Can regular compressed AIR be used in shock?

[ChasYZF]

That's right. I'm trying to see if anyone has ever used regular compressed air in their rear shock instead of nitrogen. I'm aware of the stable properties of nitrogen, especially over temperature, but I don't have any compressed nitrogen so I want to try regular compressed air. My only concern is the heat from the exhaust pipe will heat up the air in the rear shock increasing the PSI. Using air would I need to back off on the 120 psi.? Say something like 100psi. to allow for the increased pressure due to exhaust pipe heating of shock resouvoir?

[huffster]

Dude,

This will not work...Don't do it or you will end up on your head and possibly in the back of an ambulance....Most decent motorcyle shops have a nitrogen tank and will charge your shock for you for 15-20 bucks...Air is simply not stable enough. Not only does the exhasut have some effect, but the oil gets very warm while riding and has the greatest effect on the air temp..

[ChasYZF]

Thanks for the advice.

Just out of curiousity are you speaking from experience? Air is about 60% nitrogen anyway. I guess what I was trying to figure out is the effects of temp. on air vs. nitrogen. Don't worry. I'm going to follow your advice here. I won't be using air to fill my shock bladder. Just curious that's all. You know we use regular air to inflate our tires on our cars and trucks, and that works so I just had this crazy notion that's all.

Thanks again for your input. I WON'T use air I promise.

[buggsz24]

Air will expand much more when heated as compared to straight nitrogen, it also contains water. Both of these facts make it a poor choice for your gas charged shocks

[ChasYZF]

good point: compressed air contains water

Thanks for your input.

Anybody have the scoop on a good nitrogen set up? Like who to buy from and how much the cost?

Thanks.

[ReD_RiDeR_CRF450R]

air is actually 78% nitrogen, but its the other stuff mixed in with the nitrogen that make it expand more when it is heated, etc.

[huffster]

Thanks for the advice.

Just out of curiousity are you speaking from experience? Air is about 60% nitrogen anyway. I guess what I was trying to figure out is the effects of temp. on air vs. nitrogen. Don't worry. I'm going to follow your advice here. I won't be using air to fill my shock bladder. Just curious that's all. You know we use regular air to inflate our tires on our cars and trucks, and that works so I just had this crazy notion that's all.

Thanks again for your input. I WON'T use air I promise.

Many years ago I knew a guy that tried this...and after several endoes and assorted crashes, he asked me to look at his bike...I knew something was wrong with the rear shock, it had no rebound when cold...ride it a few minutes and it became a Pogo stick. I asked him if he had been messing with it and he told me he had "Let the air out" by accident...So, he put air back in....About 50PSI LOL

We serviced the shock for good measure, put the nitrogen back in and he could not believe the difference.

BTW, I've noticed that some of the tire stores will now fill your car, truck or whatever tires with nitrogen. It's said to increase your mileage and not leak out like air slowly does....So, others are catching-on.

[afritts4u]

I recently had braught a shock into RG3 off the bike and they filled it up to spec with nitrogen for free!

[CamP]

In an emergency, you could use air. You would want to keep riding time short to keep the shock cool and fill it with Nitrogen asap. A mountain bike shock pump will do the 150psi you'll need.

[biketrdr]

if you like just go to your local welding supply and buy a cylinder. we keep it in the shop and you cant believe everything we use it on. from tires on the drag car to pressure testing ac systems for leaks ?

[ChasYZF]

Yeah today on Ebay they have 80 cubic feet tanks for sale brand new for $147 plus free shipping. I'm still trying to find a decent nitrogen regulator for under $200 though.

I'm at work right now so I don't have my service manual with me, but does anybody know the specified PSI for the rear shock? I thought it was 120psi, but then again as one could derive from the title of this thread I should keep the "thinking" to a minimum.

[huffster]

I think most run around 170 Psi on big bike shocks

[CamP]

Both Showa and KYB spec 142psi for their shocks. Most suspension guys use 170psi like huffster said.

[thak]

hello, I have used 217 PSI (15bar) in my shocks during over one year (shimmed about 5 times) without any problem. Theoretically this might of course affect something, as adviced pressure is about 145psi, but I haven't noticed any difference.

The one shot to charge the shock is about 2$ in the fire extinquisher shops, and it is not worth to use air in moneyvise. My guess is that the water in normal air may cause some problems, esperially if ridden in temperatures below zero

[james509]

Aw Fooey, You can probably use compressed air without any problems whatsoever. All the air pressure does is keep pressure on the oil to keep it from cavitating at high shock piston speeds. True, nitrogen would be better, It is dry and doesn't expand as much with heat although it still does, compressed air will get you by just fine until you can find some nitrogen.

[nexrace]

I'd would wait till I got the $2.00 for the fire extinguisher guys before I'd risk a trip to the hospital.

[punkrock MX]

if you want showa shrapnel in your hine' portions..go for it! ?

not a good idea!!

[450 vet]

old post but air can be used in a pinch.i prefer nitrogen myself but for the average rider,they wouldnt be able to tell the difference.this is from what i have seen not "heard".im not going to get into the thermal dynamics of it but air is possible to use.u dont think a suspension company ever ran out of nitrogen and used a replacemnt for a customer?most guys know nothing about suspension anyway so how can they confirm theres nitrogen in the bladder?exactly...

[Maddog10]

old post but air can be used in a pinch.i prefer nitrogen myself but for the average rider,they wouldnt be able to tell the difference.this is from what i have seen not "heard".im not going to get into the thermal dynamics of it but air is possible to use.u dont think a suspension company ever ran out of nitrogen and used a replacemnt for a customer?most guys know nothing about suspension anyway so how can they confirm theres nitrogen in the bladder?exactly...

He's right... I've ran air in my rear shock for a day before until the local shop restocked on nitrogen, and like 450 vet said, most riders would never know the difference. I wouldn't recommend running it all the time since nitrogen isn't generally hard to get, but more than likely you will never know a difference between the two.

[KVSteve]

Edit

Edited April 15, 2014 by KVSteve