go low enough. So I decided to go for the 4th line out of preload, and 3 clicks of compression out. Now it seems going lower but I have to test it on route.
 
#11 ·
Fork oil should be 5W. I'd go with Ohlins oil. Can't remember which 5W is superior, 1311 or 1305. Think it may be the 11.

Comparing the oil heights to Ohlins fork recommendation, Suzuki seem to run it very high. This results in less air volume and more air spring for travel or progressive air springing. I'm going to try running lower oil levels next oil change.

As dpapavas mentioned, what are your spring rates?

For your weight front should be about 1.1kg/mm and rear 9.0kg/mm.

If you can't get enough sag from the front you need to shorten the spring spacers unless your springs are too hard, which would result in not enough unloaded to loaded sag difference.
 
#16 ·
Great info being posted in this thread...

:punk

While I don't know a lot of the more technical aspects of the suspension components, I know how they work in the real world and under racing conditions.

You never want the fork to bottom out, even under the most extreme braking situations. When I would go into T1 at NJMP, with the back of the bike skipping around and basically riding on the front wheel, my zip tie would still leave about 5mm of unused fork.

I did have an issue with the fluid (or lack thereof) and it was making my forks bottom out. We remedied that by adding fork oil, keeping the same weight, which was Öhlins 5W. Unfortunately when I sold my bike I gave the new owner all my notes, so I don't remember what my fork oil level was, but I am pretty sure it was 160mm with the Öhlins 30mm cartridge kit installed. I think on the K1-K2 1000's, you want 170mm of fork oil. If you are still bottoming out, running the correct springs for your weight, you can add 10mm of fork oil at a time until it stops.

Not sure if any of that helps...
 
#17 · (Edited)
Yes, good info adding up here.

Good to know the lower oil height was working for you AntD.

Suzuki seem to go for a one size fits all. They use progressive setups to help cover a wider range of rider weights.

As you mentioned and as I have seen with many of the oil height charts for similar Ohlins forks they run much less oil height. I believe that is what contributes to the OEM setup becoming too firm a ride over very bump surfaces. The air spring ramping up its rate.

Ohlins recommend 140mm for their FGRT GSX-R1000 fork. Stock oil level is 90mm which is way to small IMO. Such a short oil level will result in huge ramp up of the spring rate.

Attached is a chart for a ZX-6R 25mm kit according to the website I lifted it from.

 

Attachments

#22 ·
The shock it's supposed to match the original measures of k1 to k4 straight from Bitubo factory.
If you noticed the"empty" upper zone, it just looks that way. You can see where the preload zone starts 4 rings down the body, and its just a bit preloaded
 
#24 · (Edited)
Maybe. Bike handles good. Rear traction and tire wear on track are good too. When I bought the bike from the previous owner, reading the owners manual, I discovered that forks should be set 7 millimeters above the upper clamp, and mine was like double. I asked the previous owner and he said that he didn't touch that and its a bit weird because in these years watching pictures from many k1-k2 I can see some bikes with my previous setting and some with the 7mm setting. And I am talikg About apparently normal riders with stock bikes. Not hardcore or lowriders, draggers or stuff like that
 
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