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Old 05-06-2013, 06:45 AM   #436
Gangplank OP
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I agree w/ Lukas. Stock is .45 (soft option) and .50 (stiffer option).
See here: http://www.af1racing.com/store/Scripts/prodList.asp?idCategory=180

I had the .50 in mine when i got them. when i had them revalved Ed McCoy was reluctant to go stiffer. In the end I added a few clicks of compression & rebound and I was happy. Same on my more recent F650 w/ YZ250 forks I wanted .52-.55 and Ed recommended .49

If you use the racetech calculator choose the donor bike and put in your weight + half of the difference in bike weight (only half or less of the added weight rides on the front & half on the rear) what does it recommend?




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Old 05-06-2013, 09:44 AM   #437
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Going by the rider sag numbers, I'm way high right now with the OEM springs and some additional preload over stock. I have at least 80mm of sag in the front, if not more. Hell, the bike by itself has at least 70mm without me on it.

Every suspension shop/guru I ask says 40-60mm sag with rider and gear. If I add enough preload to the rear shock to get it at 60mm sag, the bike rides nose down (meaning the front end settles too low) and brake dives like crazy. If I back the preload off, I blow through my travel super fast (this is a weak rear spring issue).

I was actually completely happy with the way the fork performed with the OEM rear shock. Now with the upgraded Elka shock I need a stiffer spring (front and rear) to meet their sag numbers which is why they think my shock is under-performing. Who knows how this will end up, but I'm going to try it their way first so if the thing has to go back to be re-valved it's not on my dime.

Again, the .8 rate was recommended by Traxxion Dynamics and he was pretty knowledgeable about the F800. He knew about the fork damper swap and sized accordingly. If it's not right and ends up way too stiff, guess who will get a phone call? Guess we'll find out in a few weeks when they get here.

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Old 05-06-2013, 09:48 AM   #438
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Quote:
Originally Posted by Gangplank View Post

If you use the racetech calculator choose the donor bike and put in your weight + half of the difference in bike weight (only half or less of the added weight rides on the front & half on the rear) what does it recommend?
No option on the racetech website for an Aprilia RXV bike. It does, however only weigh 268 lbs. Rider weight is handled differently than bike weight, so I don't know how accurate that calculation would be. I entered data for the F800 and got rates of either .75 or .95

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Old 05-06-2013, 03:04 PM   #439
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Some of the huskys use a version of the fork.


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Old 05-07-2013, 01:19 PM   #440
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Well, it's back together with great results. Before I started this, I went to a local abandoned road to get a baseline. The road is full of nasty potholes, and huge freeze heaves. The pictures don't do them justice as usual. It's about 1 mile of this shit. Some bigger and smaller, these are average.



That is 7" tall and very abrupt.



And that is 6" deep with a steep back exit. I don't know why pictures flatten things out so much.

The OEM dampers were good until about 20MPH. I stopped at 20 because the front end would jump up violently on the bump, or compression lock on the back of the pothole. This mimics the problem on any rough terrain. Crappy damping control.

With the new dampers installed, 20MPH is a breeze. 25, fine. 30? Yep. I quit at 40 cause the ass end was now jumping a bit wild off the bump.

So, it's not placebo folks. It works!

I did the valving myself with help from Ian McKill at Rider's Edge. He sells high flow compression pistons with custom shim stacks as a DIY kit that also includes revised rebound specs and setup notes. You recycle some of your old compression shims into the rebound/midvalve stack.



I didn't want to ship off my forks to a tuner for some black magic to be done. I wanted to go through the steps myself, and learned a LOT in the process.

Hey, BMW, are you reading this? Add $200 to the bikes price and put these dampers in from the beginning!
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Old 05-07-2013, 02:08 PM   #441
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HEY - check your ABS wire

Almost forgot - - go check your ABS wire @ the bottom of the left side fork guard. At the very bottom the ABS wire is supposed to tuck into a channel molded into the backside of the guard. It keeps the wire out of the way when you bottom out. Just follow the wire out from the sensor.

If you just slapped that puppy back on in a hurry you may have missed this detail.
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Old 05-07-2013, 02:47 PM   #442
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Hey, BMW, are you reading this? Add $200 to the bikes price and put these dampers in from the beginning!

They could spend $200 and charge $1000 for the upgrade. People would buy it.
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Old 05-07-2013, 04:27 PM   #443
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I would have paid it for sure. If they charged 2k more for a bike with only better suspension I would have been first in line.
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Old 05-07-2013, 08:19 PM   #444
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Quote:
Originally Posted by NCD View Post
Well, it's back together with great results. Before I started this, I went to a local abandoned road to get a baseline. The road is full of nasty potholes, and huge freeze heaves. The pictures don't do them justice as usual. It's about 1 mile of this shit. Some bigger and smaller, these are average.



That is 7" tall and very abrupt.



And that is 6" deep with a steep back exit. I don't know why pictures flatten things out so much.

The OEM dampers were good until about 20MPH. I stopped at 20 because the front end would jump up violently on the bump, or compression lock on the back of the pothole. This mimics the problem on any rough terrain. Crappy damping control.

With the new dampers installed, 20MPH is a breeze. 25, fine. 30? Yep. I quit at 40 cause the ass end was now jumping a bit wild off the bump.

So, it's not placebo folks. It works!

I did the valving myself with help from Ian McKill at Rider's Edge. He sells high flow compression pistons with custom shim stacks as a DIY kit that also includes revised rebound specs and setup notes. You recycle some of your old compression shims into the rebound/midvalve stack.



I didn't want to ship off my forks to a tuner for some black magic to be done. I wanted to go through the steps myself, and learned a LOT in the process.

Hey, BMW, are you reading this? Add $200 to the bikes price and put these dampers in from the beginning!

Couple of questions....

How much did it cost for th DIY kit?

Is it available for purchase?

How hard is the install/setup of this?
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Old 05-08-2013, 12:47 PM   #445
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The kit is 199. Its not cheap, but you are paying for the parts and the expertise that comes along with them. He was super nice to work with, and understands the goals of an adv bike. A lot of tuners know MX super well, but have a hard time grasping the concept of a 500lb bike going over all types of surfaces.

If you can handle the other aspects of this job, the shims are a piece of cake. Just remove and replace.

I went out and beat on it some more this morning. It really works well.

Re: springs. He also suggested springs in the mid 60s. But I have 12000 miles on the .55 Ohlins springs, and I think the are fine at my 230lbs with gear. I think air gap plays a big part along with preload. Ohlins air gap is 60mm in the orig BMW setup. I went with 80mm this time to split the diff between stock and Shiver.
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Old 05-08-2013, 01:04 PM   #446
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Yes. Air compresses. Fluid does not. More air more cushion, less air stiffer feel right?
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Old 05-08-2013, 03:43 PM   #447
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Yep. Stiff spring and big air gap, or softer spring and a small air gap both seem to be viable options.

The stiff spring big air gap was what the tuner did to my YZ conversion on my Dakar. It was the shit off road, but the road manners were less than stellar. I wanted to avoid that this go round.
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Old 05-08-2013, 03:49 PM   #448
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Yep. Stiff spring and big air gap, or softer spring and a small air gap both seem to be viable options.

The stiff spring big air gap was what the tuner did to my YZ conversion on my Dakar. It was the shit off road, but the road manners were less than stellar. I wanted to avoid that this go round.
Exactly... my tuner did the opposite on mine. Softer spring but used a smaller air gap to reduce the spongyness. Same guy did my F800GS Shiver conversion forks and now my YZ250F forks on my Dakar. Both times I used a .49-.50 spring and his revalve. My 800GS rode well off road and on.
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Old 05-12-2013, 03:24 PM   #449
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So I am a little confused on the springs to be used, can anyone correct or help me out if this is wrong??

The Shiver fork springs are shorter than the F800's.

It seems that the Shiver 45mm forks Use the same springs for all the bikes, at least as far as dimensions... Which is 41.2x462mm per Racetech. However, the spring rate can differ.

So, the next step is to get the correct spring to fit your bike(F800) by adjusting the weight off of the donor bike.

So Say you use the RXV550 as your "donor" bike. I am sure some have no idea what the donor bike was, as forks tend to get swapped out, moved around and can be second or third hand. But, the G450x, WR250 and RXV550 all use the 45mm forks with the same spring dimension( 41.2x462mm).

So, I am 170lbs no gear. The F800 is 410lbs Dry, and a RXV550 is 262lbs Dry.

I would subtract 262 from 410, giving me 148, then divide this by half(since only half weight is on front half of bike).. Giving me 74. Add this onto my weight, giving me a total of 244 lbs.

So the question is...... is this the weight that I need to calculate for when purchasing the correct spring for my forks???
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Old 05-12-2013, 07:28 PM   #450
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Why calculate the rate based on the donor bike, and not the BMW?
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