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R1peacock

2019 YZ250FX Rear Shock Nitrogen

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Guys, sorry to bring up a question that has been beaten to death.....  Trying to look for clarification.

Im doing some work on my rear shock and a local suspension shop that can refill the nitrogen asked me about the pressure settings and what I preferred.  I’m looking for the recommended nitrogen pressure for the rear shock.  Plenty of talk on here and elsewhere with people saying stock is 142-145 and rebuilt is 165ish.  Where are these numbers coming from? I looked at my manual and don’t see specific numbers.  I have a pdf manual that I indexed and electronically searched for the term “nitrogen” and nothing came back talking about pressure recommendations.  Is the 142-145 industry standards or does someone actually have something from Yamaha.

RP

Edited by R1peacock

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Two local suspension shops have both told me its 175psi in a kyb rear shock

I have had this put in with no issue

Yamaha consider the shock unserviceable so dont give pressure for rebuild etc, they say to replace with new

Check the race tech site it might say on there as well

Edited by GuyGraham

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Check the specifications chapter of your YZ250FXJ Owner's Service Manual.

Shock gas pressure should be listed there with all of the other specs.

I've always preferred the standard pressure setting as adding more pressure simply seemed to jack the back of the bike up.

Edited by YZEtc
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1 hour ago, YZEtc said:

Check the specifications chapter of your YZ250FXJ Owner's Service Manual.

Shock gas pressure should be listed there with all of the other specs.

I've always preferred the standard pressure setting as adding more pressure simply seemed to jack the back of the bike up.

Thanks, My 2019 YZ250FXK manual (top picture) omitted that line item in the specifications - spring rates are also omitted in the new manual.  I have a 2016 YZ250FG manual (bottom picture) and the STD Gas Pressure is listed as 139.4 psi.

 

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Edited by R1peacock

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The '15 FX manual lists 139.5psi.  I have always put 145psi in my shocks after rebuild. 

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Maybe I'm naive but I thought this was the type of question my suspension tuner would know.  I am confused that its your tuner that is asking you the question.

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23 minutes ago, Honeybagder said:

Maybe I'm naive but I thought this was the type of question my suspension tuner would know.  I am confused that its your tuner that is asking you the question.

My shop asked me if I had a preferred pressure setting.  They recommended 145-165psi and said the preferred baseline numbers would be printed in my manual.  Thats how I noticed in the 2019 FX manual those items are omitted but in the 2016 manual the rear shock specifications are more detailed.

Edited by R1peacock

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4 hours ago, YZEtc said:

 

I've always preferred the standard pressure setting as adding more pressure simply seemed to jack the back of the bike up.

👌

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Skip the nitrogen, use a quality high pressure bicycle pump or one of those ktm fork pumps. The difference is negligible and you can tailor the psi to your liking. 

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10 hours ago, swtwtwtw said:

Skip the nitrogen, use a quality high pressure bicycle pump or one of those ktm fork pumps. The difference is negligible and you can tailor the psi to your liking. 

Not good idea

You need a no loss valve setup else you loose a load of pressure when pulling off the pump and the you have no idea what pressure is,  in the bladder

Nitrogen is used because it expands less then hot and also will be dry, which air is not

Edited by GuyGraham
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14 hours ago, swtwtwtw said:

Skip the nitrogen, use a quality high pressure bicycle pump or one of those ktm fork pumps. The difference is negligible and you can tailor the psi to your liking. 

Super huge thumbs down.

  • Haha 1

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2 minutes ago, Honeybagder said:

Super huge thumbs down.

But he slept in the parking lot of a Holiday Inn Express last night.   :lol:

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For recreational use, I've been using air in both my YZ125 and CRF250X shocks for the past 3 years.

Yes I'm all for doing everything 'by the book' but I often experiment with revalves 

and don't want to invest in a home nitrogen setup just yet.

 

Using a 0-300psi MTB air pump with a no-loss type connector, 

in a low humidity environment I pump them up to 140psi. (both my bikes spec. 142psi)

After multiple checks the loss is actually about 2psi each time you disconnect the pump.

 

On a typical 75°F sunny day, after riding for 30 minutes (MX track) I've monitored the pressure increase a few times and at most it gained 5-10psi.

 

IMO the average recreational rider would be hard pressed to notice such a change,

but for racing purposes, no doubt the nitrogen would be preferred.

 

 

Edited by mlatour
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On 1/21/2019 at 4:29 PM, R1peacock said:

I have a pdf manual that I indexed and electronically searched 

You wouldn't like to share this manual with us would you?

Please. 

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On ‎1‎/‎22‎/‎2019 at 9:25 PM, swtwtwtw said:

Skip the nitrogen, use a quality high pressure bicycle pump or one of those ktm fork pumps. The difference is negligible and you can tailor the psi to your liking. 

No thanks !

Been doing them for years and I will stick with using nitrogen !

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I use nitrogen for the initial charge, then a suspension pump to fine tune depending on ambient temperature and terrain. The big reason for using nitrogen is it's dehydrated, moisture in air is what can cause inconsistentes in the pressure curves. With that said, most people on this forum wouldn't know any difference if the bladder was 100% or 78% nitrogen.

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2 hours ago, Timo2824 said:

I use nitrogen for the initial charge, then a suspension pump to fine tune depending on ambient temperature and terrain. The big reason for using nitrogen is it's dehydrated, moisture in air is what can cause inconsistentes in the pressure curves. With that said, most people on this forum wouldn't know any difference if the bladder was 100% or 78% nitrogen.

Most people on this forum don't know their a$$ from their elbow.   :smirk:

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There's a number of us here that use just air, with no issues.

Any of you nitro only guys have any actual experience of these problems, or actual proof (dyno sheets etc)?

Or are we just recycling others stories again?

 

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32 minutes ago, DEATH_INC. said:

There's a number of us here that use just air, with no issues.

Any of you nitro only guys have any actual experience of these problems, or actual proof (dyno sheets etc)?

Or are we just recycling others stories again?

 

:facepalm:    YOU'RE just recycling others stories.  Any proof or dyno sheets ?  The burden of proof is on the non conformist.  

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