BMW R80 G/S Fork setings ?

[Beemerboff]

50 mm front rider sag is just about perfect, but only if you have the rear sag within 6/10 mm less.

So set the rear sag to 40/44 and try that.

But for a suspension spring to work best you want it to have between 15 and 20 mm preload on the spring .

And, simply ,if you dont have the correct preload at the sag you want you have the wrong spring and you should change it.

Then when the springs are correct , fine tune the balance, front to rear.

By trial and error, there is no other way.

You can do that at either end , whichever is the easiest for you to do.

[SOLO LOBO]

Originally Posted by batoutoflahonda

I've put .85 weight straight wound Race Tech springs in. Hardly any preload. filled to about 6" from the top of the fork.

2 Q's?

How much did the raceteck springs run ya?

it that 6" from the top, forks fully extended, springs in?

[Caddy82rats]

Originally Posted by batoutoflahonda

No. It's a R80G/S standard. It started here:

http://www.advrider.com/forums/showt...ight=race+tech

Lots to read. The meat of it starts around post 90.

Also this explains things really well:

http://www.sportrider.com/tech/146_9502_tech/index.html

Great reading thanks

[batoutoflahonda]

Originally Posted by SOLO LOBO

2 Q's?

How much did the raceteck springs run ya?

it that 6" from the top, forks fully extended, springs in?

I think they were like $100.00, the fork oil I think is 180mm from the top of the caps, forks compressed with the gold valve and 1/2 inch spacer (takes up volume in the fork) in and no springs. The fluid amount comes to 325 ml +/- 25ml. per leg. This seem to be the most fluid you can put in without running into hydraulic lock. It took 275mm just to cover the GV/spacer.

A note though on the springs. They are 5" shorter than the stock spring. I had to measure the length of the protrusion of the fork cap into the fork, and cut the PVC pipe +5mm (just to keep things from flopping around) to just touch the bottom of the fork cap. Problem is, you can't lessen the preload on the spring any more and with a half tank of gas in the PD tank, me on it, the sag right at the limit on the firm side at 22mm over static (50mm overall). I think if I had to do it again I would call around and find spring comparable to the Race Tech .85(maybe Worth or some one), that was a bit longer.

I was having issues with the GV on high speed compression. So I took all the preload out of the spring because I had heard it was originally made for a Harley which out weighs the G/S.

You know, we should just get together and you can ride it. If you like, we can set yours up to match.

Now if I could just sort out that Wiber's shock (ugh!).

[SOLO LOBO]

Originally Posted by batoutoflahonda

The fluid amount comes to 325 ml +/- 25ml. per leg. This seem to be the most fluid you can put in without running into hydraulic lock. It took 275mm just to cover the GV/spacer.

Thanks! I'm going to measure my sag this weekend and put in a shortened stock springs if required....

I think the R100GS reacetech is harley, ours is RZ350

Originally Posted by batoutoflahonda

You know, we should just get together and you can ride it. If you like, we can set yours up to match.

not a bad idea

[batoutoflahonda]

Probably the better way to go. With the RT spring being short, the spacer is so long I think it takes up all the space between the triple clamps and I have no idea what the spring will compress down to. Meaning I may have lost some travel. But....I was looking to get rid of that wallowing in corners and handle bad dirt roads as a touring machine, which it does great now. For folks looking to do dual sport enduro stuff, these springs probably aren't the way to go because of the unknown travel.

[Caddy82rats]

I've tried WP springs with 7,5W oil, good compromise for offroad and road

[batoutoflahonda]

Originally Posted by Caddy82rats

I've tried WP springs with 7,5W oil, good compromise for offroad and road

Did you have to use a spacer? What is the spring rate?

Sort of an update. I've turned the gold valve spring preload all the way out, meaning the nut is just touching the spring. I read some where that the GV we are using was originally designed for a Harley. Which I'm sure out weighs the the G/S.

Any way, it's works great now. I feel no jolts through the bar and it runs over washboard like it's fresh tar. Corners as if on rails. I'll admit though, now that it's warmed up, it may a bit on the soft side.

So:
It's 1981 R80G/S with a PD tank.
My weight: 180 in full gear
.85wt Race tech springs/no preload
Amsoil 10wt oil, filled to 160mm (ish) from the fork top, (fork compressed, no spring) note: going to try Moble 1 syn ATF again as I did think it worked really well.
Race Tech Gold valve, blue spring (.40wt) no preload with 1/2" spacer at base (fabricated from schedule 20 PVC electrical conduit. The wall is thicker and if the edge is carefully chamfered it 'snaps' on the end of the GV)
Wilbers Rear Shock

Hope this info helps as a base line for some one. It took 3 months of experimenting, at least 4 oil changes to get the wt I liked. And 3 more changes to get the volume I liked, plus changing the GV settings. The bike is set up for running fire and unimproved dirt roads, corner well and be nice to tour on. It is not set up to run single track at race speeds, jump, or do back flips (maybe later)....stay tuned.

PS
It will handle g-outs/inverse cut water bars at 30mph or so with no issues & track straight. But uphill large steps, 3-4 footers, it does tend to drive the front down and rebound really quick. I attribute this the weight of the bike and perhaps speed. But, just be prepared for a light front if you try that kind of stuff.

[Caddy82rats]

When i've dismanteled the fork i've find a kind of aloy spacer between tube and aloy leg (around 1cm thickness)
On WP manual they say :
Part number 9932.0205.A
Oil : SAE 10 (They send me 7.5) Without any coment
Air chamber 140mm
And... BMW F800S 06> (so I presume thos springs are for F800 GS)
But they do the trick
springs had the same size than BMW but steel string seems larger
I've use no spacer

Hope this help some

[Rob Farmer]

Originally Posted by batoutoflahonda

Now if I could just sort out that Wiber's shock (ugh!).

I'm not happy with my wilbers shock either. I've set it up exactly as the instructions suggest and have the static and dynamic sag correct but it still feels as though I'm being kicked up the backside when I ride over anything bigger than a matchstick. There's far to much compression damping, unfortunatly the shock I bought doesn't have adjustable compression damping so I'm stuck with it at the minute.

I really don't want to fit the Racetechs until I get the back end sorted out.

[Rob Farmer]

Originally Posted by Caddy82rats

When i've dismanteled the fork i've find a kind of aloy spacer between tube and aloy leg (around 1cm thickness)

The spacer simply lifts the front end slightly.

I took these measurements off my bike. it's fitted with the original fork springs

Front wheel off floor (Measurement A)= 228mm
Bikes own weight (Measurement B) = 195mm
Me on Bike (Measurement C) = 175 mm

This gives Static Sag (A-B) = 33mm
Dynamic Sag (A-C) = 53mm

Total travel at front = 26.5% which isn't enough according to the Wilbers sheet.

[Caddy82rats]

Yep for the spacer
I've around between 4 and 5cm dynamic sag on my G/S

[Caddy82rats]

Originally Posted by Rob Farmer

I'm not happy with my wilbers shock either. I've set it up exactly as the instructions suggest and have the static and dynamic sag correct but it still feels as though I'm being kicked up the backside when I ride over anything bigger than a matchstick. There's far to much compression damping, unfortunatly the shock I bought doesn't have adjustable compression damping so I'm stuck with it at the minute.

I really don't want to fit the Racetechs until I get the back end sorted out.

I've big dificulties to setup my Ohlins...
Maybe he need a rebuild
Rebund (lower knob), I can feel the first 5 clics, after that I've to imagine them. Someone here had told this is a sign of no gas in the shock

[batoutoflahonda]

Originally Posted by Rob Farmer

I'm not happy with my wilbers shock either. I've set it up exactly as the instructions suggest and have the static and dynamic sag correct but it still feels as though I'm being kicked up the backside when I ride over anything bigger than a matchstick. There's far to much compression damping, unfortunatly the shock I bought doesn't have adjustable compression damping so I'm stuck with it at the minute.

I really don't want to fit the Racetechs until I get the back end sorted out.

Dude, I so hear yah. Thing is the spring rate feels ok, but it just has no give. but, I did load it up with a ton of camping gear on a 3,000 mile road trip and oddly enough, it feels a lot better now. So I'm not sure what to do now. I might send it back down to Ted Porter over the winter, or see if they will let me try a different spring if I can return it if it no work.. I can still feel it rebounding and compressing the forks.

But I agree. I've turned the rebound all the way out just to get to work off road.

[SOLO LOBO]

Hate to tell you this guys but my Ohlins absolutely kicks ass... from solo to loaded for 4 days of off-road and camping with all the gear riding pave, gravel and over 4 foot tall berms it was solid, predictable, forgiving and simply right on the money...

That $600+ seems like a good investment now...