Fork Oil Capicity Discrepency On '82 GS850GL ?

[joejeweler]

Hi all,......today i finally got around to changing the front fork oil on my '82 GS850GL. Although my seals weren't leaking and the forks seemed pretty good at damping,.... the dark color of the old oil made it very clear this item had been negletted by the previous owners and needed changing.

I cheated a bit and just removed the air adjust valve from the top of the fork (rather than removing the handelbars and the main top fork cover as per the Clymer manual), and then drained each fork separately and measured the result,........looked exactly like 8 US ounces had been in each fork. I then sat on the bike and compressed the front suspension to remove any remaining few drops and replaced the drain screws.

BUT,......when checking both the Clymer and Hayne's service manual for this bike,........they both state the capacity of the front fork oil as 302CC, or 10.2 US ounces.

However,......the Suzuki Owners Manual i recieved with the bike, (for the GS850GL), printed in June 1981,......state the proper front fork oil capacity as just 245cc, or 8.2 US ounces. I know fork oil levels can be critical, so i want to get it right.

The Clymer manual stated the maximum allowable oil level variation between forks as just 1 mm, if measured the usual way with the top off the fork tube and usuing a rule. My "cheating" method doesn't allow you to see the oil level directly,......so i took great care in measuring the amount of added oil.

The fact that i removed just 8 ounces from each tube has me wondering if that was the proper fill amount per owner's manual,.....or if over the many years some oil had been depleated thru use and the Owner's Manual is wrong.

Here's what i did to complete the fill operation (i used PJ 10 weight "Gold" premium fork oil). I picked up an attachment normally used to pour transmission or gear oil,......and this screws onto the oil bottle top with a clear tube with a plastic tip on the end that fits perfectly into the air valve mounting hole once the entire valve is removed. (you have to hold it there with a little hand pressure).

It's then a simple matter to press the tip into the hole, lift the oil bottle up to fill the clear tube with oil,.......and then pinch the oil bottle to push the oil thru the fairly small opening leading into the actual tube.

I checked the level leaving the bottle often and when it reached 10 ounces on each fork tube i stopped. Then replaced the air valve assembly and used a hand pump to add 15 lbs of air pressure to the forks.

I took it out for a test drive,.......and the front suspension "felt" great! The forks seemed more responsive to even the lighest bumps in the road,.......possibly the low 10 weight oil was responsible for this feel but i liked it alot. I found myself searching out even a few bigger bumps and very smooth running over even these.

The 10 ounces in each fork doesn't seem to be causing any problems such as leaks,........but the variations in recommended capacities has me wondering which is right. Seems unlikely both the Haynes AND Clymer got it wrong,.......but geeze,......you'd think the actual Owner's Manual would be believable also.

I went with the 10 ounce "test" figuring it would be easier to just remove a few onces if problems developed.

Anyway,......i figured that since many of you own this bike and have changed your own fork oil, what amount of oil do you use on the GS850GL,...........8.28oz as per Owner's Manual,.......or 10.21 oz as per Clymer and Haynes?

[ptm]

According to the Suzuki factory service manual, the '82 GS850GL should have "245 ml (8.27 US oz) in each leg".

I wouldn't worry as much about getting exactly the right amount in them as long as they are the same. If you carefully use the same technique to fill both they should be fine.

The other (and better) way to measure the correct amount is to measure the distance from the top of the inner tube to the top of the oil. For the '82 GS850GL, that distance should be 260 mm or 10.2 in. The forks have to be removed form the bike and positioned vertically without the spring and with the inner tube fully inserted in the outer fork housing.

One other thing. If the oil was really old and dirty, after draining the oil, you should flush the system out with kerosene several times, pumping the fork to flush it completely, until it comes out clean, then let it dry before adding the new oil.

It's a good winter job...

[joejeweler]

Thanks for the info about the kerosene and the actual Suzuki service manual specs. Still seems strange BOTH Clymer and Haynes got it wrong,......with the same figure no less.

I was going to run the bike with the curent fresh fork oil only a short while and change it again anyway,........figuring that would get any remaining residue out. Depending on how it looks i might do the kero also,.......but then i would feel the need to use another tempory oil flush change before the final change in order to get any remaing kero out.

Whatever i decide i will at least drop the levels to the 8.3 ounce level for the "permanent" change.

[ptm]

I wonder if they confused the 10.2 inch measurement for the level with the 10.2 oz capacity...

If you leave the drain plugs out overnight it should drain out/dry out enough of the kerosene. Obviously the best way is to remove the forks and disassemble them - then you can really get in there and clean out all the muck.