F800GS - RXV Shiver'ed Fork Conversion

Yes, he was aware the springs are on the softer side. I think the valving and oil choice was to "stiffen" it up a bit from the stock RXV fork. I am not sure what brand of oil. I'll have to check.

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Interesting. I will have to find out what brand of oil he used. I thought all 10wt was standardized. Guess not.

Initial impression after riding to work and around town at lunch is that it is MUCH MUCH better than the stock cartrige. So far I noticed that it does not deflect on every man hole cover or pot holes. It rides right over them. Much smoother all around. No jolts. There is FAR less dive on braking and it tracks in the corners so much better it is incredible.

I do notice now that on braking instead of the front diving the rear seems to rise up. I felt it before with stock fork cartiges but it dove in front and rose in the rear. Now the rear feels like it needs to be adjusted. LOL knew that would be hapening. Probably play with the dampenig screw on the rear. I have it at stock settings so a click of dampening + adding a bit of preload to the rear may do it.

Alreday it is a huge improvement - the high speed dampening may be a bit stiff still as he set it up. May be the 10wt oil. I am not 100% sure on that and need to ride it a lot more before I decide if any adjustments are needed to the fork valving. Since the compression and rebound are adjustable now I can play with it in the range it has and see how it changes the ride/feel.

I expect I may bring it back for a valve or oil adjustment at some point. Currently it is a vast improvement over stock. Well worth the $375 spent so far.

ALSO - I think the use of the spring for the spacer (travel reducing spacer) is a great way to go. If he takes them apart again I will get pictures to post.

Nice to hear that you are happy with the result!

And of course it takes time (and testing) to set the rebound and compression as you prefer, but that is part of the fun and now you can actually do those things!

And what comes to front end diving / back end rising - you can't completely get rid of it because the fact is that proper street bike has half the travel of this bike and twice stiffer springs. These bikes are always compromise as their name says - dualsports. But I have still similar kind of fealings about the back end like you are having.


But damn your conversion has been dirt cheap..!:eek1 I spend over three times more all together (probably two times more if you don't count my bad luck with the first set of Shiver Factory forks)... But I quess first time is the most expensive (and I used only new parts).

Then again have to reming (like you said your self), that this is just part of the bill since now you have to update the rear shock too! And that really wasn't your plan at the begining, was it..

Plan?...

I started with a set of KYB forks from a YZ250F. Planned to do this same conversion. It would work just the same provided the top caps fit or could be machined to fit.

Then I read an article about Phil at Aftershocks and the adjustment he can do. Figured I'd try that route first to see if it worked. Got to his shop, forks in hand just to find out he moved out of TriValley Moto the night before I got there.

So... Then I see the thread on fork conversions & your effort to make the RXV Shiver'd forks work. I already knew about the AF1 Aprilia forum and went looking. Posted up that I was looking for a set of used Aprilia RXV forks. Got two replies. Started calling around & asking about revalve work & found a third set at Superplush Suspension in SF. Decided to have the work done by McCoy's Off Road Center because they are local. Superplush would have been my next choice for sure.

I'm really happy with the results. Now my forks are tunable and re-valveable if needed! For what it's worth my conversion would have been +$200 - $250 more but I worked out a trade for some of the work. Makes sense that mine would be 1/2 as much as yours if I went the used route vs your knew ones.

I sure would like to know the difference and ride both our bikes side by side. Not possible unless one of us take a round the world ride. Anyway, I can't wait to get the bike off road. It feels so much better just around town. Going to be fun in the dirt. :')

Oh, and speaking of plans, yes, I've always planned to get a hyperpro rear. Just wanted to improve the front first. The hyperpro is on the list for winter downtime project. All in due time. A set of risers are next.

Anyone want to buy my stock fork cartriges? They are for sale now in the flea market...

Still waiting on my RXVs. They should be here on Wednesday. The good part is that they are re-valved and ready to go once they show up.

I'm with -W-, my conversion has been much more expensive than yours even if I don't factor in the first pair of Shivers that won't work (easily anyway). I paid $250 for the RXV forks, $250 for SuperPlush to revalve, $180 for HyperPro springs and $105 for machining the feet. Add some money for shipping and new seals and I'm getting close $900. If everything works out well then it's all worth it, if it sucks then an off the shelf solution may have been better. We shall see!

Hey Gangplank or -W-, any luck finding a longer travel rear shock? I emailed ELKA and they said no way. HyperPro and Ohlins are options for custom travel units. Have you checked into either?

At least WP or Ohlins can be both modified to have longer travel. No broblem for professional suspension tuners. Mine is going to be modified at the same time when the shock is opened for revalving to fit to my riding style (and match the front fork).

Unfortunately I am not in a hurry with this conversion since I smashed my shoulder, collarbone, ribs and some other parts while doing some downhill racing and I won't be riding anything for a while..

After a bit more riding around town here is my updated reivew...

This mod is well worth the effort. The bike is more stable up front in the corners. Less brake dive and more smooth over all kinds of bumps.

I let out 4 more clicks of compression and now it feels just right over the bumps but had a touch more brake dive back into the system.
I am headed off road this weekend so after that I will know what I want to do.

Already it is a real great improvment!!

Does anyone have any suggestions on the SAG for dualsport bikes? 35 to 45mm on the front forks? -W- what did you end up with for rider SAG?

Looking at that list and talking to my tuner he used Maxima Racing Shock Fluid 10wt. A bit thicker than what you are using.

Thanks for the list!! My .50 springs still have a little too much harshness over square edge bumps. It is FAR better but not perfect yet. I am thinking of going to the .55 springs and Maxima Racing 7wt. Looks to be close to the Marzocchi and what you are using. I'm thinking the stiffer springs and lighter oils will both keep the nose up on braking a bit more high speed dampening plushness. $110 for the springs is not much to test it out.

35-45mm is way too little. Sag starting points should be ~30% front and rear (give or take) on most everything...+/-5% or so, depending on application, typically less in the rear. Its really all nebulous as different situations require different amounts of travel and spring preload, but 30% is probably the best place to start. You should be looking more like 60mm or so. IMHO, sag is best started pretty close front to rear, then adjust from there. You may find that you need to adjust the preload spacer and spring length to achieve the proper preload and sag--they're both very important, but they're quite coupled in adjustment. In general, more preload mimics compression damping, so that's one way to fine tune things.

FWIW, backing off on your low speed compression clickers should have the biggest effect on dive under braking and G-compression dipping into turns and such. It will have less effect on bumps, especially the bigger bumps. Don't swap your springs out because you think they're too soft under dive--size them based on the overall feel, then tune your braking dive preference with the compression and preload adjustments.

Also FWIW, 10w is FAR too much for your forks.

How much of your front travel have you used so far?

I want to re-due the forks on my F8gs. Currently I have Hyperpro 25mm lowering springs installed front and rear. I like the lower bike for my short legs. But I don't like the stock fork suspension. So hear is my concept on what I have to do. I am not a suspension guy so I woun't be doing the work. I will have a suspension guy do the tech stuff.

Get a used set of Marzocchi Shver 45mm forks.

Have the stock fork foot machined to accept the valving agustment unit from the donor forks.

Install spacer in the cartridge to lower the suspenion 1" (donor cartridge)

Buy new springs of a stiffer rate 1" shorter than the stock springs (stock F800GS springs)

Revalve and install, Oil hight done by suspension expert.

Is this close to what needs to be done to make this happen. I know it will depend on the donor forks as to how much machining will be required. I just want to be sure I have a basic understanding of the procedure.

LaPorte

Yes, sounds like you have it all there. I can recommend two places close to me here in Reno. J-B Machine for the machine work. They made a jig to do mine so yours shouild be easy. Mine cost $130. Yours might be less I bet even with shipping. J-B Machine PH: (775) 359-9856 Address: 1450 Greg Street, Sparks, NV 89431. Ask for Dale. He will know.

The other is Ed McCoy's Off Road in Mound house. He did mine and I'm really pleased with the results. I will be going back for a slightly stiffer spring and thinner oil eventually but for now I am happy as it is.

Not sure where in Nor. Cal you are but shipping would not be too much for you to get them to Reno to have the feet done or you can find someone there locally. Another place to have the revalve work done is Superplush suspension in SF. (If you need it I can pick up your forks from J-B and drop them off at McCoy's to get done and then sent back to you by Ed. Its not far and I have to go there again anyway....

Where do you get those figures? 1/3 would be 76mm. 25% would be 57. Sounds like a lot to me.

Correct. The dive is controlled by compression but if highspeed comp over square edge bumps needs to be adjusted then I need stiffer springs and lighter oil. OR are you saying go with the lighter oil and then stiffen the compression to prevent the dive? I am only 12 clicks out right now. I suppose I could try thinner oil and stiffer compression settings. hmmm...??

What are you suggesting - 7.5wt. According to the chart -W- posted my 10wt is MUCH thicker than Marzocchi stock 7wt. Maxima 7wt is abotu the same as Marzocchi (Spectro Golden)

Looks to be most of it. Not 100% sure but looks like its pretty far down there in terms of the dirt marks on the fork. I am going for my first off road ride this weekend. Will report back after.

Are you sure we're talking the same sag? I'm talking rider/race sag.

Talk to any suspension tuner, read any suspension book, google any 'setup tips' webpage, and race sag should start somewhere around 30%. Sportbikes have 100-120mm of travel and typically start tuning around 25-35mm sag. Dirtbikes have 300mm of travel and shoot for ~100mm.

Static sag is a little more nebulous (125 GP bikes, for instance, are topped out in the rear pretty significantly when unloaded), but in general you should see some amount of static sag. I just measured my 800 out of curiosity and was rather surprised to see that it was 48mm (Race sag is somewhere around 65mm, IIRC), but with progressive springs like the stock ones, static sag isn't all THAT indicative of anything. If you have straight rate springs, I'd expect your static sag to be somewhere on the order of 20-25mm when your race sag is set properly...about 1/3 of your race sag. At least analytically, that would indicate a spot on spring rate.

Well, I think you need lighter oil regardless. But if you need more control over the big bumps, you should really go to the valving. That's the whole point of you doing the swap, afterall.

Yes. There's overlap all over suspension tuning, but if you're going to do it right, adjust the things you're supposed to adjust to get the results you want to get.

Pretty much the standard response I've read and heard is that 5w is really the sweet spot if you're looking for a starting point to general purpose tuning.

If I were to suggest anything, it would be to put 5W in there...Something in the 15-20 range on PVD's chart (Maxima 5W was recommended to me). Set your preload/race sag to ~30%, and while you're there, verify your static sag is ~30% of that. Then tinker with the external adjustments to get your low speed in the ballpark. Base the compression on brake dive and g-outs and base the rebound on control over bigger hits (packing down over successive bumps or bucking you over a big bump). From there, fine tune the geometry using preload to get a good idea, then finalize with fork height...personally, I hate how the thing steers like a bus, so I have a LOT of fork above my triple.

At that point you can really figure out the true characteristics of your valving, then get to the main course and adjust accordingly...which is a whole 'nuther world of black magic that I only barely understand.

Find a suitable test road, and remember to take LOTS of notes.

bxr You have changed your Stock springs already correct? Currently my static sag is quite high at 60-70mm. My rider sag is small at around 25-35. Again, leads me to believe stiffer springs are in order.

Can someone measure the static sag on a stock F800GS bike? Just curious.

At any rate, Yes, I understand the overlap. I need to get the base spring rate/oil wt. correct at the start. With so much static SAG and the suggestion to go to lighter oil I'll need stiffer springs to hold the front up static and on braking & g-down in turns.

From there I will fine tune as needed for compression/rebound. This is part of getting the adjustable forks - It allows for tuning, but I need to be at the correct spring rate to begin with. Right now I think I'm running too soft a spring & too stiff oil.

I could try just thinner oil & crank down the compression but with so much static sag vs rider sag it seems stiffer springs are in need.

No. Mostly because I've got other things going on in my life, partially because I refuse to spend that much money on springs, let alone progressive springs. That 48mm static sag I quoted and ~65mm rider sag is with the stock springs.

Well, the bad--but good--news is that there's something amiss with your measurements. I'm not sure if you're just calling one thing the other thing or if the actual method you're using needs some revision, but both rider/race sag and static sag start their measurements at the same point: the top/beginning/start of the stroke. Some people actually call rider sag static sag, so that might be where your confusion lies.

In any case, rider/race sag is the amount of travel consumed by the rider and the bike, starting at the beginning of the stroke. its the amount the bike sags under the weight of the rider and the bike. This measurement is most important, and even if you don't have the right spring rate, it should still be somewhere in the 30% range.

Static sag is the same measurement, but without the rider. Its the amount of travel consumed solely by the weight of the bike. Its a secondary measurement to rider sag, and as noted, is typically an indicator whether or not your spring rate is correct...but other things like stiction can affect static sag, so its a bit less 'gospel' than rider sag. I'd say something loosely in the 10% range of total travel is about right.

If you just inverted the two measurements, you're actually in the ballpark already. If you're starting your rider sag from where your static sag stopped, you need to crank WAAAAY down on the preload. If that's the case, you'll definitely need a larger preload spacer. Get that close before you even bother messing with fluid and/or damping settings.

Actually, the opposite is true. You're not in the position to make this determination yet, but when you set your rider sag correctly and have very little static sag, that actually means you need to change to a heavier spring...and vice versa. Its got to do with the way the spring preloads.

I think the definitions are the problem. Race sag is static sag. Unless of course racetech is wrong.

From here: http://www.racetech.com/page.aspx?id=30&menuid=93#3
Q: What is "Race Sag" (Static Sag)?
A: Static Sag or Race Sag is the amount the bike compresses from fully extended, with the rider on board.

Here's how to measure it.
1. Extend forks completely & measure from the wiper to bottom of the triple clamp or from axle to a vertical reference point on the chassis. This is L1.
2.Take it off the stand, put the rider on in riding position. Get an assistant to balance the bike or have the rider hold onto something, compress suspension about 25 mm (1") and let it extend very slowly until it stops. Measure the distance between the wiper and the bottom of the triple clamp or the axle and the reference point on the chassis again. Do not bounce. This is L2. (If there were no friction in the seals the bike would come up a little further.)
3.Next lift up on the suspension and let it drop very slowly. Where it stops measure again. Do not bounce. This is L3. The reason L2 and L3 are different is due to stiction or drag in the seals and bushings. (If there were no friction in the seals or the linkage the bike would drop a little further.)
4.Half way between L1 and L2 is where it would come to rest with no friction so average those two measurements.
Static Sag = L1 - (L3 L2)/2
5.To adjust Static Sag make longer or shorter preload spacers or use the preload adjusters, if available.

"there are no magic Sag numbers. However here are some guidelines to use as starting points."

Bike Type - Front % - Front mm - Rear % - Rear mm - Rear Free Sag mm
Off-Road Bikes / 22-25% / 65-75mm / 30-33% / 95-100mm / 15-25mm
Street Bikes / 28-33% / 30-35mm / 28-33% / 30-35mm / 0-5mm

Looks like closer to 25% than 33% (1/3) for big dualsport bikes. 30% max. So for 230mm travel that would be 57mm of static sag remommended.

My actual race/static sag is probably an inch and half - 35mm.

Now, the other measurement that you (and I) were calling static sag(?) is actually the generic bike's weight sag. I have never seen it being used in the sites I've read. Based on what you put here though I need stiffer springs. My bike settles quite a lot under its own weight. Upwards of 60mm when I just pull it off the side stand. So I eaither need to increase the preload spacer or get a stiffer spring. Since the bike only sag (what you were calling static sag) is way more than 10% or 23mm.

headed down to my suspension guy today to discuss.

As noted some people call race sag static sag--I don't know why. For the sake of this discussion, lets stick with "Race" or "rider" sag for bike+rider, and--as RT calls it--"free" sag for bike only.

I'm an RT fan, BTW, but what you linked is about the most confusing description of how to check sag I've ever seen for a DIY. Its easier to just measure stiction on its own, IMHO.

Here's what a quick run to the googles found me as far as setting sag goes:
http://www.thumpertalk.com/forum/showthread.php?t=271134
http://www.procircuit.com/installation_instructions/Setting%20the%20Sag.pdf

So, like I said, start with ~60mm for race sag.

I think you're still a bit amiss with your measurements. If your free sag is 60mm as you note below, your race sag HAS to be more than that, unless you weigh less than 0 pounds. Remember, race sag is measured from the forks fully extended. Its the TOTAL amount of consumed suspension travel, not just the change in suspension travel/height when you sit on the bike...which is what I think you're measuring.

Its right in the link you provided as "free sag". Its in pretty much every other DIY as "static sag".

Again, you need to get your race sag dialed in properly, then you can see what your free sag is, then you can see where you are with spring rate.

I get the distinct impression your race sag is actually ~95mm. That would be okay if you had 12" of suspension travel, but its FAR too much for your 800 with stock travel. Crank down on the preload to see how much better you can make it. I suspect you'll have to put in a longer preload spacer.

ok. Seems this link has good info too....
http://www.superplushsuspension.com/a-techsag.htm

Free Sag (unladen) should be 5-10%. In this case 12-25mm
Rider Sag should be 25-33% or 58-75mm

I'll base my decisions on those numbers!

Also has this info: http://www.superplushsuspension.com/a-techsprings.htm "A common problem includes the use of too much preload to band-aid an under sprung or under damped fork. The problem that then arises is that the bike is held high up in the stroke all the time, adversely affecting weight transfer, and sometimes steering. The bike will also tend to want to quickly pop up in front when the brake is released."

Friday I stopped by and talked to my suspension guy. Soooo.... I was way off on my measurements. LOL! He took a look and everything is good wtih my current set up. Its a bit high on the SAG but within what he wants for a bike this heavy/style riding. Opps on all the confusion and discussion. This suspension adjustments stuff/dark arts & magic to me sometimes.


Anyway... so I clicked the compression back in (tighter clockwise) two clicks Friday. Felt spot-on riding around town. The front end stays up perfectly on braking, no dive. Man hole covers and pot holes are nearly unnoticeable.

I took it off road for the first real test on Saturday. A good off road ride, nothing too technical. Some easy to moderate stuff of local dirt roads, fire roads, gravel, some imbeded rocks and some whoop type ditches here and there. All I can say is the bike handled SOOOOOO MUCH better than I expected. -W- wasn't kidding. WOW!!

Front end tracked much better, rocks and roots are no issue. Way happy with how it turned out. More plush and not deflected by every small sized rock or root. Great response. At one point I was blasting down a dirt super-highway section at 70 mph. Out of no where there is a dry whoop. Maybe 2 ft deep and 4 feet accross. In and out, off the gas, touch of brakes and sure enough, CLUNK I bottom out the front. Absorbed it and caught air out the other side. The bike launched and landed with no problem. Plushness is goodness. If I had been doing 50 all would have been good.

No plans to change the springs unless I find myself bottoming out regularly. Great stuff!!

Be careful...a common problem wen starting out is to dial in too much low speed compression. I should manage the brake dive, but not eliminate it. Motorcycle forks (at leas the telescopic ones that we have) can and SHOULD compress to some degree under braking. It would be dangerous to dial out dive completely.

Ok, maybe no dive is the wrong way to say it. Less dive fir sure!!

Took the bike on a trip to panguitch UT last weekend. 1500 miles. Great ride & the forms worked great! A friend with a stock BMW F800GS ride it. He said it was amazing!! Traded bikes with a friend on a KTM 990 Adv. He agreed my F800GS is dialed in and plush. He also agreed it rides way better than his bike. Nice!! :'D

Do any of you guys know if the 800 fork caps (bottoms) are the same as the ones for the g650x series?

Anybody have custom fork bottoms made?


Cheers.



D