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J_T

nitrogen charging

28 posts in this topic

hey all, long time, no post.

i'm interested in using bruce's directions for the shock rebuild but i want to make sure i can recharge it. can dealers recharge. and how pricy is it?

and can one buy an assortment pack of shims for forks and shock? where is best?

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It costs $15 at the Honda Dealer in Redlands. It's kinda hard to talk some dealers into charging past 180psi. Baja Designs , Precision Concepts, Race Tech , and others that do suspensions all pressurize to 220~240psi. That is what I fill the nitrogen here to. I buy my shims from RaceTech but, that doen't mean there the best just the closest :cry:

XR650R

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Bruce,

I understand that you do suspension work as well, is this correct? I bought ThumpDaddy's BRP and weigh a 240# and am 6.3. Would you recommend suspension work? I don't ride like you do at all, but intermediate trail riding and Dual Sport.

Thanks,

Rick

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I didn't put the spring on.......Make sure the race sag is set at 3.75"!

I think that spring is a Eibach 10kg? which is what I use on my bike. It's for a 200~220 pound rider. You have a real nice shim stack for your weight. 220psi nitrogen. The setup (if you have a Eibach 10kg spring) is what I use for most of these (click here)

VIDEO

(the old videos were done with a stock setup) I weighed 195pounds. If you don't hit bottom (your forks are setup real nice also) I would try Forks; 10~12 out on the compression (found at the bottom of the forks) 8~10 out on the rebound (top center) Shock; 14~16 compression (top on nitrogen tank)and 14 rebound at the bottom of shock where is mounts to linkage; chain side) what you have is way better then stock for your weight! :cry: but, if you start jumping or bottoming out; you will need more spring....but, for the way you are riding you have a awesome nice setup.

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Wow, 220 to 240 PSI :cry:

I only put 140 to 160 PSI in my rear shocks whether its an XR250, XR650, or the Bilsteins on my truck, etc. I never did agree with the info Race Tech suggested, but I'm shocked (pun intended :cry:) to hear that so many name brand shops use such a high pressure.

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Ask what Barnum puts in his :cry: You might have more in yours then you think if you haven't changed it. I asked him and I am sure it was right up there with the others.

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my Ohlins has 180psi as per the west coast Ohlins dude suggestion.

for sure everyone should consider getting their shocks 'topped up' with gas once a season.

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The seal in the shock uses the pressure to seal the oil from leaking......so, if youe real low to no pressure and a worn seal you can start leaking oil or sucking air. :cry:

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Ask what Barnum puts in his You might have more in yours then you think if you haven't changed it.

I actually charge my own shocks for our bikes, trucks and other toys, but I'll have to ask Barnum tomorrow since I need to inquire about some more parts I have on order with them, but I was under the impression after talking to various shock gurus testing their prototype shocks with shock dynos that nitrogen pressures above 180 would not improve performance, but would instead increase stiction & heat which leads to a harsher ride, which in turn leads to faster wear of the seal & shaft.

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I can't remember what Barnum's psi was but it's more then 160 :cry: I think it's was 180 or so let me know what he says. I don't know about the heat part.......but, I do know that the pressure helps seal. I have tried from 190psi to 240 and there didn't seem to be much difference in feel...most of the change was on the big whoops.

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:cry: Does the word "GRENADE" come to mind?

Stock N2 pressure is 142psi.

My local dealer also charged $15 to fill mine to ~149psi (their rig only adjusted in 10psi steps, so I went a bit over rather than under stock pressure.

Does anyone REALLY know what the maximum "Safe" pressure rating is for a stock XR650R shock res.? Really?

Maybe a bomb disposal safety suit, or at least a flak-jacket should be part of every good tool "arsenal". :cry:

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Depending on the type of gas chuck being used, there will be a loss of pressure from where the regulator is set. The Schrader gas chuck (Schrader PN# 556) is the best valve to use for charging gas shocks with minimal loss from what I've seen, but one way to determine how much nitrogen is inside a shock is to remove the spring and check how much force it takes to move the shock's shaft from its extended position. I don't have the numbers for the XR650R shock, but I'm sure someone does incase anyone here wanted to verify how much nitogen was actually inside their shock. I would think 300 PSI would be approaching the upper limits, but that's just a WAG (WildAssGuess) on my part :cry:

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How much gas pressure do you put in to your Bilsteins?I take it they have Schraders?

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There are tons of shocks out there with 200+psi in them no Grenades :cry: The seal would fail way before the shock would come apart. I haven't heard of any shocks blowing the seal body out of the shock or the pladder out and that's what the force of the pressure is against. The shocks that have come apart is at the nut (no threads) or the rod breaking just below the nut. If a shock was to GRENADE it would be from air in the oil.........there are stories of this but, I haven't seen it. Air gets hot and bottom out and boom...well that's the story so, never let there be air in the oil or charge the bladder with air.

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How much gas pressure do you put in to your Bilsteins?I take it they have Schraders?

I looked at my records and seen that I keep my Bilstein 7100's charged at ~185 PSI on my trucks and yes, they have schraders on them. It's probably time to service them again...ugh. I've tried various pressures and understand that 300 PSI is the upper limit according to Bilstein's tech people. I believe Bilstein recomends 200 PSI as a norm / starting point for these shocks.

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If your shocks feel "soft",you may want to increase the gas pressure.yes they should be maintained.250 psi. is what they are assembled/shipped with.Never go below your 185 psi.

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are you referring to Quadsan's Truck shocks or the XR650R...the factory recommends 981 kPa (10.0 kgf/cm2, 142psi) of nitrogen gas...But I'm game to try what Bruce has found has worked for him. If it doesn't work I have been warned and its nobody's fault but my own.

Also isn't the reason they use nitrogen is b/c it doesn't expand or heat up like air (21% O2)? (maybe it takes hotter temps to expand??) Its been a while since Chem Class so I'm sure someone can clear that up but thats what I thought the reasoning behind Nitrogen gas.

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Yes I was referring to the Bilstein truck shocks.Yes,Nitrogen is preferred because it is a more stable gas.Less expansion (due to heat) and will not contaminate the gas chamber with moisture.Typically a bike shock should be charged to 150 psi.

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Yea after reading it all together it was more obvious that you were talking of the truck shocks... no big deal...I'm leaning alot from Ya'll.

Thanks everyone

JT

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Shane Casad at Bilstein had me reduce my nitrogen pressure to 185 PSI for my applications when I dealt with him years ago. Prior to that, I was running 200 PSI and I recall him and others at Bilstein saying 300 was the upper limit. When the shocks were shipped to me, their pressures were inconsistant, so I charged them all to the same pressure. I charge them once a year whether they need it or not. I noticed about 1/2 hour ago that I've got another leaking shock (my 2nd leaker out of 12 7100's in ~4 years of service), but fortunately they're easy to rebuild :cry:

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