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Discussion Starter · #1 ·
So I’m rebuilding my forks while throwing in race tech .9kg/mm springs on my 06. The service manual states to fill to 93mm while race tech states 130. Which level should I go by?
Also, I weigh 200lbs and originally I was going to just use thicker 15w fork oil but with the springs should I go thinner?
 

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130mm from the top of the tube, springs out, forks collapsed. 15W will give you better damping control.
 

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I'm 195lbs, using the same springs (with emulators) and 15w oil, 130mm from the top. Is working good on the street (much better than stock anyway), have a track day coming up, so will see how the setup works there. Big thing I found when following RT's directions was the spring preload spacer length. I had to cut it 10mm shorter than recommended (then fine tune with the preload adjusters) to get the proper sag.
 

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I am about 200lbs and on my gen1 cafe racer am using .9 springs , 15w oil level 100mm but only because I reduced available travel 30mm. It works great but would be a bit stiffer than needed with full travel.
 

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Discussion Starter · #6 ·
I'm 195lbs, using the same springs (with emulators) and 15w oil, 130mm from the top. Is working good on the street (much better than stock anyway), have a track day coming up, so will see how the setup works there. Big thing I found when following RT's directions was the spring preload spacer length. I had to cut it 10mm shorter than recommended (then fine tune with the preload adjusters) to get the proper sag.
So I’m not the most well versed and I have no idea what an emulator does; I just figured I’d flush the oil with something thicker, replace the bushings (since I know for a fact the previous owner did zero maintenance), and upgrade the springs for something more my weight since I’ve been bottoming out like a motherfucker. I already threw a gsxr rear spring in so now I’m just beefing up the front. I imagine I keep the height at 130 even without them though? I wouldn’t even know how to properly adjust the preload so I’m probably gonna leave it at where rt advises.
 

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So I’m not the most well versed and I have no idea what an emulator does; I just figured I’d flush the oil with something thicker, replace the bushings (since I know for a fact the previous owner did zero maintenance), and upgrade the springs for something more my weight since I’ve been bottoming out like a motherfucker. I already threw a gsxr rear spring in so now I’m just beefing up the front. I imagine I keep the height at 130 even without them though? I wouldn’t even know how to properly adjust the preload so I’m probably gonna leave it at where rt advises.
Cartridge Emulators are a cheaper way of getting some actual adjustable valving in an emulsion tube fork such as the SV has (there are better ways, but it can get costly). 130mm oil height will be alright. As for the preload, I cut the preload spacers to RT's recommended length, but found that I had very little suspension sag (like 12mm instead of the needed 30-35mm). I cut another 10mm off of the preload spacers, then about 4 turns in on the preload adjusters got the sag I wanted. I put a small zip tie on one fork tube to see how much it was compressing and found it's stopping about 1/4" from bottoming. That's over bumps, hard braking, fast (not always smooth) twisties, pretty much perfect.
Start with RT's recommendations, and experiment from there.
 

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Did you measure 30-35mm sag with full kit, hands on bars and feet on pegs? not easy to do and measure on your own.
 

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Did you measure 30-35mm sag with full kit, hands on bars and feet on pegs? not easy to do and measure on your own.
Yes. Normal riding position, one hand against a porch post to steady, and had a buddy running the tape measurer.
 

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To specifically answer your question: yes, go with the RaceTech figure, and here is why. The beefier spring is, well, beefier, it takes up more volume and so it displaces more oil. If you fill up the fork the way you would with a stock spring, but put a bulkier spring in, there won't be enough air left above when the fork is compressed and it may feel too stiff. Don't forget that the air above the oil acts like a progressive spring of a sort, because during a quick compression the air won't leak out of there and will just get compressed. The smaller the volume, the higher the pressure during compression and it will act stiffer than you like.

For reference: I'm 170lb + gear, and I'm running 0.95s in my SV. I did follow RaceTech numbers and it was good, but later on I raised the oil level by 5mm to make it just a tad stiffer and I like it the way it is now.
 

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Discussion Starter · #11 ·
Cartridge Emulators are a cheaper way of getting some actual adjustable valving in an emulsion tube fork such as the SV has (there are better ways, but it can get costly). 130mm oil height will be alright. As for the preload, I cut the preload spacers to RT's recommended length, but found that I had very little suspension sag (like 12mm instead of the needed 30-35mm). I cut another 10mm off of the preload spacers, then about 4 turns in on the preload adjusters got the sag I wanted. I put a small zip tie on one fork tube to see how much it was compressing and found it's stopping about 1/4" from bottoming. That's over bumps, hard braking, fast (not always smooth) twisties, pretty much perfect.
Start with RT's recommendations, and experiment from there.
Product Azure Font Screenshot Rectangle

Am I blind or is the preload spacer length not listed? Pretty sure the "recommended preload" is for height of the adjuster rod sticking out the cap. I refuse to believe it wants a near half inch spacer...
 

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View attachment 59077
Am I blind or is the preload spacer length not listed? Pretty sure the "recommended preload" is for height of the adjuster rod sticking out the cap. I refuse to believe it wants a near half inch spacer...
The recommended preload of 15mm is the amount that the spring is compressed from it's free state when the fork caps are screwed back on.
 

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View attachment 59077
Am I blind or is the preload spacer length not listed? Pretty sure the "recommended preload" is for height of the adjuster rod sticking out the cap. I refuse to believe it wants a near half inch spacer...
The Race Tech springs are shorter than the OEM, it actually takes a spacer around (I don't remember the exact length off the top of my head) 100mm long. The springs come with a piece of aluminum tubing that has to be cut to length. The 15mm Kiwi Rider mentions is in fact the recommended preload with the caps screwed on. In my case it was too much, so I cut another 10mm off the spacer tubing and fine tuned it with the preload adjusters on the fork caps.
 

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Discussion Starter · #14 ·
The Race Tech springs are shorter than the OEM, it actually takes a spacer around (I don't remember the exact length off the top of my head) 100mm long. The springs come with a piece of aluminum tubing that has to be cut to length. The 15mm Kiwi Rider mentions is in fact the recommended preload with the caps screwed on. In my case it was too much, so I cut another 10mm off the spacer tubing and fine tuned it with the preload adjusters on the fork caps.
So go with 90mm per spacer?
 

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So go with 90mm per spacer?
You'll have to measure for your particular use. I don't remember the exact length I started with (it was, if I remember correctly, "around", but not "exactly" 100mm, and I have the added height of the Emulators thrown into the mix too), so start with whatever length it takes to get RT's recommended 15mm of compression, check your sag, and go from there.
 

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Discussion Starter · #16 ·
Finally got my fork apart now that everything's arrived. Discovered there's only a single washer inside (between the spring and spacer). Is this normal? From every vid i watched there's one on both sides of the spacer but the service manual I have only shows the one. Is the top one not needed due to the disc on the top cap?
 

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Finally got my fork apart now that everything's arrived. Discovered there's only a single washer inside (between the spring and spacer). Is this normal? From every vid i watched there's one on both sides of the spacer but the service manual I have only shows the one. Is the top one not needed due to the disc on the top cap?
Yes, one washer between spacer and spring.
 

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...an emulsion tube fork such as the SV has...
I am curious, why are you calling it an "emulsion tube"?

The only fluid inside your forks is oil. If you have any kind of emulsion inside your forks (defined as a mixture of two or more liquids that are normally immiscible) you are in big trouble as the oil in your tubes will lose its viscosity (required for proper suspension damping) and lubricant properties.

The proper name for the type of front suspension used on the SV is Damping Rod Forks or Single Stage Suspension.
 
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