1989 gsxr 1100 fork adjustment

[gsBert]

hi, i'm stumped because i know nothing and was given the bike that way right after it was assembled...

my 81 gs has a 89 gsxr 1100 front end and it dives MASSIVELY under braking. actually pulling the front brake does 2 things separated by a split second: rapidly compress the forks and lock up the wheel.

i can deal with the wheel locking (just got to get used to better brakes than my 1150 front end on the other bike), but my fender hits my oil cooler and i really hate all that dive... and i guess if the front end didnt drop so fast i could transfer weight forward more gradually and avoid the lockup...

the forks work very well over bumps but the braking bit really sucks and is unsafe, i mean forget about a panic stop, any attempt is an instant lockup (as proven by a friend who dropped the bike after 50 meters of riding it).

now i think i know those forks are adjustable for preload, compression and rebound, but then again, what do i know?

on the bottom i got a few screws, i know i can find the one that holds the wheel on, another will drain the oil i guess and the last one is for some adjustment (compression or rebound?) and WHERE IS IT?

on the top i have a big nut which i guess holds the stuff together so i probably shouldnt mess with it.
i also have a slotted adjuster (looks like it will fit a 25mm wrench but i havent tried yet)
and then there's a screw that seems to be inviting my flat driver/prybar.
which adjuster does what?

i'm guessing that in my case i'd want to set the preload and compression at their stiffest. rebound seems fine as it is, but i'll have to see with the stiffer compression, and i really dont mind my front end getting airborne, im used to it with the other bike...

so, anyone know these forks?and what do i turn which way to fix my problem?

my best guess is mess with the top controls and screw them in all the way but i'd really like some advice...

thanks

[robinjo]

Your bike is a fair bit heavier then the donor bike which the forks came off so I would as a first uprate the spring rate from stock be it linear or progressive. Also it could be that your set of forks does not have all three adjustments but only rebound or compression damping which I think is at the bottom of the forks under the calipers :? and preload (which has nothing to do with spring rate but with the amount of sag). If you do not get a definitive answer ask the question at www.oldskoolsuzuki.info .

[Billy Ricks]

Bert,

On top of each fork tube you will find and brass, slotted screw inside of the preload adjusters. The preload adjusters are the cylinder shaped parts coming out of the fork caps. They have flat sides machined into the top edge of them. You fit a wrench to those flat sides to turn that part to adjust preload. Clockwise stiffens preload and counter lightens preload. They have rings cut around them for preload adjustment reference.

The first thing you want to do is set up the sag on your bike. That involves getting the front wheel off the ground and measuring the length of the fork. Measure from the bottom of the lower triple to the fork seals. Then put the bike on the ground with your weight in the seat. Measure that distance again. Subract the second measurement from the first and that's your sag. You will want something between 1 - 1 1/4". You need to set the rear suspension up as close to the front as possible.

You have both rebound and compression adjustment on your fork. The ones on top that are located inside the preload adjusters are your rebound dampers. I don't remember off the top of my head how many clicks of adjustment there are. If there are say 12 then start off on maybe the 7th or 8th click. Counter-clockwise is the lowest number both for compression and rebound.

The compression adjusters are at the bottom rear of the fork legs. For compression damping if you have 12 clicks as an arbitrary number then start with about 4 or 5 clicks of compression damping.

You want the fork to be able to use almost all of it's travel on what you consider the very worst bump or pothole you ever hit. With sag set properly you can get away with lighter compression damping. You use a little more rebound damping so the bike will just settle back into it's normal attitude with no pogo effect from not enough rebound damping. Use only as much damping as it takes to get the job done. You want to let the spring work for you.

[gsBert]

yeah well, playing with any of the adjusters did nothing (and yeah i have all 3 settings adjustable, thanks for the excellently detailed reply billy)

all i get when i ever so lightly squeeze the front brake is a clunk and very rapid dive followed by squished nuts and a locked front wheel. how do i check if i have oil in there? am i missing oil? should my forks clunk?

[Billy Ricks]

Bert,
Check your "all forked up" thread.