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Discussion Starter #1
I have a K7 650 and have added GIVI trunk and side cases and have the rear spring maxed out on the preload adjustment and it's not too bad with just me on it but it needs a boost. When riding 2-up it looks like the fender is about touching the tire, I weigh 230 and wife 155 and it's too much. I'll probably install Sonic springs in front this winter and change fork oil but the shock needs another spring, Race Tech has a calculator that says I need a 15.125 KG/MM spring for just me, no telling what when going 2-up. This sounds like a lot since stock is 8.2, this is nearly double that. I can't afford a shock rebuild/revalve right now but don't want to over-spring the shock and have it too bouncy with too much spring and not enough rebound. The bike only has 9000 miles so it's still like new. I would like it to be the correct ride height with no preload and allow me to crank it up when I need to. Any suggestions? What rate spring has other used? What weight fork oil and how much with new springs? Thanks.
 

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I am in just about the same boat as you, so I am hoping somebody out there has some good advice/info for you.
 

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Somebody will come on here with more knowledge, but I can tell you that most springs are progressively wound and spring rates are usually measured at one inch of compression. In other words the spring will stay at a soft rate untill compressed and then the higher rate will come in to stop the sag.
 

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I don't like progressive springs. They just add another variable into it, as the forks move and react to the oil wt., and it is a pain to deal. A proper spring is a constant and easier to play with oil etc., IMO.
 

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Spike, check in your region for suspension shops. If there is a track in the region, ask around. Klaus at EPM or Jay at Sasquatch are mail order possibilities.

Too high rate spring will give a harsh ride; think of an empty 5-ton truck.

Our stroms have a progressive action in the suspension linkage, so there is no need for a progressively wound spring.
 

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Race Tech's calculator seems really stiff to me.

My experience would indicate that you would need a spring around 10.0 or 11.0 KG/mm. I have the Sasquatch 9.6 KG/mm spring and it is just about perfect for my needs.

I have just a rear trunk and typically don't have more than 10 or 15 lbs inside. I weigh about 195 and Wifey is at about 160 (or at least I guess, LOL).

With this 9.6 spring, the sag numbers are correct with no shock preload and it is sportbike firm for me riding solo with the preload at zero turns. (= about ideal, IMO) When riding two up, I turn up the preload to about 2 or 3 rings showing, and it is acceptable. One thing which is not so good, is that I have zero unladen rear sag with the preload cranked up like this. Loaded sag (with both of us on the bike) is fine though.
The reason I mention the solo vs two-up, is that if you ride in both modes of solo or two-up, then you need to shoot for a compromise so that it doesn't turn into a bale wagon when you ride solo.

Remember that when you go to a stiffer rear spring, the rebound dampening will need to be altered to match that stiffer spring. Sasquatch can set you up with the whole modification of re-valving and a stiffer spring.

I believe some members here have gone for the stiffer spring from Sasquatch first and revalved later. Hopefully, they will comment how that worked.

Btw, If you are the math-numbers sort of guy and want to dive into it, I made a spreadsheet with some measurements to help you with sorting out the numbers.
 

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Hyperpro makes a heavy spring for the DL650. I put a DL1000 shock with a Hyperpro spring on my DL650 and it was much stiffer. Cheaper than going the shock route. Their website appears to be down. You may have to dig a bit.
 

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Get a wilbers

I had the same problem you all have.. I upgraded to a wilbers spring only on my stock rear shock and now i dont use any preload and it works great. look them up online.
 

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+1 for sasquatch. I think it's the best option for the money.
 

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Discussion Starter #11
I emailed Sasquatch and he promptly replied that he has a custom made 9.6kg spring for $145+shipping, sounds good. Are these a straight rate spring? Is the Race Tech progressive? Maybe that's why RT rate is so high.
 

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Try asking Blair at svracingparts.com if he can supply a spring at a better price. Or a regional shop will have sources. Or a regional spring maker can make one for you, perhaps at a lower cost.
 

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You want a rate between 11.2 to 11.6 kg/mm (625 to 650 lb/in) for your weight(s). You can buy a coil-over spring for around $80 to $90, but you will have to make a spacer to get enough baseline preload. I do not recommend a progressive spring. The linkage on these bikes is already very progressive, and a progressive spring amplifies the effect exponentially.
 

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My 9.6 Sasquatch spring is a straight rate spring.

If you want to save some cash and you are the type who likes to do a little homework, and you have access to a lathe, you can do this:
- Buy an Eibach spring. You can find these on Ebay etc for about $70ish. They are available in steps of 50 lbs/in, and all sorts of OD and lengths. You have to do the rate conversions to get it right. If I remember correctly, it figures out to be a 550 or 575 lb/in spring that you want.
- Buy the spring spacers from Race Tech or just make them yourself. You may need to adjust the lengths of these spacers to get the installed preload correct. Just a few mm (1/8") are enough to cause some issues.

-I would highly suspect that RT is selling Eibach springs- a) Those are Eibach part numbers on the RT site, and b) I saw some RT shock mod pictures on a ST1100 forum with an Eibach spring.
- I can measure up my old spring ID & OD to aim you in the correct direction if this is something you want to try.

All sorts of fun if you are in the mood for it. :mrgreen:

Here are the pics from the ST1100 forum.
 

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My 9.6 Sasquatch spring is a straight rate spring.

If you want to save some cash and you are the type who likes to do a little homework, and you have access to a lathe, you can do this:
- Buy an Eibach spring. You can find these on Ebay etc for about $70ish. They are available in steps of 50 lbs/in, and all sorts of OD and lengths. You have to do the rate conversions to get it right. If I remember correctly, it figures out to be a 450 or 500 lb/in spring that you want.
- Buy the spring spacers from Race Tech or just make them yourself. You may need to adjust the lengths of these spacers to get the installed preload correct. Just a few mm (1/8") are enough to cause some issues.

-I would highly suspect that RT is selling Eibach springs- a) Those are Eibach part numbers on the RT site, and b) I saw some RT shock mod pictures on a ST1100 forum with an Eibach spring.
- I can measure up my old spring ID & OD to aim you in the correct direction if this is something you want to try.

All sorts of fun if you are in the mood for it. :mrgreen:
Right on :thumbup: This is what I was referring to in my above post when I mentioned using coil-over springs. Eibach makes them and so does Hypercoil. I used a 575 lb/in Hypercoil spring on my stock shock with custom spacers. I now have a custom made long-travel shock from Cogent Dynamics with a 600 lb/in Eibach spring.

I took dozens of measurements for free sag, rider sag, and preload for both springs on my DL650. At 225 lbs in street clothes, I found the 575 lb spring to be on the light side for me. I requested the 600 lb spring on the new shock from Cogent. However, this shock provides more travel, so I'm using more sag than a stock bike would require. If I was using the stock shock, the 650 lb/in spring would be ideal for my weight (and yours).

You will need to purchase the 8" long spring (the 9" is just too long). You will need to fabricate a spacer 8-10mm wide. This way you will have ideal sag numbers when riding solo, with the hydraulic adjuster all the way out counterclockwise. When you load the bike up or ride 2-up, you will have plenty of additional preload available with the hydraulic adjuster.

You order the springs based on length (8"), rate (650 lb/in in your case), and ID (internal diameter). I believe the spring I used had an ID of 2.25 inches. I did all your homework, now put it together and let us know how it works out :mrgreen:
 

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IMO a stiffer spring is better than doing nothing, but spring rate is only one part of the equation. Putting a spring stiff enough to handle the weight you're talking about on the stock shock will result in not having enough rebound damping for that spring rate. Additionally, I really doubt that the compression damping on the stock shock will be able to deal with that much weight. You'll get your ride height correct with a stiffer spring, but I think you may cause as many problems as you fix.
 

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The stiffer spring is a great upgrade, as long as your stock shock is not too worn. I only had a 3-5k miles on my shock, and it performed very well with the heavier spring. The stock shock actually has quite a bit of damping. You can always get the stiffer spring and once your shock wears out you can send it off the Sasquatch for a rebuild. He will not charge for the stiffer spring since you will already have one.
 

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What sort of loads are you carrying? I could see this being viable option for someone riding 1-up who's weight is outside the range the stock spring can handle. OP is talking about him being 230 + his 155 lb wife + Givi trunk and side cases. That's WAY more than the stock shock is designed to deal with. I'm 170 lbs out of the shower, and with my Givi side cases on with about 20 lbs in each, it was way undersprung (preload knob maxed out) and fairly underdamped -- and it's a new shock with ~3K miles on it.
 

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What sort of loads are you carrying? I could see this being viable option for someone riding 1-up who's weight is outside the range the stock spring can handle. OP is talking about him being 230 + his 155 lb wife + Givi trunk and side cases. That's WAY more than the stock shock is designed to deal with. I'm 170 lbs out of the shower, and with my Givi side cases on with about 20 lbs in each, it was way undersprung (preload knob maxed out) and fairly underdamped -- and it's a new shock with ~3K miles on it.

Same loads as the OP mentioned, minus the side cases. The spring upgrade is a huge improvement, trust me.
 

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10kg spring for my 93kg (out of shower) body is a bit on the firm side for me translate to 560lb/inch on 205lb "net weight) - i use elka shock - It's probably about perfect if i ride it like a sportsbike on perfect pavement. I have to crank it right up close to the max when wife of about 120lbs and 30lbs of lugguage gets up on the back

it becomes about perfect for me when i have about 15lbs to 20lbs in the back. i ride over bad pavements around here. Think Manhattan (NY) in early spring before they have a chance to repair the road damage.
 
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