front air forks

[dtkid]

Hey folks:

I need some knowledge/assistance with the front air forks on my 1980 GS1100E. My Clymer manual don't say squat about the air component of my front shocks. When I went to check the air pressure there was none. Also, when I went to put air into the valve...it would not take air. I moved the round collar down on the fork and noticed the "hole" in the fork tube. Does this line-up with a hole in the collar?

OK........could anyone briefly explain the operation of these air shocks...I sorta don't know where to start...I understand the workings of normal/stock Suzuki front forks but this "air-component" is not part of my knowledge base. HELP!

[dtkid]

Now that ya'll have help quell my PayPal rebellion how bout' explaining my front air shocks...............

[JayH]

You can't put any air into the forks using a gas station air hose. The connection was made like that so the unknowing rider couldn't blow out the seals in the forks.

Your best bet is to go get one of those small bicycle pumps that have a gauge and hose. Hook it up to your forks and put ~10 psi.

Do you have a manual for this bike or any of your Suzuki's? Lots of the GS bikes have air forks.

[AOD]

Your best bet is to remove the stock springs and install a set of progressive front springs instead. They're much firmer than OEM and there is no need to use air pressure (which sounds unreliable to start with) in the suspension.

I know...I know...it's easy to talk the talk. But I think many here will agree with me.

~Adam

PS: If you must use the air, I believe there is a valve you have to open to add air.

[KGB]

I agree with Adam.
I don't run any air in the forks.
I have Progressive springs, ran them in both bikes.
The 1100 is gone, but I'm pretty sure the new owner feels the same.
I run 20 weight oil in the forks, firm but not rock hard.

Some here, and I agree, say that air in the forks will/can mix with the oil causing it to break down or loose viscosity.

There is a schrader valve located on the fork or around the triple tree.
My 1000S has individual air caps on top of the forks, so each one is done seperately. The 1100E had a single valve for both forks located on the right side, sitting on the bike, near the reflector mounted on the fork.

Don't use more than 10psi as this could damage the seals.
Start off with 5psi and see if you notice any difference.

The Progressives are around $75-$100 USD and worth it.
Cartridge emulators are expensive.
I think Joe Nardy just did his forks with the emulators and posted about them.

[fgh]

Why Air Shocks?

The short answer is that they allow a rider to tailor the motorcycles ride and handling characteristics to suit him or her. Adding air is something like increasing the spring force or increasing the preload. It doesn't change the fork movement in exactly the same way as changing or preloading the spring. Try different levels of pressure to see if you can find one you like. If you want different performance for different kinds of riding this would likely be helpful.

The collar that has the air valve in it does not have to line up with the hole in the fork tube. There is an indentation on the inside of the collar that allows the air to travel from the inside of the valve around to the hole. The indentation or valve need to be set at the same level as the hole in the fork.

The really annoying part is adding and adjusting the air. You need to be careful and not fill above the Suzuki maximum pressure. Doing so could blow out your fork seals. The tricky part is getting to the pressure you want. There is no elasticity in the fork system like there is in a tire. When you inflate a tire it stretches thus increasing the amount of air required to get to the desired PSI. With the forks there is no stretch and a small volume of air to work with. You'll need a manual pump that you can slowly increase pressure and then disconnect with very little loss. Most of the manual pumps have the latch able type air chuck. The problem with the chuck is by the time you unlatch it and pull it off you'll lose all the air. If someone reads this and knows of a pump that is well suited please let me know about it.

[snowbeard]

well, they certainly make a pump that will work, it is a nice highly specialized tool...

they also make a not so specialized syringe pump with no pressure guage so you have to count the pumps, check the pressure. then check the pressure again to see how much you let out checking it the first time. then let all the air out and pump 3.5 times. check the pressure to make sure you've got a good average, then recheck, then let it all out and pump 3.5 times and don't check it again! repeat on other shock....

also, be careful with even a bicycle pump, as the volume of air in the shocks is definitely less than one pump cycle, you can get 50 PSI if you're not careful, and that will blow your fork seals.

check the orings on the air valves, they just unscrew (do this with no pressure btw) mine leaked there and held no pressure.

the clymers manual says 7 to 11 psi.

good luck!

[dtkid]

thanks guys..........I'll be working on the forks this weekend while I attempt my first motorcycle tire mounting event.

I'll let ya'll know how it all comes out.

Answer to Jay: I have Clymer manuals for all my Suzukis but I swear they say nothing about the "air-component" unless of course I was having one of moronic episodes. I'll check again.

[duaneage]

Here is how I do it.

I adjust my air compressor down as low as it goes and fill a bicycle tire up. I then check the pressure in the bike tire with a digital tire pressure gauge, not those crappy plastic ones. If it is too high I deflate the tire and lower the regulator and test again. When I have 10 pounds coming out of the regulator I use the airchuck to inflate both forks. I test it again on the forks and it always comes out at 10.

I am going for progressives myself this year because this procedure is a PITA.

[fat_sac]

Wow, you guys are really careful when you do this. I just hit it with my air compressor and use a pressure guage to let air out until it reaches about 10#'s. I didn't think about the o-rings leaking. How do you know if the fork seals are bad? It's not leaking oil now, but my front brakes don't work like they've been hit with an Exxon oil spill can.

[Doctor Shifty]

Here's some more long answer stuff for the air forks.

Inside the fork tube there are three things that make a difference - the spring, the oil, and the air.

The spring will work according to how it is made, either flat rate or progressive, and you can't adjust it except by replacement.

The oil is adjustable by using different grades, anything from 5 to 30 grade. The bike is best at about 20 grade but personal preferences will swing it a bit higher or lower.

The oil is also adjustable by quantity. If you put more oil in then the air space is reduced and it is that air space compressing that effects the action. More oil means less air space therefore higher compression with smaller movements of the wheel, so reduced effective suspension travel. Less oil will mean more air space and greater travel until it compresses. This air space acts in partnership with the spring rate. It is like having a fine adjustment on the springs.

If you use the standard oil quantity (therefore standard air space) you can also pump the pressure up a little. This has the effect of giving another adjustment - but what exactly is being adjusted?

The answer is, pumping up your forks gives a slightly stiffer ride but allows full travel of the forks. If you are riding at highway speeds over rough country roads you can pump up the forks a bit and get a better ride. The smaller bumps will be handled by the spring rate alone, but as the air compresses it will start to take control of the compression rate.

Pumping up your forks is a bit like having progressive rate springs - not totally like it but a bit like it - it's the earlier version of progressive damping.

If you look at what is happening in dirt bike racing these days, where long fork travel is essential, you will find that people are now putting an air tank of a pint or so capacity on top of their forks with a contollable bleed pipe to each fork leg. This gives a large air reservoir for the top of the fork oil. The rider can adjust on the run how much effect this has so he gets even more fork travel by adding more air space above the oil.

And the irony of all this is that these Suzukis of the early 80s had the air fitting, many people didn't understand it, and then progressive springs took over the theory, and the air systems went out of fashion. Now aftermarket air systems are being added to high tech dirt bikes.

Kim

[Doctor Shifty]

The second bit

Several people have told you to limit air pressure to about 10 psi. Here's how to do it.

The air collar sits against a circlip in the fork leg and is held at the correct place. If you have a system that moves it might be that it has been added later. You don't have to line up any holes, just make sure that the hole in the fork leg sits about the middle of the collar. The collar has an o-ring top and bottom to seal it.

There are two controls, the equalising bleed screw and the valve.
Open the equaliser screw a few turns. Take the cap off the valve.
Get a hand bike pump that pushes directly over the valve.
Pump it about five times and check the pressure. It doesn't take many pumps.
Test it a bit for how many pumps to take it to 5psi, 10psi, 15psi. Don't take it higher.
Let air out to take it back to 8-10psi.
Close the equaliser screw and recap the valve.

If you want to see what the system is really doing, find a roughish road and have no air in there. Then pump it to 5psi and ride again. Then pump to 10psi then max at 15psi. Try to "listen" to how the front wheel is handling the bumps - stiffness as well as travel.

The system should handle 15psi OK, it is only when the forks get very compressed over a bump that the pressure will rise to a level where it will blow a seal.

Kim

[Sandy]

Your best bet is to remove the stock springs and install a set of progressive front springs instead. They're much firmer than OEM and there is no need to use air pressure (which sounds unreliable to start with) in the suspension.

I know...I know...it's easy to talk the talk. But I think many here will agree with me.

~Adam

I agree totally. For quick fix you can increase the length of the spacer inside the fork by about an inch or less, or add a bunch of large washers. Changing the springs is the way to go however.

[dtkid]

I am still amazed that my ignorance still amazes me. I swear I checked all over the front fork section of my Clymer manual for the explanation of the air pressure component of my GWS1100E forks, however, yesterday I went home and looked again and low-&-behold, the information was there!!!

Man, the seventies must have been more detrimental on my cerebrum than previously thought.

[Billyboy]

I think mine's messed up.

How low should the forks be under weight? When I sit on my 78 GS1000 it looks like I have about 2 inches of travel to bottom it out. (I'm 215 + clothing.) Is that normal? I haven't checked the pressure or oil level. How much oil for my bike?