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herrmann450r

My take on the KYB RE forks

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Glen, I am using this spring perch... 

https://www.technical-touch.com/kyb/front-fork-all/category-description=spring-collar-complete/spring-collar-complete-28mm-factory-aluminium-160190000101?returnurl=%2fkyb%2ffront-fork-all%2fcategory-description%3dspring-collar-complete%2f

It has smaller holes (so it helps towards bottoming) but also its cylindrical part is longer. Initially I used them for a couple of bikes I had to lower, they were good for about 23-24 mm (but not more). 

Beta KYB (and I believe Sherco and GG) perches are the plastic ones so not possible to cut. They do have a 2nd ring groove higher up though. 

Blue bike? Since you mentioned bigger cartridges, probably a Yamaha (mv/reb face shim 21mm)? Edit : just saw it, YZ-FX. 

Edited by dirtbird

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1 hour ago, dirtbird said:

Glen, I am using this spring perch... 

https://www.technical-touch.com/kyb/front-fork-all/category-description=spring-collar-complete/spring-collar-complete-28mm-factory-aluminium-160190000101?returnurl=%2fkyb%2ffront-fork-all%2fcategory-description%3dspring-collar-complete%2f

It has smaller holes (so it helps towards bottoming) but also its cylindrical part is longer. Initially I used them for a couple of bikes I had to lower, they were good for about 23-24 mm (but not more). 

Beta KYB (and I believe Sherco and GG) perches are the plastic ones so not possible to cut. They do have a 2nd ring groove higher up though. 

Blue bike? Since you mentioned bigger cartridges, probably a Yamaha (mv/reb face shim 21mm)? Edit : just saw it, YZ-FX. 

Probably have the free pistons with raised plastic shoulders instead of bushings too, like Italian Husky KYBs. 

Yes, 2020 Yamaha YZ250FX.  Just started setting it up, no rides yet except around the street a bit.  250Fs have come a long way!

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1 hour ago, GP said:

Probably have the free pistons with raised plastic shoulders instead of bushings too, like Italian Husky KYBs. 

Yes, 2020 Yamaha YZ250FX.  Just started setting it up, no rides yet except around the street a bit.  250Fs have come a long way!

I'm pretty sure all kyb tc came with plastic after 2014. No?

 

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Well, the Tech Touch catalog shows, for YZ250F, 2012 - 2018 the same part, but different than the GG and Sherco.  Also shows the 2012 Husky TXC to have the same part as my 2011 YZ250F forks and I know that is wrong at least in my case, the TXC being plastic.  So, with inaccuracies, not sure what's up.   My 2020 is bigger dia. so I'll find out when I tear it down.   Probably leave preload alone being its a 4stroke.  Buy holy crap does it feel stiff off the floor.  Break in ride gonna be brutal!

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2 minutes ago, GP said:

Well, the Tech Touch catalog shows, for YZ250F, 2012 - 2018 the same part, but different than the GG and Sherco.  Also shows the 2012 Husky TXC to have the same part as my 2011 YZ250F forks and I know that is wrong at least in my case, the TXC being plastic.  So, with inaccuracies, not sure what's up.   My 2020 is bigger dia. so I'll find out when I tear it down.   Probably leave preload alone being its a 4stroke.  Buy holy crap does it feel stiff off the floor.  Break in ride gonna be brutal!

Interesting both sets of my TXC forks are not plastic.

 

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3 minutes ago, hammer41 said:

Interesting both sets of my TXC forks are not plastic.

 

That's what I mean, inconsistencies.  My brother's was a late '12 and plastic perches for sure along with the no-bushing free pistons.

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14 hours ago, GP said:

Don't change ICS springs, they are for oil stabilization.  Do you let N2 out of your shock to tune it?  My brother had a big name tuner make a total mess out of a set of KYBs with softer ICS.  I have a great Beta/KYB setup for NJ / PA rocks.  From what I can tell by brief comparison these new bikes have a bit too much preload.   From experience, drop preload,  4.5-4.6 spring, single stage base,  light bleed stack, .38 - .4mm float.   Amsoil Shock Therapy Lite.  

Lighter ICS will hurt oil stabilization especially with fast riders. For average rider how would you set-up without changing the ICS to get small bump compliance,,, plushness in the first part of stroke??  From my experience you can't get slow speed plushness with ICS rates over 1.7kg without the valving blowing thru the stroke at speeds.

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2 hours ago, GP said:

Probably have the free pistons with raised plastic shoulders instead of bushings too, like Italian Husky KYBs. 

Yes, 2020 Yamaha YZ250FX.  Just started setting it up, no rides yet except around the street a bit.  250Fs have come a long way!

They came with those.. 

IMG_20200124_160303.jpg

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55 minutes ago, dirtbird said:

They came with those.. 

IMG_20200124_160303.jpg

Yeah,  they replace the Teflon bushings with the molded in shoulders.  Seems to work fine.  You don't need upper oring with drilled piston.

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18 minutes ago, GP said:

Yeah,  they replace the Teflon bushings with the molded in shoulders.  Seems to work fine.  You don't need upper oring with drilled piston.

I haven't touched a thing. This is how they came from the factory with this hole and both orings. 

I just replaced them with the aluminum ones I already had. 

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1 hour ago, weantright said:

Lighter ICS will hurt oil stabilization especially with fast riders. For average rider how would you set-up without changing the ICS to get small bump compliance,,, plushness in the first part of stroke??  From my experience you can't get slow speed plushness with ICS rates over 1.7kg without the valving blowing thru the stroke at speeds.

I assure you its possible, I've done it.  I can crawl through a boulder filled creek and still run 3rd gear over embedded rocks with confidence.  I run 2.0Kg ICS that are shimmed for even more preload so pressurization starts when damper travel starts (just like the aftermarket alloy pistons).  If you do the math, the ICS contributes very little to overall total spring rate.  If you need less initial spring then change your main spring/preload not your ICS.  Your midvalve float dominates the initial feel of the fork in the rocks, its the coarse adjustment.  I run a moderate single stage base, and a light bleed stack, not sloppy by any means.  I think the ICS swap is done because people don't take the time to figure out the balance of the mid and base.  I've played with lighter ICS a few years ago and went back to stock pretty quick.  Also,  if your cavitating from too light an ICS, this can cause a rebound problem that may feel like a compression problem to the casual tester.  The old Zoke 48 PFP fork ran high cartridge pressures, and high ICS preload, and was still able to be set up very nice.  Use video for evaluation, it doesn't lie or misinterpret effects.

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1 minute ago, dirtbird said:

I haven't touched a thing. This is how they came from the factory with this hole and both orings. 

I just replaced them with the aluminum ones I already had. 

I think I read somewhere they drill them at the factory now that the Showa patent for the true dual chamber expired.  The solid piston and third chamber (above piston) was a way around that patent.

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8 minutes ago, GP said:

I assure you its possible, I've done it.  I can crawl through a boulder filled creek and still run 3rd gear over embedded rocks with confidence.  I run 2.0Kg ICS that are shimmed for even more preload so pressurization starts when damper travel starts (just like the aftermarket alloy pistons).  If you do the math, the ICS contributes very little to overall total spring rate.  If you need less initial spring then change your main spring/preload not your ICS.  Your midvalve float dominates the initial feel of the fork in the rocks, its the coarse adjustment.  I run a moderate single stage base, and a light bleed stack, not sloppy by any means.  I think the ICS swap is done because people don't take the time to figure out the balance of the mid and base.  I've played with lighter ICS a few years ago and went back to stock pretty quick.  Also,  if your cavitating from too light an ICS, this can cause a rebound problem that may feel like a compression problem to the casual tester.  The old Zoke 48 PFP fork ran high cartridge pressures, and high ICS preload, and was still able to be set up very nice.  Use video for evaluation, it doesn't lie or misinterpret effects.

Do you add a stack in the low speed bleed? 

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Just now, dirtbird said:

Do you add a stack in the low speed bleed? 

Well being I started with YZF forks that had a stout bleed stack I softened it up, 1 or 2 20mm face shims.  On the 4stroke I will leave it stiffer. 

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7 hours ago, GP said:

Probably have the free pistons with raised plastic shoulders instead of bushings too, like Italian Husky KYBs. 

Yes, 2020 Yamaha YZ250FX.  Just started setting it up, no rides yet except around the street a bit.  250Fs have come a long way!

Mine are apart now.

The piston is very similar to the latest KYB shock piston. All metal.

Beta vs KYB shock piston pic for comparison

 

 

thumbnail_20200211_065825.jpg

Edited by KRAYNIAL
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11 hours ago, GP said:

Yes I measure everything apart and for preload I cut the spring perches.  You can't go crazy with this though as you need the L/D to keep the perch from rocking on the cartridge.  A few mm has been fine, I shortened mine 4mm for 4mm preload.  If the cartridge has an alternative ring groove farther up, you can cut and split (carefully) the retainer,  move the ring up, replace with a removable retainer from JBI and shim as required.

These forks can be firm, controlled, and not abusive at the same time riding rocks all day at a good pace, and I'm no kid.   The myth that CC forks are just stiff and OC better for woods is bullshit by people that can't tune them or want to sell OC forks. 

Now, not sure what the new Beta KYB is like but my new blue bike has a larger cartridge and much different stiffer specs,  plus the leaf spring mid valve.  Gonna have to model that one as previous data does not apply. 

Did you buy a TM ? 

MM 

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17 hours ago, GP said:

I assure you its possible, I've done it.  I can crawl through a boulder filled creek and still run 3rd gear over embedded rocks with confidence.  I run 2.0Kg ICS that are shimmed for even more preload so pressurization starts when damper travel starts (just like the aftermarket alloy pistons).  If you do the math, the ICS contributes very little to overall total spring rate.  If you need less initial spring then change your main spring/preload not your ICS.  Your midvalve float dominates the initial feel of the fork in the rocks, its the coarse adjustment.  I run a moderate single stage base, and a light bleed stack, not sloppy by any means.  I think the ICS swap is done because people don't take the time to figure out the balance of the mid and base.  I've played with lighter ICS a few years ago and went back to stock pretty quick.  Also,  if your cavitating from too light an ICS, this can cause a rebound problem that may feel like a compression problem to the casual tester.  The old Zoke 48 PFP fork ran high cartridge pressures, and high ICS preload, and was still able to be set up very nice.  Use video for evaluation, it doesn't lie or misinterpret effects.

You engineer types have too much time!  I send mine out and they are awesome in the rocks. 1.1 ics spring and all!  I had them valved by a different tuner than usual and they came back too stiff for my rocky trails, simple change to 1.1 from 1.4 ICS made all the difference!  Cavitation Smavitation.....I'm too slow to notice I guess.

Edited by Primal Enduro

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21 minutes ago, MartyMOOSE said:

Did you buy a TM ? 

MM 

YZ250FX.   Can't wait to get it in the woods,  the motor is awesome  for a 250F.  The mapping app and dual selection is cool too.  

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1 hour ago, GP said:

YZ250FX.   Can't wait to get it in the woods,  the motor is awesome  for a 250F.  The mapping app and dual selection is cool too.  

Oh we are so different not my cup of tea my son races a lightly tuned WR250f not my idea of fun. Its a 15 though but I image the engine would be close. His pulls way better than the 19 we have ridden. They respond really well to a 14.2:1 piston or if you like doing rebuilds a 14.5:1 the later option gets about 90 hrs out of a rod in our case. 

MM 

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