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[Killroy]

After calling Zero, and telling them what happened Nicholas the Customer Service Manager emailed me back.

I asked form some suspension specs and instructions so I could DIY.

He said go to a dealer -ha ha.

He did give me some specs on the Showa fork:

SPRING:
FREE LENGTH:  461.5 mm
OUTER DIAMETER:  36.2 mm
STOCK SPRING RATE:  7.4 N/mm

OIL:  SS No. 8
OIL LEVEL:  117 mm - Measured from outer tube end to oil surface (Condition: spring, spring joint, spring collar, seat rubber, slider, fork bolt are removed and dust seal touches axle holder)(I asked for a picture or a diagram, but sorry, none was provided)

I suspended the front end and took the top caps off the fork, but it looks like a fork spring compressor is needed, so I'm going to let Evolution Suspension in San Jose do the work and spec softer springs. 

I tried to calculate a spring rate for myself, but there are a lot of unknowns like preload, weight distribution, un-sprung weight, fork angle, ect., so I am going to let the pros do it.  They probably just guess it anyway. 

Anyone know the rough weight distribution?  I was going to put her on the scale.  I think I read that the SR is hard to wheely stock because of a lot of weight up front.   

[rayivers]

Thanks for the info, and the diagram!  Nicholas is a great guy, he's helped me out several times.

At a guess (hey, we're Zero owners, that's what we do!), I imagine the SR is close to 50F/50R, and very likely within the range of 45F/55R to 55F/45R. My 2.8 dirt bike is 44F/56R, which is no help at all.

If you contact the suspension shop armed with a few numbers and some specific suggestions, they'll probably appreciate it and possibly do a better job for you, regardless of what actually ends up going into the bike. So, for what it's worth - if this were my SR, with the sag numbers and ride quality mentioned previously in this thread, these are the fork springs I'd have made for it:

460mm long, 36.2mm O.D. dual-rate springs: slightly shorter for less preload; I wish I knew what minimum preload Showa uses
Spring travel  @ 203mm (8.0"): my OEM FX springs had @ 10.5" travel for nominal 9" fork travel
Initial rate  5.71 N/mm (32.6 lb/in): laden 'race' sag should increase from @ 33mm to @ 45mm depending on preload; static sag TBD
Final rate  7.18 N/mm (41.0 lb/in): this may still be a bit stiff, but will definitely control brake dive
Rate-transition 'knee'  65mm (2.56"): this gives @ 20mm additional upward travel at the initial rate, for more compliance & smoothness

Obviously any or all of these can be tweaked as needed. There might well be something similar available from one of the suspension places too, I don't know.

Showa SS-8 suspension fluid is pretty thick (36.47 cSt @ 40C, at the heavy end of the '10W' oils).  Showa SS-7 might work better for you (16.44 cSt).

Ray

[MrDude_1]

If you need custom springs, I recommend Factory Connection.  Using my cr500 for supermoto with my fat butt requires custom wound fork springs. They made me drop in springs for $20 more than the normal in stock. Drooped right in.
I know other places do this too, but they were fast and treated me right. I will buy from them again.

[Killroy]

I went to a local suspension shop and they said that that spring was OK, but the internal pre-load spacer was too much.

So, he cut off 25 mm off the pre-load spacer.  Now the total sag is ~40mm which is much better the original 25 mm.

One thing we notice is that fork travel is more like 152 mm (6") that the 159 mm (6.25") that is on the website.

The spring rate is probably suspect too.

[spacetiger]

To verify your spring rate, add a ziptie to the the fork tube.  Make sure it is snug so it stays in the place it was last pushed too.  Once the zip tie is on the fork tube, you push it up to rest it against the upper fork. 

Bike sag:  lift the front fork off the ground and measure the gap (ziptie to fork gap) created by the front weight of the bike.

Rider sag:  Now push ziptie back up the fork, then sit on the bike and raise your feet so all of your weight is carried through the suspension.  Then carefully dismount and put kickstand down.  Measure the gap (ziptie to fork) created by your weight.  Add this gap measurement to the bike sag measurement, this is the total sag.  This measurement should be around 25% of the working range of the front suspension.   Now that is a rule of thumb, it can be higher or lower than 25%.  It depends on what is happening when you are loading up the suspension (upper rend). 

Checking the upper end by using the zip tie.  After riding, check the location of the ziptie, the gap from the fork to the ziptie.  Lets say the measurement is 5".  Then you would know the total max travel used was 5" + bike sag measurement.  That total measurement should never equal the total suspension travel amount (6", I think based on your posting).  If it equal, then you are bottoming out.  You would need to increase the preload and see if this keeps you from bottoming out.  If you use max preload and are till bottoming out, You will need stronger springs.  If you find you are only using 75% to 80% of the max suspension travel, you can reduce the preload spacer length some or you can  live with this.  If you are only using ~50% or less of the suspension travel, your springs are probably too stiff.  You should swap springs to a lower rate spring.

Hopefully, some helpful guides.

Jerry