suspension: rear shock adjust

[mixelpix]

Uhhh, so - how exactly does one adjust the spring load setting on the rear shocks? Is there a tool I am missing or something?

I'm about 5'10', 190lbs, and I ride a 1980 xs1100 LG and I sometimes ride with a tank bag on the front, but mostly am a single rider. Any advice on how to approach suspension settings would be greatly appreciated.

I currently have the damping set to "one" on both rear shocks, but I wanted to adjust the spring action and... well, see if I could even notice any difference. The front forks are originals and could prolly stand new springs, but otherwise the fluid is recently changed, seals good and the air pressure set to 14lbs on both.

Thanks!

-Patrick Kennedy

[webbcraft2150]

There is a tool that was included in the tool kit to adjust the rear shcoks. Since most of these are long gone, you can use a pair of channel locks to adjust them. I will put a rag around the adjustment ring, clamp the channel locks on em and turn. If you give the adjustment ring a quick shot of WD40 and let it soak in, they turn a whole lot easier.

[Jerry]

Just a note...17psi is the Max pressure for Yamaha's XS and XJ front forks. If you are running 14 psi, I would recommend you replace the front springs soon. Look at progressive wound springs from Progressive and Hagon. With the right preload you may not need to run any air in the front, or very low pressures. (Many who have made this conversion, including me, don't use any air pressure.) Remember, the air pressure only sets the initial force needed to compress the forks, it does not change the spring rate, damping, or rebound rates. 14 psi is a high setting for "normal" riding.

[TopCatGr58]

Hey Patrick,

Along the same lines as what Jerry said about the front, the rear spring adjuster is merely just a height adjustment, it doesn't really do anything to the spring rate. It just sets the ride higher so if you are loading saddlebags and such fairly heavy, it can help prevent the bottoming out affect. The dampener setting is what will possibly provide a variance in your ride, but after 20 years, you'll be lucky if it does anything!
T.C.

[motoman]

What Webb said for adjusting is the simplest way, and raising spring adjustment up will reduce overall shock travel by that much as the spring windings are closer together. Doesn't change height of bike, but will compress less with rider aboard. The 14psi in front of that bike is a bit high for one-up. The air in front does affect dampening rate(speed at which they compress). The was a trick for us old moto-crossers, by drilling and tapping fork caps and installin a schrader valve, and running 5-7psi in front forks to slow down travel rate(to avoid bottoming of the then lesser travel forks), and to get a faster rebound to better meet and have full travel in successive whoops. The sinerio is somewhat different with our street bikes. We're looking for a more slower over-all reaction up front. My full dress Venturer with original stock front tubes and springs likes 14psi up front and rear spring rate on 3 and dampener on 3 or 4 if it's a road with several dips as alot of two lane roads have. Long interstate riding, or around town one-up it likes 7-9psi front and rear spring rate on second notch from bottom and dampening on 2 or 3 if I have baggage, etc. in trunks. This bike weighs in at 680lbs.+- 10lbs. depending on fuel level. I'm 5'10" and 180lbs. Hope that gives you a reference and starting point.

[fxrer]

At the bottom of the shock is a ½” protruding cylinder with a hole in it. The original “tool” in the kit is nothing more than a shaft, about 3/16” (5 mm) dia which fits into that hole. You can use any similar shaft (Phillips screw driver, drift punch, etc) that fits snug. Insert it into the hole and use that to turn the shock to adjust spring pre-load. As noted, using WD40 or other lube makes it easier to turn.

As for front forks, the owner’s manual for my ’80 SG specifies a MAX air pressure of 36 psi, minimum 6 psi, with no more than 1.5 psi difference between forks

[Jerry]

36 PSI in the front forks? Well, I've never had an '80 model, but sounds high to me. Below is the Yamaha spec for the XJ air forks:



Minimum is 5.7 psi, not far from the 6 psi mentioned for the SG, but max is only 17 psi. I was under the impression that all Yamaha air forks had the same basic specs, but have been wrong before!

[mixelpix]

whoa!

Originally posted by Jerry
Just a note...17psi is the Max pressure for Yamaha's XS and XJ front forks. If you are running 14 psi, I would recommend you replace the front springs soon.

thanks everyone for all the info! I really had no idea how to approach my thinking about suspension - this is great.

I think I got the 14psi setting out of the owners manual. maybe it was a chiltons...

I see most air pumps with psi gauges which are around 20-100+ psi.

Can someone recommend an air pump which can be set for a lower scale? I don't think I could set something to 5.7psi if I tried - I have a manual bicycle pump and a small air compressor.

Any recs on replacement fork springs? I'll look into the archives and ask at my local bikeshop - btw a great one just opened up down the road from me in Oakland, CA, "Godspeed" - good crew over there.

check out Godspeed

Thanks again!

[mixelpix]

Originally posted by webbcraft2150
There is a tool that was included in the tool kit to adjust the rear shcoks. Since most of these are long gone, you can use a pair of channel locks to adjust them. I will put a rag around the adjustment ring, clamp the channel locks on em and turn. If you give the adjustment ring a quick shot of WD40 and let it soak in, they turn a whole lot easier.

Hmm. I have the original toolkit - is that the tool which is kind of a crescent on the end? I'm not sure how to use it, or what a pair of channel locks are. Is there anything special to it, or do I just need to use a little more elbow grease?

Thanks Again!

[John]

The tool with the cresent sounds like the spanner wrench needed to set the spring preload.

[mixelpix]

Originally posted by John
The tool with the cresent sounds like the spanner wrench needed to set the spring preload.

Thanks, I'll give it a try tonight when I get home from werk. -pdk

[motoman]

fxrer is correct on that Jerry, and mixel, a small air compressor is fine, just a quick one second shot, then check. Most likely be over, keep checking with gauge as you will loose 2-5psi with every check. You'll understand all that just as soon as you follow that procedure.

[webbcraft2150]

Be real careful using a air compressor to fill your forks unless you can regulate it down to about 20psi. At 125psi it takes about a nano second to blow a fork seal

[motoman]

Nano-nano to that Webbcraft!.......Thanks for adding that word of caution.......

[mixelpix]

Originally posted by webbcraft2150
Be real careful using a air compressor to fill your forks unless you can regulate it down to about 20psi.

Could you reccomend a brand/model? Thanks!