ADVrider

Go Back   ADVrider > Bikes > GSpot > Parallel Universe
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 08-10-2010, 02:59 PM   #46
Gangplank OP
Advenchaintourer
 
Gangplank's Avatar
 
Joined: Jul 2003
Location: Las Vegas
Oddometer: 2,172
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?
__________________
Ride more, bark less

Gangplank screwed with this post 08-10-2010 at 05:37 PM
Gangplank is offline   Reply With Quote
Old 08-10-2010, 05:37 PM   #47
Gangplank OP
Advenchaintourer
 
Gangplank's Avatar
 
Joined: Jul 2003
Location: Las Vegas
Oddometer: 2,172
Quote:
Originally Posted by -W-


My tuner said that I could try a bit stiffer oils if I'll do more dirt/gravel road type of riding or prefer a bit more damping and therefore I have now 6.25wt Motorex oils in those (because I just did 9tkm long summer trip with lots of good roads also). For winter I will go 5wt or even lighter oils (=temperatures below -0c).

That 6.25wt blend of Motorex seems to have quite close same viscosity than original Marzocchi 7.5wt oil and much stiffer doesn't work that well with these forks according to him. But different brand oils have hugely different kind of viscosities and therefore some 7.5wt and some 10wt could have same viscosity in real life:

http://www.pvdwiki.com/images/a/a7/P...osity-Data.gif

Just to remind when playing with different oil viscosities and brands..
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.
__________________
Ride more, bark less
Gangplank is offline   Reply With Quote
Old 08-10-2010, 08:58 PM   #48
bxr140
Flame Bait
 
bxr140's Avatar
 
Joined: Jan 2007
Location: On high
Oddometer: 1,032
Quote:
Originally Posted by Gangplank
Does anyone have any suggestions on the SAG for dualsport bikes? 35 to 45mm on the front forks?
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?
bxr140 is offline   Reply With Quote
Old 08-11-2010, 07:44 AM   #49
LaPorte
Gnarly Adventurer
 
LaPorte's Avatar
 
Joined: Jul 2006
Location: Northern Ca.
Oddometer: 446
In Concept

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
__________________
If you don't know where your going don't lead!
LaPorte is offline   Reply With Quote
Old 08-11-2010, 12:47 PM   #50
Gangplank OP
Advenchaintourer
 
Gangplank's Avatar
 
Joined: Jul 2003
Location: Las Vegas
Oddometer: 2,172
Quote:
Originally Posted by LaPorte
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....


Quote:
Originally Posted by bxr140
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.
Where do you get those figures? 1/3 would be 76mm. 25% would be 57. Sounds like a lot to me.

Quote:
Originally Posted by bxr140
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.
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...??

Quote:
Originally Posted by bxr140
Also FWIW, 10w is FAR too much for your forks.
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)

Quote:
Originally Posted by bxr140
How much of your front travel have you used so far?
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.
__________________
Ride more, bark less
Gangplank is offline   Reply With Quote
Old 08-11-2010, 11:17 PM   #51
bxr140
Flame Bait
 
bxr140's Avatar
 
Joined: Jan 2007
Location: On high
Oddometer: 1,032
Quote:
Originally Posted by Gangplank
Where do you get those figures? 1/3 would be 76mm. 25% would be 57. Sounds like a lot to me.
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.

Quote:
Originally Posted by Gangplank
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.
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.

Quote:
Originally Posted by Gangplank
OR are you saying go with the lighter oil and then stiffen the compression to prevent the dive?
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.

Quote:
Originally Posted by Gangplank
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)
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.
bxr140 is offline   Reply With Quote
Old 08-12-2010, 06:32 AM   #52
Gangplank OP
Advenchaintourer
 
Gangplank's Avatar
 
Joined: Jul 2003
Location: Las Vegas
Oddometer: 2,172
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.
__________________
Ride more, bark less
Gangplank is offline   Reply With Quote
Old 08-12-2010, 08:27 AM   #53
bxr140
Flame Bait
 
bxr140's Avatar
 
Joined: Jan 2007
Location: On high
Oddometer: 1,032
Quote:
Originally Posted by Gangplank
bxr You have changed your Stock springs already correct?
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.

Quote:
Originally Posted by Gangplank
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.
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.

Quote:
Originally Posted by Gangplank
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.
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.
bxr140 is offline   Reply With Quote
Old 08-12-2010, 09:32 AM   #54
Gangplank OP
Advenchaintourer
 
Gangplank's Avatar
 
Joined: Jul 2003
Location: Las Vegas
Oddometer: 2,172
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.
__________________
Ride more, bark less
Gangplank is offline   Reply With Quote
Old 08-12-2010, 12:45 PM   #55
bxr140
Flame Bait
 
bxr140's Avatar
 
Joined: Jan 2007
Location: On high
Oddometer: 1,032
Quote:
Originally Posted by Gangplank
I think the definitions are the problem. Race sag is static sag. Unless of course racetech is wrong.
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/sho...d.php?t=271134
http://www.procircuit.com/installati...0the%20Sag.pdf

Quote:
Originally Posted by Gangplank
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.
So, like I said, start with ~60mm for race sag.

Quote:
Originally Posted by Gangplank
My actual race/static sag is probably an inch and half - 35mm.
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.

Quote:
Originally Posted by Gangplank
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.
Its right in the link you provided as "free sag". Its in pretty much every other DIY as "static sag".

Quote:
Originally Posted by Gangplank
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.
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.
bxr140 is offline   Reply With Quote
Old 08-12-2010, 01:02 PM   #56
Gangplank OP
Advenchaintourer
 
Gangplank's Avatar
 
Joined: Jul 2003
Location: Las Vegas
Oddometer: 2,172
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."
__________________
Ride more, bark less

Gangplank screwed with this post 08-12-2010 at 01:21 PM
Gangplank is offline   Reply With Quote
Old 08-16-2010, 02:28 PM   #57
Gangplank OP
Advenchaintourer
 
Gangplank's Avatar
 
Joined: Jul 2003
Location: Las Vegas
Oddometer: 2,172
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!!
__________________
Ride more, bark less
Gangplank is offline   Reply With Quote
Old 08-24-2010, 06:38 AM   #58
bxr140
Flame Bait
 
bxr140's Avatar
 
Joined: Jan 2007
Location: On high
Oddometer: 1,032
Quote:
Originally Posted by Gangplank
The front end stays up perfectly on braking, no dive.
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.
bxr140 is offline   Reply With Quote
Old 08-24-2010, 07:06 PM   #59
Gangplank OP
Advenchaintourer
 
Gangplank's Avatar
 
Joined: Jul 2003
Location: Las Vegas
Oddometer: 2,172
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
__________________
Ride more, bark less
Gangplank is offline   Reply With Quote
Old 09-07-2010, 01:30 AM   #60
D K
Gnarly Adventurer
 
Joined: Apr 2010
Location: SoCal
Oddometer: 465
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
__________________
"Did you see that?" "Yea I saw that. I did it" Bruce Willis
------------------------
07 950SE for sale in Holland - sold
08 950SE for sale in SoCal
09 FE570 patiently waiting..
D K is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 01:41 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014