1982 GS1100G 37 mm fork oil weight and volume.

[Steve]

held vertically? you've got to be kidding....

Since the proper way to do this involves removing the fork tube from the bike, it's really rather easy to hold it vertically.

I will second bwringer's recommendation on Sonic springs and 10w oil. Since the 850 is a few pounds heavier than your 1100, and I have added a bunch more weight to the front (frame-mounted fairing), I also went with the 1.1 rate springs. Brian (bwringer) needs the stiffer springs due to riding style, I need them for the additional weight on the bike. The 10w oil is great.

I also agree that it is the LEVEL that is more important than the amount. Some will say that the level needs to be within 1mm or so from side to side, I'm not so sure it needs to be quite that precise, but certainly as close as you can get them.

.

[derwood]

(with springs out and fork leg collapsed all the way and held vertically) is the GS standard.

held vertically? you've got to be kidding....

[bwringer]

I'm a speedy galoot, and I use Sonic springs (1.1 rate to match my, er, mass) with 10W fork oil.

I found that once I had proper springs in there, I didn't need the 15W fork oil to keep things controlled. 10W gives much better feel and handling, not to mention a less harsh ride.

Also, the AMOUNT of fork oil is mostly irrelevant. You need to set the fork oil LEVEL correctly, and set it the same on both sides. 140mm from the top (with springs out and fork leg collapsed all the way and held vertically) is the GS standard. Overfill a bit, pump a while to get all the air bubbles out, then use a large syringe with a measured piece of tubing to slurp out oil to the correct level.

The Sonic springs really make a huge difference over the limp "one size fits all" Progressives. Even just putt-putting around, you notice a lot less brake dive and much improved handling.

Great info and thanks for the links. Long 4th weekend and now I can do all the fluids and some other maintenance( thanks again for link to manuals). The Sonic's spring rate calculator helped a lot, would not have had a clue and would have had to call. Going to try the fresh oil and cutting a couple lengths of pvc over stock spacer in 1/2" increments. See what the weekend shows. For $85 it is a ez jump to fix a scary front suspension. Think I will try a set of their springs in one of the rd's. I thrash those little two strokes and have been running progressives in them for years.

[hikermikem]

According to my OEM manual:

Volume in each fork leg - 255 ml (8.62 US oz)
15 weight oil
air pressure - 0.6 kg/cm2 (8.5 psi)

You can replace the stock spacer with a longer piece of PVC pipe to stiffen up the front, but the stock front suspension is pretty soft anyway...

I don't use air because it will push the oil past the fork seal if it's too much pressure (which is easy to do).

I agree with mmattockx to replace the stock springs with straight rate Sonic ones. Get the correct rate for your weight & riding style and you will notice a big difference. I have used the progressives as well & didn't think they made that much of a difference on these big heavy bikes...

http://sonicsprings.com/catalog/index.php

[mmattockx]

Stock springs or what was in the new to me 35 year old bike. 37k miles . May up grade to proggressives and dive in deeper, if fresh oil dosn't slow things down. No manual came with bike, as said got a clymer on order. Need volume in fluid ounces or ml. . Got a most of a qt of spectra 15w left from doing a friends goldwings forks.

If you are looking at Progressive Suspension springs then do it right and get Sonic or Race Tech straight rate springs in the correct rate (I recommend the Sonic springs myself). The 15W will be OK if you want to confirm that your fork springs are shot (I assure they are). Download a service manual here: http://members.dslextreme.com/users/bikecliff/


Mark

Stock springs or what was in the new to me 35 year old bike. 37k miles . May up grade to proggressives and dive in deeper, if fresh oil dosn't slow things down. No manual came with bike, as said got a clymer on order. Need volume in fluid ounces or ml. . Got a most of a qt of spectra 15w left from doing a friends goldwings forks.

[mmattockx]

Stock fork springs or aftermarket? I would say 10W for stock springs, can't say on the height/volume if you are using air assist. What does your service manual say for stock volume?


Mark

[Mosquito13]

Tried the search tool but two wordings and three pages deep on each search did not turn up info. Drained with top air caps off over night. Before doing that they held air at 12lb for 24 hours , so i am comfortable that the seals are good. Need to know the weight and volume of fork oil to add. Ordered a manual but it will not be here till after the weekend.