Stick a fork in this Newbie

[BriTXbike]

I've posted a few things here already but I've probably spent a combined total of 15+hrs reading through this board with the mounds of useful information that I have to gain from dedicated owners.

A little bit about myself: I'm in Dallas Texas and brand new to the Motorcycle world (now wondering why I didn't get into this earlier!). I went through a rider safety course; you would to if you knew the crazy drivers around these parts. After my two day course I went got my license and was on motorcycle trader that afternoon. Being new to this I figured a safer route of buying a cheaper bike cash. Little did I know I purchased a Gem of a bike and a maintenance crew to go along with it ;-) After reading, what seems every post, I?ve decided that this bike won?t be a temp bike anymore. Anyways I ended up with an 83 GS850G (Miles:29,000). Probably paid a little too much for it but at the time I was chomping at the bit to ride and at first glance the bike looked solid. I?ve had it for about a month now and after riding for several days and new rubber I?ve started to asses what needs to be done to the bike to get it back in tip top shape. She runs pretty well now but little things like gasket leaks, reupholstered seat, and cracked plug wires are on my list of things to replace. That?s another question for another post. MY MAIN QUESTION has to do with the front fork, as I don?t want to ride if this will negatively effect the repairs down the road.

Now I?ve read a good amount of posts and I didn?t really find the answer I was looking for about this. So the fork is fully extended when the bike rests on the side stand and when I sit on the bike it immediately depresses about 1 ? (inches). I?m guessing this is normal? More of a concern is I approach a light and start in on the front break. The fork will depress up to another 2 1/2 inches but doesn?t bottom out. When I come to a complete stop the fork will not return back to its original point. Now if I hold the brake and roll back slightly it will move the 2 ? inches but not unless I do that. So what?s the diagnosis people? Do I need to rebuild the forks?

Thanks again in advance for everyone?s help cuz I?m gonna need it.

[gspaul]

An easy thing to do first is change the fork oil,something around 15wt.
But it does sound like you have lost a bit of tension in the spring,
is thereanything at the top of the fork's to adjust preload?
If not,you can put in a spacer on the top of the spring to increase tension, or you can buy new progresive spring's for a better ride.
Either way your fork oil will need to be changed, and it's easy to do.

[BriTXbike]

Who said ya need a manual!?

LOL I do! I just ordered a Hyanes manual to help get me started. I assume the adjustment should be a bolt at the top of the shaft. The previous owner said he changed all the fluids but I'll probably change it anyways so I know how to for future reference.

A side question I have to this is Seals. Are the seals only used to contain the oil inside the shaft or are there internal seals that can be changed out that might cause the sicky problem. When you say easy to change are we talking pumping oil out or is there a drain plug a the bottom. Again probably something the manual would say but I not one for patients when it comes to finding a solution. That and I have the next three days off :P

Thanks for the quick response paul!

[gspaul]

Not overly familier with the various 850 model's,but there is normally a small bolt towards the bottom of the fork leg,that's your drain bolt,do one at a time and just pump it out.
If it's not there you may have to remove the bolt/cap at the top of the fork, remove the fork and tip it upside down.
If you have adjustable preload it will have a central bolt in the top cap, it's spring loaded and you will see a change in hieght of the bolt,if it is adjustable.
The fork seal's are really the only one's you have to change,but sometime's they can cause fork"stiction",the upper part of the seal is dry and griping the leg,but if there not leaking or don't want to change the ,a little bit of oil round the top of the seal free's thing's up quite well.
But it's mainly down to springs/oil.
Welcom to motorcycles

[tfb]

The other things that can cause 'stiction' are:
1. Slightly bent forks. Only way to pick it sometimes is dismantle the front end and roll them on a flat surface. If slightly bent, they can be straightened by the right specialist.
2. Forks twisted in the yokes. This is easy to rectify; simply slacken the upper steering yoke pinch-bolts, give the forks a bit of fore&aft movement down the axle end, tighten the pinch bolts. Then, repeat for the lower steering yoke pinch bolts. (Don't undo upper and lower bolts at the same time, or else... :roll: .)
3. Bottom end of the forks are either spaced too widely on the axle, or too closely; ie. the forks are not parallel. Fix this by following the correct procedure in your Haynes manual; at one point in the procedure, you will be told to plunge the suspension up and down -- this is to get the fork lowers at their correct spacing on the axle.

Certainly it sounds as though your springs are a bit on the tired side; 1 1/2 " sag is a bit too much. You should have a bit, though, so that your suspension doesn't 'top out', ie. hit the upper limit of extension with a bang after you've gone over a bump. If you are after a clear, user-friendly article on the basics of tweaking your suspension settings, read the article by Patrick at http://oldskoolsuzuki.info/ ... he's has done an excellent write-up; once on the site, navigate to 'Seven-Eleven' and then the link to 'Suspension Setup for Dummies'

Keep at it,
Mike.

[jimcor]

I'm gonna agree and disagree.

Change your fork oil. You can use ATF, automatic transmission fluid. Your manual will probably tell you SAE 15. Which just happens to be the weight of ATF. In fact go to your Suzuki dealer, they sell it... for a lot more than Auto Zone! Use some old Dexron or Ford type fluid, and tell the dealer to keep the $7 a bottle stuff!

Your seals are at the top of the fork slider, there are no internal seals. If your forks aren't leaking (and they do have oil in them! ) then leave them alone. One trick is to use an ATF sealer (seal sweller) for a vey small leak.


Now that 2.5 inches of spring sag. Normal. Nothing to worry about.

Your forks will not be fully extended on the sidestand. On the centerstand if you push down on the rear of the seat to raise the front wheel, then the forks are fully extended.

Also the way your forks are acting after a stop is normal.

Down the road, after you get everything dialed in, and more importantly get some miles under your wheels, and meet with the many other GS owners/riders in Texas and across the country. You may decide to put in new fork springs. A set of Progressive suspension springs will fit the bill. And new shocks. But don't worry about this now. There are other issus that you 'll need to look at... Swingarm bearings. Steering stem bearings. Gel grips.


Welcome to motorcycling!

Make a small fortune. Just bring a large one to start!

Ain't it a hoot!

[Travellin' Jones]

The GS 850 is equipped with air-assisted forks, which should be run at 8-16 psi. Put the bike on the center stand and then raise the front so there is no weight on the front wheel. Both legs should be set to the same pressure. You'll lose about 1 psi every time you check pressure, so put in a little more than you want and then slowly release it until it's about 1 psi more than you want. Use a hand pump to add air. Because the air chambers are so small, it's easy to overpressurize. It takes a little practice to get right.

I'm going to disagree with a couple of things Jimcor wrote. One is that there are seal rings on the damper rods which can wear and reduce damping effectiveness. Also, these rings seal against the inner surfaces of the fork tubes, which can also wear.

I don't know the viscosity of automatic transmission fluid, but am pretty sure it's a lot less than 15w oil. You can see the difference when you pour it. ATF is made for a different job than fork oil, with different additives and properties. A couple of pints of fork oil shouldn't break the bank. In addition, using a higher viscosity, such as 20w, will help compensate for wear in the forks.

[duaneage]

If you change the oil you should remove the forks and flush them with solvent and make sure they are clean through and through. I mounted mine straight up on a bench and refilled the forks with fork oil, not ATF. ATF seemed a bit thin to me so I got a second mortgage and bought some fork oil.

I measured my springs and they were the same as each other and within specs, They also go in a certain way, make sure you don't put them in upside down. You can use a vacuum pump to get the oil level right, i used a ruler and looked down inside with a flashlight.

I run about 22 psi in my 650 forks, some people run no air at all. I would try air in yours. Make sure the air crossover tube ( if equiped) does not leak after you put air in, spray some windex on it and look for bubbles.

I used an air compressor to fill my forks. I set the pressure to about 20 psi and inflated a bike tire. I checked the pressure on the tire with a very accurate gauge. Then I filled the forks. You must add the air then quickly release the air chuck so it does not escape. The forks are very small and quite a bit of air can get past the air chuck if your not fast enough. Checking the air pressure itself lowers the total amount in the tubes.

[bwringer]

I also have an '83 GS850. I am, um, sorta heavier than average, and I ride very hard.

I use Progressive fork springs with 3-1/2 inch preload spacers (yes, it took a goodly portion of my significant mass to push down hard enough to screw the fork caps back in). The fork package recommended something like 2-1/2 inches, which would be a good place to start for less aggressive/bulky riders. And a lot easier to install.

As far as fork oil, I use 15W with 10% "motor honey" mixed in. "Motor Honey" is really thick stuff intended to quiet down the rattling in old car engines, at least long enough to sell them off. In a fork, it makes the oil even thicker, and seems to really help the oil stick to the moving parts -- the motion becomes noticeably smoother.

Granted, my forks have 66,000 miles on them, so with your lower mileage (less internal wear) and less of an all-out riding style, you should probably stick to 10W fork oil or ATF. I would still recommend mixing in a bit of motor honey for fine tuning damping action and the reduction in stiction.

I also use no air pressure -- a preload spacer is far more reliable (Losing air pressure while riding is a real bummer. And dangerous.) and easier on the fork seals.

The oil comes out via the small phillips-head screws at the bottom outside of the fork legs. Flush with mineral spirits or a similar solvent that won't attack rubber seals. You won't believe the crud that comes out.

After draining, flushing, draining, drying overnight, etc., I always like to flush through a quart or so of cheap ATF to rinse out any leftover solvent. Once that's done, refill the forks with your fork elixir of choice to 140mm from the tops (I think/hope/vaguely remember that's the spec for the '83 GS850) with the springs OUT and fork fully COMPRESSED. The Haynes and clymer manuals show a contraption you can easily make from a suction gun or syringe and a piece of tubing. You overfill a bit, then slurp out fluid to the correct level with your syringe/tubing contraption.

Remember, the most important part is that the fork oil LEVELS must be the same -- you CANNOT just dump in a certain amount and forget about it, especially with aftermarket springs. The LEVELS must be set correctly, and within 1mm of each other.

Then order up Progressive shocks and springs for the back and enjoy...

[Anonymous]

After reading all the excellent replies, you may be excused if you're confused. First thing you need to do is find out if you have air forks. Got a Schraeder valve in the fork cap? Air forks have a spring in them but its only there to keep the forks from compressing fully if you lose air. If your seals are gone, the air will also be gone. Once you know what you have, check the manual, service the seals and fork oil, and go with the advice already given. And believe me when I tell you-ten minutes with the manual MAY save you a lot more time when you start the job - not to mention buggered parts, etc. Don't ask how I know this :roll: Cheers!

[duaneage]

After draining, flushing, draining, drying overnight, etc., I always like to flush through a quart or so of cheap ATF to rinse out any leftover solvent. Once that's done, refill the forks with your fork elixir of choice to 240mm from the tops (I think/hope/vaguely remember that's the spec for the '83 GS850) with the springs in and fork fully extended. The Haynes and clymer manuals show a contraption you can easily make from a suction gun or syringe and a piece of tubing. You overfill a bit, then slurp out fluid to the correct level with your syringe/tubing contraption.

Remember, the most important part is that the fork oil LEVELS must be the same -- you CANNOT just dump in a certain amount and forget about it, especially with aftermarket springs. The LEVELS must be set correctly, and within 1mm of each other.

Then order up Progressive shocks and springs for the back and enjoy...

Just to add that the forks are pressed down when measuring the oil level. don't try to extend them and make sure they are all the way down. I jiggled the springs a little to make sure they were set.

Springs in, straight up in the air ( a vise with wooden pads works great) fill slowly until you get the right amount in each tube. I use a turkey baster to remove excess,.

[gspaul]

I'm not going to your house for thank's giving!

[duaneage]

Considering the distinctly American nature of the holiday I would not expect an Aussie to know what the secret ingredient in the stuffing is. Besides there are probably a few GSers that use fork oil for gravy once in a while.

:P

[bwringer]

Just to add that the forks are pressed down when measuring the oil level. don't try to extend them and make sure they are all the way down. I jiggled the springs a little to make sure they were set.

Springs in, straight up in the air ( a vise with wooden pads works great) fill slowly until you get the right amount in each tube. I use a turkey baster to remove excess,.

Duanage, you're half right, and I think I was all wrong at first.

According to my manuals for this exact bike (a fine example of which is in my garage), you measure the fork oil level with the forks fully compressed and the springs OUT. With the fork leg level, the spec is should be 140mm from the top of the fork tube. (Please note that L model forks are different. We are only talking about the 1983 GS850G.)

Since my garage is not built on a slope and I don't want to remove the fork legs just to check the freaking oil levels, I cheat and measure the level from the midpoint. I slide my measuring doodad around the edge of the fork tube until I'm all the way to the left or right and halfway between the front and back. If you picture the surface of the fluid, this will make sense.

The actual levels of the fluid don't matter a great deal a few mm one way or the other. What matters is that they are exactly the SAME, so fork action is the same on both sides and binding is minimized.

I corrected my post above. And I would definitely suggest working with a good manual (I have both Clymer and Haynes) rather than trusting too much in the fallible memories of us GSR users!

[bwringer]

After reading all the excellent replies, you may be excused if you're confused. First thing you need to do is find out if you have air forks. Got a Schraeder valve in the fork cap? Air forks have a spring in them but its only there to keep the forks from compressing fully if you lose air. If your seals are gone, the air will also be gone. Once you know what you have, check the manual, service the seals and fork oil, and go with the advice already given. And believe me when I tell you-ten minutes with the manual MAY save you a lot more time when you start the job - not to mention buggered parts, etc. Don't ask how I know this :roll: Cheers!

This bike has an air fitting on the left side of the fork that feeds both fork tubes via a hose. However, for the reasons stated above, I feel that it's a very bad idea to use air pressure in the forks on an old bike. It's just not a very reliable system, and the consequences of poor front suspension action (gradual or sudden loss of air pressure, uneven air pressure) can be dire.

If you need more preload, you must first replace the sagging antique original springs. Then add preload the right way, with spacers. Experiment with different lengths to arrive at the correct solution for your bike and riding.