SG front spring

[jetmechmarty]

I can't find my manual and Bug's book appears to cover only the standard.

What is the free length of the front springs on the SG? All I have is discard if less than 24.1 in.

Thanx!

[TopCatGr58]

Hey Marty,

The unsprung length specs shows 612.2 mm, or 24.10", so discarding it if it's a LITTLE less than that I would think to be extreme??? You might get by with a spacer??

If you decide to go with Progressives, they only make 1 size/length for the XS, and you'll need to put in a ~4" spacer... the standard spring is
516mm or 20.31" !

If you think that's bad, I've got 4" over's on my special, and already have a 4"
spacer, but if I got to Progressives, I'll need an 8" spacer!

HTH?!
T.C.

[jetmechmarty]

Thanx TC!

My springs are sacked. I have 50 mm of sag and I'm looking for half of that. I have decided to have springs custom wound at Traxxion Dynamics as they come highly recommended and they're local. They promise perfection and all I'll have to do is drop them in for about the same money as the Progressives. I'll report back on how that goes. They tell me they can make them from the old springs. Mine are no longer 24".

[TopCatGr58]

Hey Marty,

Some of the pages I saw also had specific spring rates for the stock springs at different points of compression. Would you want/need that info also? Are they going to be making variable rate springs? Aside from shipping fees, that sounds like it might be a more viable option for me as well, vs. having to use 8" spacers! Mine also has a fair amount of braking DIVE as well, but I think I tried a bit of air pressure in mine, but that seemed to make it too stiff. I can't recall if I've tried a thicker fork oil yet. Also you have the emulators in yours, so not sure how much performance enhancement I can expect from just the springs vs. having to put in the emulators as well!

T.C.

[jetmechmarty]

TC et al,

I'm going to straight rate springs. They said to bring them the forks, then said they could do them off the old springs. I also have the specs from Bug's service manuals, but the length was missing for the Special. It appears they need my weight, how I ride, and info on the bike. I know what it weighs, but not how the weight is distributed.

One of the Senior Technical Advisors at XS650 Garage recommended them, and I trust his judgement. He told my Traxxion made his springs with too little sag and they made him a new set at no charge, no shipping, no hassle. They made it right. I think you can get recommendations from them on the extended forks.

The RaceTech emulators took out the sudden dive. I still get too much compression with the sacked springs, but I was impressed with the difference it made. I haven't tried to tune them yet. Since I paid the price of admission, I'll call RaceTech for help with that after the spring situation is fixed.

I put the 120/170 Progressive shocks on the back and took a ride before emulator installation. I had my daughter on the pillion. We went around a fast turn and my foot was pinned between the pavement and the shift lever. The emulators and max preload out back made that issue go away. It still isn't right, but I feel it's getting close to where I want it. I want to carve corners without throwing sparks.

TC, I believe thicker oil will slow the rebound. That may be desirable. At least, that is the case with the emulators. RaceTech says to tune the rebound with viscosity.

[TopCatGr58]

Marty,

I was perusing the Axxion site, and saw on their Spring Rate chart that for a bike and rider weight combo of 700lbs or more, that the chart recommended a spring rate of ~1kg/mm.

Surprisingly, the book/manual for the SG showed a variable spring rate dependent on the distance the spring/fork travels...for the first ~4 inches of the 7 inch max travel, the rate is about 0.43kg/mm, and for the last 3 inches, it was only up to 0.6 kg/mm, and so both of those are almost 1/2 the stiffness of the Axxion springs according to their suggestion chart!!

Just an FYI regarding the sag and dive of the XS front forks and stock springs!
T.C.

[jetmechmarty]

I pulled my springs. I believe them to be stock. They ARE progressive wound, just as you have pointed out. I don't think much of it at this point.

Where is the chart you're reading? I want to see it.

[jetmechmarty]

I got the following at XS650 Garage:

When Traxxion made springs for my D a few years back that's all I gave 'em and all they needed; their formula told them .90 kg./mm. rate. That sounded stiff; unlike some sport bikes, the old XS doesn't put 55% of its weight in the nose! But they promised to make it right if the .90's didn't work out. Sure enough, those springs yielded 12 mm. of laden sag, with zero preload. The guys at Traxxion were as good as their word; they had a pair of .80's wound, let me ride on the .90's until the new springs arrived, and covered the extra shipping themselves. I couldn't have asked for better service.

What is the SG length of travel?

First look at the rated travel of your fork (T). The variables are proposed free length (L), wire diameter (W), coil count at proposed free length (C), preload (P), and travel to coil bind (B). Here's the formula: B=L-(WxC)-P. If B=/>T, you're good to go. If B<T, L will result in coil bind; recalculate at a greater length and coil count.

[jetmechmarty]

Never mind. I found the chart and reread the post. 7 inches of travel. I should be able to get it dialed in now.

[Poprock]

Thicker oil may not yield the results you want. I ran 15 w. oil for a while. Harsh ride, still got brake dive. Replaced the 15 w. with ATF and the ride smoothed out wonderfully. Brake dive didn't increase. Heavy oil will hydro-lock. Bob Jones recommended drilling a couple more holes in something in the bottom of the shock. Cant remember what he called it. XS11 Heaven was the source, but I don't have a copy.

[jetmechmarty]

I visited Traxxion Dynamics in Woodstock, GA today. I could have saved myself a lot of headache and $$$ if I had gone there first. They know exactly what spring to put in my forks.

We decided on a .95kg/mm spring rate, because of the rake, travel, and the spindly nature (no offense meant towards your bike J ) of the forks.

They also have the same emulators as RaceTech for less money and would have done a precision job of drilling my damper rods and tuned them for me. I could have also come away with proper shocks for about the same money as Progressive.

I'm not really a fan of progressive wound springs and Dan Anderson at Traxxion explained why. I won't try to repeat it here because I can't, and I don't care to foul the explanation.

TC,

He told me it is fine to use 8 inch spacers in your forks to accommodate the Progressive springs. The spring only has to be long enough to cover the travel, or something along those lines.

From what I know now, I would just send them the forks and let them do them right. It's more economical, unless you're just going to go with Progressive suspension.

Another thing. With the emulators, fork oil viscosity is used to control the rebound. The emulator spring preload controls compression.

I thoroughly enjoyed the tour of the whole facility!

[TopCatGr58]

Well,

I decided to change the fork oil on mine since it had been since 2000 that I had done it! Remember, I've only put about 12k miles on it since the rebuild, it's not a daily rider! When I drained it, the bottom ~1/4 was rather BLACK, but then the lighter clear actual FORK OIL flowed out as well.

I tried putting the new oil( Using Dexron II/III GTX brand ATF) in thru the schraeder valve opening in the nut...removed the entire valve body, but it wouldn't flow, so I had to remove the top fork cap anyways! Found just a very small port on the inside of the cap which explained why it wouldn't flow in that way!

Pulled the 4" long spacer out( I have 4" over lengths) and then the spring just to check it. It was right at ~24.0" long, but it appeared to be a steady single rate spring even though Yamaha specified different spring rates of compression at different compression lengths??

Anyways, I decided to make a 5" long spacer to provide a little more PRELOAD tension. Also put in a bit more fluid ~250cc vs. the 210 the manual stated...partly because I have the longer tubes=more air space and easier compressible air....wanted to reduce that a bit. Was a little more "FUN" putting the caps back on, but not impossible, and didn't crossthread them!

The front feels a bit stiffer just sitting on it, and trying to push the front down in the DIVE action seemed stiffer and slower as well, not as easy to make it DIVE, but it was late, so I'll test drive it tomorrow to see how it feels. IF it feels too stiff I can always take out the longer spacer and put back the shorter ones!

I was just surprised to find the spring length at stock...especially when I've trailered Godzilla, and compress the front end when I cinch it down on the trailer, and it stays that way for sometimes 2 days straight??
T.C.