I recently took a lady friend for a ride on the bike. We bottomed out on every little bump. Neither she or I are unusually large. But even before that I noticed that the bike was very spong feeling in the back, and I would almost bottom out on even the smallest bumps while riding alone. I pondered the situation, then remembered the shocks are air assisted. Went to a garage, and tried to get a reading of air pressure in the shocks, but couldn't because the air would be let out of the shock as soon as I touched the air nozzel to the intake of the shock. Anyway, to get to my point, I was able to put air into the shocks. Now my question, how much pressure should I be running in them for a safe and smooth ride?
Wayne

Good rule of thumb seems to be..
Rear shock air pressure (10% of total load weight)

YIKES, that means that I'll have to ask the weight of every woman I take for a ride on the bike. Guess I getter get some cheek protection, might get slapped a few times :D Thanks for the advise

Wayne :)

Just ask AFTER you put the full face hemet on. Of course that leaves other areas vulnerable. Best to do a silent estimate and I'm sure if you come close the ride will be a bit more comfortable.

I found a special low volume hand pump at a bicycle store. The mountain bikes use air springs. It cost $30, has a built in gauge and when I disconnect it from the shock, I lose hardly any air. The chamber for the air spring is pretty small. Everytime I checked the pressure with a regular air gauge, I lost about 5 pounds of pressure. You shouldn't try and fill them with an air hose at a garage. The maximum pressure is 43 pounds and overfilling can blow a seal. If you have a compressor at home, and can adjust the pressure to the 5 to 40 pound range with the built in regulator, you can use that to fill the shocks.

A quick question what is the stock air pressure?
So i'll know where to start
and thanks ahead of time!!!

There is no "stock" air pressure for the rear shocks.
The general guide is 1 lb of air per 10 lbs of rider/luggage weight.

So if you weigh 200 lbs you would put 20 lbs of air in each shock.

Do NOT use a regular air compressor to do this. Either get the special hand pump, or, get an air tank, fill it/bleed it to the pressure you need (e.g. 20 lbs) and give each shock a quick shot with it. The shocks only take a very little bit of air compared to what is in the compresor tank, so they will be even enough in pressure.

RB

A quick question what is the stock air pressure?
So i'll know where to start
and thanks ahead of time!!!

Thanks, RB. I just bought a 2001 VN750 Monday, and was wondering why I was getting jolted so hard with every bump in the road after all the magazines complained about the "mushy" suspension.

The shocks are loaded with SEVENTY PSI. :doh:

I'm 215 pounds, so looks like I'll set 'em at 23-25 PSI to account for my gear.

Dang, I should check my shocks. Evertime I hit even a moderate bump, I'm sure that my kidneys move about 5 inches.

I have about 5 psi and the shock set to 4. With the wife on the back (we total about 275) the ride is pretty good.

The shocks are loaded with SEVENTY PSI. :doh:

I'm 215 pounds, so looks like I'll set 'em at 23-25 PSI to account for my gear.

I hope that your rear shocks are not really loaded with that much air. Putting in 70 PSI would blow the seals on them. :BLAM:

I have a Progressive air pump which I use for my shocks. On my VN750, I run Progressive rear shocks which don't have air-fittings but I have modified my front forks with a set of older VN750 fork tubes with the air fittings and run around 12 - 15 lbs up there along with Progressive fork springs. Very smooth. On my Nomad, I keep around 24 PSI in my rear shocks unless I'm doing some heavy duty two-up riding, then I go around 30 PSI. Never more...

The shocks come at 0 psi from the factory. I have my shocks at 30 psi and rebound at 3. Works for me, im 230 lbs

My shocks had air in them when new. Must have been the dealer.

Umm, I've never checked mine !?
I've never thought it to be that uncomfortable. Maybe I can still get more comfotable !!
I know what I'm checking today.

What exactly does the rebound setting do?

Umm, I've never checked mine !?
I've never thought it to be that uncomfortable. Maybe I can still get more comfotable !!
I know what I'm checking today.

My bike is just over a year old and I never checked mine until just a few days ago. My shocks have 0 psi. Using a hand pump I tried to air them up and the pressure leaked back down to 0 psi almost immediately. I guess my seals are shot.

Either my dealer aired them up with a compressor before I bought the bike (ruining the seals) or they have just deterioted to the point they won't 'seal'.

My guess is that they have been this way since day one.

Should I be concerned about repairing this or just live with it. The bike rides the same to me--of course I wouldn't know the difference if they have in fact always been blown.

BTW, my owner's manual list 71 psi as max.

Can you hear the air leaking anywhere?
Maybe it's just the valve itself needs changed. There is also an O-ring with the valve. Maybe it's that.
Ron Ayers lists the valve assembly & O-ring for $13.27 per side.

The owners manual also says for an average rider of 150lbs w/ no extra gear, atmospheric pressure is standard.

Is there any oil leaking out ? If not you should be ok.

Is there any oil leaking out ? If not you should be ok.



There is no sign of an oil leak on or around the shock itself. There was oil associated with the valve stem when I was trying to air them up. It was basically leaking out of the valve stem as was putting the air hose on and off. But otherwise, no oil leak.

How does that make it ok?

The owners manual also says for an average rider of 150lbs w/ no extra gear, atmospheric pressure is standard.

That's interesting and opens up another can of worms. Atomspheric pressure is ~15 psi, which would correspond to the 10% theory for a 150 lb. rider. If I weigh 200, would it not follow that only 5 more psi would be needed?

Atomspheric (15 psi) + 5 psi = 20 psi for a 200 lb rider. Or should it be atomspheric plus another 20 psi?

There is no sign of an oil leak on or around the shock itself. There was oil associated with the valve stem when I was trying to air them up. It was basically leaking out of the valve stem as was putting the air hose on and off. But otherwise, no oil leak.

How does that make it ok?

No oil leaking would mean the shock isn't leaking at all, meaning the seals are probably good.
My guess is still the valve and/or O-ring. You could probably get just an O-ring at a hardware store for a few ¢'s and try that first.
If you do remove the valve assembly, it'd probably be a good idea to lift the back of the bike (from under the motor/frame area) until the wheel is off the ground, so the shock wont have any pressure on it. Ya don't want the oil spraying all over the place when the valve is removed.
Then again, if ya don't have a problem with how it rides now, don't worry about it.
Oh, yeah, 20psi would be what you'd want if ya do get it to hold air.

mine still have no air due to the fact I haven't bought a pump as yet, but I was told by a mechanic to slightly over fill the shocks then bleed them down to where you want them using the pressure gauge that you are checking them with

My bike is just over a year old and I never checked mine until just a few days ago. My shocks have 0 psi. Using a hand pump I tried to air them up and the pressure leaked back down to 0 psi almost immediately. I guess my seals are shot.

When you say "hand pump", what do you mean??? A bicycle pump will not work and could damage the seals. You need a pump like the progressive air pump for shocks with the no-loss connector.

http://www.accwhse.com/photos/progressive_pockt_pump.gif or http://www.amotostuff.com/Merchant2/graphics/00000001/progressive_suspension_GP3-pump.jpg

With this, you can put in exactly as much pressure as you want, measure it right on the pump without losing air and disconnect and be done... Using an airpressure guage from a bicycle will almost drain the air in the shock as it is trying to get a reading.

They are pricy, but I have found many uses for mine. I paid around $45 for mine...

What about using an air compressor where you can set the pressure?

And the big question is, why do you want to put air in your shocks anyhow? If it needs to be firmer, just use the adjustments on the outside. So, what do I not understand about mechanical adjustment vs. air pressure?

And the big question is, why do you want to put air in your shocks anyhow? If it needs to be firmer, just use the adjustments on the outside. So, what do I not understand about mechanical adjustment vs. air pressure?

Ditto. :confused:

And the big question is, why do you want to put air in your shocks anyhow? If it needs to be firmer, just use the adjustments on the outside. So, what do I not understand about mechanical adjustment vs. air pressure?

Well, I'm not an ex spurt, but the air sets a starting point--literally how firm they are before you sit on the bike or hit a bump. The mechanical adjustment, or dampening, regulates how rapidly they recover or bounce back. At least that is my understanding. They are definitely 2 different adjustments.

When you say "hand pump", what do you mean??? A bicycle pump will not work and could damage the seals. You need a pump like the progressive air pump for shocks with the no-loss connector.

A bicycle pump will work, it is not stout enough to bust the seals. Not when it takes multiple strokes just to put a few pounds in. Where it does fail is that it doesn't have the type disconnect your pump has and leaks pressure when the hose is removed. The one I use has a gauge so you can see the pressure build as you slowly pump it up. In my case, before I ever remove the hose, the pressure just as rapidly goes back to zero--it is leaking somewhere, I just haven't found where.

You are right on the difference in the two... air gives strength and the adjuster controls speed of travel.

If you think that your shocks are trashed or would like to get another set there are three sets now on Ebay starting at 9.99 and one set at 65.00.... Just FYI

http://search.ebay.com/search/search.dll?sofocus=unknown&sbrftog=1&fcl=3&catref=C5&frpp=50&from=R10&satitle=vn+750+shocks&sacat=-1%26catref%3DC6&sargn=-1%26saslc%3D2&sadis=200&fpos=ZIP%2FPostal&ftrt=1&ftrv=1&saprclo=&saprchi=&fsop=1&fsoo=1

I just added 20 lbs to my bike's back shocks. The last few times I've parked at work, I bottomed out on the curb. I imagine it's my weight gain over the last few years. I screwed my shocks in to the max (4 or 1, their under my bags and I can't see), but I guess that is how hard it's gonna bump back, right? Knock me off the bike, it will. So, if I understand this right, by gaining weight, I was required to up my pressure in the shocks form 0 to 20, correct?

Correct!!! you win the speed bump award!! ;)

BTW... for those who said max PSI is 71....read it again... if pressure exceeds 71 psi you risk damage to oil seal! usuable range 0 - 43 psi !
And DO NOT use compressed air... you will most certianly blow the seals!! The volume of air is not that much and you will go way over 71 psi real fast!!
That is why they tell you to use a bicycle pump.

so can someone give the psi ranges for weight of rider alone?

100 lb rider = x psi
135 lb rider = x psi

etc

and can you check the psi without losing too much pressure with a regular stick air guage?

And DO NOT use compressed air... you will most certianly blow the seals!!

Like, how would you get compressed air in the shock if you can't use compressed air? I don't think that's what you meant. I think you mean DO NOT use an AIR COMPRESSOR. But then, what do I know?

I did use an air compressor, but I dialed it in at 20 lbs, and filled the shock til full, at 20 lbs.

As to blowing the seals, as the penguin said to the mechanic, "No, No! It's ice cream!"

As to blowing the seals, as the penguin said to the mechanic, "No, No! It's ice cream!"

Leave your personal life out of this!!

so can someone give the psi ranges for weight of rider alone?

100 lb rider = x psi
135 lb rider = x psi

etc

and can you check the psi without losing too much pressure with a regular stick air guage?

There isn't enough air in there to check it that way. As soon as you do, enough will leak out to change the pressure. Unless, you put in much more than what you need, and you have one of those gauges that you can bleed some of the air.

As to x psi, I wouldn't worry about it. If you don't bottom out over bumps, there isn't really any need to mess with it. I've gone 7 yrs, and this is the first time I've bottomed out. If you read back through this thread, it suggests that atmospheric pressure is fine. Which you would think to be 13 psi, but it's a relative thing. If you hold an air pressure gauge in the air, it won't read 13 lbs, it will read 0. So as long as there is 0 lbs in the shock, it is atmospheric, and that is OK. I used 20 lbs, because I don't have a clue as to what it should be.

Oops, I should follow my own advice.

1 lb for every 10 lbs of load. So for me, being 140 plus my clothing, I weigh in at around 240, so I should be running 24 lbs. So, as to fill the formula,

100 lb rider = 10 psi
135 lb rider = 13.5 psi

etc.

[QUOTE=arkjeff]The mechanical adjustment, or dampening, regulates how rapidly they recover or bounce back.[QUOTE]


okay, so what should I have the dampening set at? Say, for 150 to 200 lbs..( my laptop weighs at least 50 lbs.) How do I figure it out on my own...?

Um, you need some sleep. 10% of the weight. Take that thingy the nerds use, has all the numbers on it and a cross, a line, an X, and a leaning line, like an eyelash, and enter the number of the weight. Then push the X. Then push the dot, followed by the number 1. Now push the equals. It is two dashes, one above the other, like this =

That is the pressure you need to set it at.

Back to the book...... ;)

Average built rider... 150 lbs.( with no accessories ) good @ 0 psi.
chart is load light, road good 0 psi provides soft settings
as the load increases, road gets bad then up the pressure as you see fit.. up to max of 43 psi.

I use an aggu-gaugeLike the one here http://cgi.ebay.com/ebaymotors/Accu-Gage-60-PSI-Range-Tire-Air-Pressure-Gauge_W0QQitemZ120025763879QQihZ002QQcategoryZ3374 6QQssPageNameZWD1VQQrdZ1QQcmdZViewItem

after you pump up the shock just hold this on and leak down to the pressure you want with a button!

BTW Arkjeff.... did you say that you had oil coming out of the air valve??? some one might have tried to do a re-fill of the shock oil! just saw that in "the book" to re-fill the shock oil you are to FILL the shock and then pour out a pre-determind amount that they call air chamber capacity... all of this is done through the air valve opening.

No Cegodsey, I am talking about the little numbers on the shock itself. the 1, 2, 3, 4. Which one?

Presently, I have it set on 2.

And thank you, I slept very well.:rockon:

No need to be that scientific. Putting in 20psi will be fine

I have mine on 2 when it's just me, with additional weight on the back (wife) I click it to 3. I don't even know she's back there until I here the voices in my head telling me she needs a break, or she gets smacked on the leg by a grasshopper. Bike does a little jerk and someone goes "@#$@# that hurt!"

That's the info I was looking for...

thanks:notworthy

i'm at 165 lbs. have mine set to #3 and no preload presure. tried 1,2 and it while it was very smooth ride i hated how it felt when cornering hard. now it is more bouncy but not dipping right away as i corner. i guess try it at each setting and decide what you like the most for your ride style.

progressive rear suspention next on the list.

will do... had it at one, but didn't like the ride on the superslab... Do more riding now on smaller roads, and it seems to like 2. Will leave it like that for a while. I don't think I am going to worry too much about the psi settings...

Oooohhh, that adjustment. You shouldn't hafta remember which is softer, and which is harder. If you tighten it (righty tighty), then you are compressing the spring, which makes the spring more jumpy. I JUST YESTERDAY figured this out. I have been riding with it at two. Like tankist said, it depends on what YOU like.

what the heck do you mean by "jumpy". is the damn thing going to buck me off if I tighten it down to four?

Yes.

higher number - stiffer ride

I have a small air tank that I fill with my air compressor this tank has a valve on it where you can let the air in slowly .ThenI use a tire pressure guage that has a small push button on the side of it to let air out if you need to works great.............

I just checked the rear shocks on my 04- no air in 'em- at least none registered on the tire gauge or hissed out. I used one of them foot petal air pumps with the attached pressure gauge and squeezed the air in by hand. Barely two or three squeezes got me up to 20 psi. I'm 215lbs, and the shocks are set to "2", which seemed fine to this newbie over the last 500 miles with no air in the shocks. I look forward to the next ride.
Thanks to all for your ongoing advice.

mind if I resurrect an old thread? I found the answer to how much air in this thread (thank you). Still figuring out the shock adjustments. When I go into corners and the road is bumpy, the bike starts bucking. I worry that it will cause my tires to lose contact with the road (and I like the corners). Loosen the setting by 1?

I recommend 0 psi, or atmospheric pressure, which is what the manual recommends. I weigh 200 pounds, plus gear, plus I have a lot of accessories, and keep my saddlebags full all the time. So I have always kept the shocks set on max preload. I have taken my youngest daughter for rides many times, and had the suspension bottom out. But, with her weight, my weight, and the weight of the cargo and accessories, the bike is seriously overloaded, and I would expect it to bottom out occasionally. Only the suspension bottomed out, being aware of the issue, I was very careful, and have never actually banged the bottom of the bike on anything. The pegs do drag easily with that much weight. My guess is, with any significant amount of air in the shocks, instead of bottoming out, it would just blow the seals.

I managed to put over 80,000 miles on a new '93 without ever having any problems with the shocks, and I credit not ever putting any air in them as part of the reason for that. Unlike car shocks, motorcycle shocks should last the life of the bike, or at least the bikes engine, which I'm estimating to be well over 100,000 miles in the Vulcan's case. Jerry.