What forks have I got - Gs850 ?

[Brendan W]

Could some kind person enlighten me as to the possible identity of the forks on my 1981 850. I suspect that they are not the original somehow. Sorry for the poor quality picture but it tries to show a round rubber cover on a 22mm hex fork cap which has a hole down the middle with a slotted head about part about 12mm down.

[Agemax]

they are the adjustable preload fork tops from an 1100 katana, and possibly other models.
it does not mean you have katana forks as those tops fit in any 37mm diameter forks.

do you have the anti dive units on the bottom of the fork legs?

[Brendan W]

No anti-dive units. Have no complaints about the front and the PO ( one of them anyway) seems to have looked after the bike. What's the most likely scenario , just used those caps with original springs or used KAT springs and spacers? If I wanted to change out the oil what should I use as a guide for the amount?
Thanks for looking.

[Agemax]

i would guess at just swapped the fork tops. they may be stock for that model, i do not know but somebody will be along soon who knows for sure.

just use the oil quantity required for your models forks.

[postman_pat]

In theory, an '81 GS850 should have fork caps with an air valve. But, it's a 30-year-old bike and these bikes go through a lot of mods in that time. A previous owner looks to have swapped the fork cap bolts on yours. As Agemax says, it doesn't affect the amount of oil you should use - just use the standard recommended amount for the 850.

[Brendan W]

Thanks guys. Think I'll open it up and have a look at what's going on in there. I'd like to measure the springs and change the fluid. Do you back off the adjuster fully before removing the cap and is it just a screwdriver job? Can't find anything on how to use these type of caps.

[bwringer]

The adjuster is just a ramped collar with detents for three steps of preload; it isn't threaded. You don't need to back off the preload to remove the caps. Personally, I would remove the caps and make sure everything is moving freely and use a bit of grease before attempting to move the adjusters.

Without pics of the rest of the forks and some measurements, there's no way to tell what you have. It is certainly possible that someone installed the preload caps from an 1100E into the stock non-adjustable forks.

Show us some pics of the forks, and take a reasonably precise center-to-center measurement in millimeters between the fork legs. (It will be something like 185mm or 195mm, I think.)

Also, please clarify whether you have a GS850G or GS850GL.

[Brendan W]

It's an '81 GS850GX and the fork centre separation is 185mm . The adjusters look like slot head screws. Can't see anything that might be reference marks. One of them has the slot aligned at one o'clock and the other one at two o'clock

Thanks for looking - hopefully my photography is improving as well.

time to update my sig

[Brendan W]

OK just an update. Figured out the adjuster thing - sometimes just asking the question helps get the grey cells into first gear. Springs are progressive and approx 476mm long each side. Service manual gives 416mm free length so it looks like I've inherited different springs as well as adjusters. Both preload adjusters set at two or B, Took 250 cc from the left fork and about 150cc from the right which has the slight suggestion of a seal leak. Less said about the drain screws the better and I won't even try to describe the colour of the old fluid. Refilled and set preloads to three or C.
What a transformation. This bike just keeps getting better and better. I had been a bit concerned about jerkiness rolling on throttle in slow bends and was putting it down to all sorts of imagined things but now the front is like a rock.
I think I'm slowly starting to realise the true meaning of the advice to take nothing for granted on a 30 year old cycle.

[850 Combat]

Your chrome front fender didn't come on an '81 either.

[Brendan W]

The front master cylinder reservoir is the older round type. Starting to think Johnny Cash assembled this bike.

[postman_pat]

The front master cylinder reservoir is the older round type. Starting to think Johnny Cash assembled this bike.

Sometimes, Suzuki GS bikes can be compared to the old tale of the farmer’s axe (even though everything’s been replaced over time, it’s still the same axe).

[Brendan W]

So starting to get around to suspension setup. The front compresses 32mm/1"1/4 between wheel off the floor to bike weight only on the springs. I have non stock springs with a four position ramp adjuster - I'm on three.
32mm seems a lot to me and the last ramp won't take it back so much. I'm thinking I need a spacer of about 15mm. Any opinions warmly welcomed

[Steve]

My opinion (you asked for it ) is that you need to use the proper measurement.

Measure the distance from the top of the fork to the bottom of the lower triple clamp while the bike is on the centerstand. Have a helper make the same measurement with both wheels on the ground and you sitting on the bike. Try to put all of your weight on the bike, just balancing with your tippy-toes. The difference of those two measurements is your "sag". The recommended amount of "sag" is 20-25% of total travel. Most of our forks have 5-6 inches of travel, so you are looking for about 1 to 1 1/2 inches of "sag" when you are on the bike. The length of any spacer you need to add will be the difference between your actual measurement and what you want. If you find that you drop 2 1/4 inches, add a 1-inch spacer, it will take you up to 1 1/4 inches, etc.

.

[Brendan W]

Thanks for that. Back of the envelope I reckon my weight will increase the drop to 1"3/4 total so I'm looking at 1/2". Will wait 'till other half returns for help on the actual measurement.
What are people using for spacer material - have seen references to pvc tubing