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sherpa 01-06-2006 12:13 PM

Trying to keep the 640 low fender...
 
I know I'm late to the 640 party and you "old timers" are sick and tired of hashing around the same old issues...but humor a noob will ya...:lol3

I've read all the old threads my eye's can take about the low fender issue...and several times I"ve come across mention of somebody heard of somebody else who raised the front fender 3cm or 1" or so... Here's one. I never have run across someone posting that they actually did the "low fender short lift kit mod".

I'd like to try to keep the low fender...but I need a little education about forks.

The manual of my 05 says the front forks have a travel of 10.5" or 275mm...well 275mm is actually 10 13/16"...so I'm gonna assume they are more accurate in the metric system and use the 10 13/16" measurement.

I took some measurements with the bike on the centerstand and a jack under the skidplate to get the front wheel in the air.

There is exactly 10 13/16" of stanchion tube hanging out of the upper fork tube.

There is 10 13/16" of clearance between the low fender and the bottom of the lower triple...only 10 9/16" between the fender and the black plastic brake line retainer.

I need to know what acts as the stop for fork travel. I assume there is something internally? There must be something to prevent the upper fork tube from traveling all the way down the stanchion, until the seal and retaining spring bangs into the lower axle clamp mount.

I only have 550 miles on my 640, and that has only included catching some small air over waterbars and stuff...never felt the front bottom out yet...the "dirt line" on the lower stanchion is 1 1/4" off the bottom. I have bottomed the Marzocchis on my GS out...and there is still 1 3/4" of stanchion left.

So I'm wondering if KTM's 275mm figure is a theoretical marketing figure, and the actual, useable fork travel is something less. Does anybody know how much of the stanchion tube is left as "free play" when the forks are bottomed out. I'd like to raise the low fender by that much...hopefully say 3/4"...

Anybody doing winter maintenance, with the forks out and can give me a figure?...what am I not seeing here? :ear

meat popsicle 01-06-2006 01:32 PM

Heya Sherpa,

Good thought to check clearances; I saw that the 950 folks were worried about an extra inch higher on the low guard too. Sorry if I am missing some nuance to your post; it sounds like you are hoping that there is more room to raise the stock low-boy than the published specs and your measuring afford...

KTM website lists what you have already figured out:
Suspension travel front/rear 275 / 300 mm (10.83 x 11.81")

So you are thinking you have less than a half inch of additional clearance (6/16th) - probably not enough considering the other fun? (longer crossover brake line?) I know you will have fun making the Al tabs to raise the bugger! :D

Rad 01-06-2006 01:50 PM

Quote:

Originally Posted by meat popsicle
I saw that the 950 folks were worried about an extra inch

Those limp dick 950 folks; I will forward them one of the many emails I get about add'n inches :patch

rallybug 01-06-2006 02:04 PM

Quote:

Originally Posted by Rad
Those limp dick 950 folks; I will forward them one of the many emails I get about add'n inches :patch

Because you don't need them, Rad? :evil

sherpa 01-06-2006 02:29 PM

Quote:

Originally Posted by meat popsicle
Heya Sherpa,
Sorry if I am missing some nuance to your post; it sounds like you are hoping that there is more room to raise the stock low-boy than the published specs and your measuring afford...

My measuring seems to show me that if the spec of 275 mm is accurate... parts are going to go bang when you reach full compression.

I wouldn't think they would design things to go bang...so I'm questioning the accuracy of the 275 mm specification.

If 275 mm is inaccurate, and the front forks only travel say 250 mm...then I could raise the lower fender by that 25 mm...

Does that make more sense ?

grimmboy 01-06-2006 03:02 PM

If its as softly sprung as the rest of the 640's it needs stiffer springs, once installed there would probably be no bottoming issues.

meat popsicle 01-06-2006 03:16 PM

Quote:

Originally Posted by sherpa
My measuring seems to show me that if the spec of 275 mm is accurate... parts are going to go bang when you reach full compression.

I wouldn't think they would design things to go bang...so I'm questioning the accuracy of the 275 mm specification.

If 275 mm is inaccurate, and the front forks only travel say 250 mm...then I could raise the lower fender by that 25 mm...

Does that make more sense ?

Hm... above you stated that 275mm is 10 3/16 and you measured 10 9/16 between the fender and the brake line retainer (bracket) at full extension, so you should have 6/16 of clearance with the stock setup right? Again, I am measurement challenged... I measure thrice and cut, well, usually once :D

sherpa 01-06-2006 03:59 PM

Quote:

Originally Posted by grimmboy
If its as softly sprung as the rest of the 640's it needs stiffer springs, once installed there would probably be no bottoming issues.

Yeah...I don't know how this "950 Front ended" 640 compares with the other's....seems okay to me so far, but then I'm only 180 lbs...

What year do you have grimmboy?...lets get together for a ride sometime and compare our 640's..

sherpa 01-06-2006 04:04 PM

Quote:

Originally Posted by meat popsicle
Hm... above you stated that 275mm is 10 3/16 and you measured 10 9/16 between the fender and the brake line retainer (bracket) at full extension, so you should have 6/16 of clearance with the stock setup right? Again, I am measurement challenged... I measure thrice and cut, well, usually once :D

Boy...now I know why it's referrred to as the Art of Communication...:rofl ...look again...it's 10 13/16"...not 3...:deal...which means the low fender will most definitely hit the bottom of the lower triple clamp...if there is 10 13/16" of front fork travel.

I don't think there is 10 13/16" of travel...I think the manual's 275 mm spec is incorrect...I would just like to know by how much that spec is off, so that I can know how much I can safely raise the low fender...

meat popsicle 01-06-2006 04:08 PM

Quote:

Originally Posted by sherpa
Boy...now I know why it's referrred to as the Art of Communication...:rofl ...look again...it's 10 13/16"...not 3...:deal...which means the low fender will most definitely hit the bottom of the lower triple clamp...if there is 10 13/16" of front fork travel.

I don't think there is 10 13/16" of travel...I think the manual's 275 mm spec is incorrect.

:rofl The Art of Reading actually

My bad... but I have a solution for ya. Put a bit of gum (or something very sticky yet removable) on the brake line retainer and go out for a ride (slow). When you get to the first stop sign slow until you are almost stopped and JAM on the front brake. I can bottom out my forks this way (I do it to trigger traffic lights here :bluduh).

Where's the gum? :evil :ear

sherpa 01-06-2006 04:13 PM

Quote:

Originally Posted by meat popsicle
:rofl The Art of Reading actually

My bad... but I have a solution for ya. Put a bit of gum (or something very sticky yet removable) on the brake line retainer and go out for a ride (slow). When you get to the first stop sign slow until you are almost stopped and JAM on the front brake. I can bottom out my forks this way (I do it to trigger traffic lights here :bluduh).

Where's the gum? :evil :ear

Yeah...I sorta tried that the other day...but I couldn't get them to bottom out..guess I need to try harder. The Marzocchi's come with an "O" ring on the right stanchion for tuning purposes...instead of the gum trick...I've actually used chalk on the stanchion before to get the same info.

I was hoping maybe someone had their forks off the bike and disassembled for maintenance...and could give me a conclusive measurement.

sherpa 01-06-2006 04:16 PM

Hey... does anybody have a low fender they want to donate to science...or sell real cheap .:deal




So meat popsicle...when you do your Jam on the brakes/bottom out routine...is there still a dirt line at the bottom of the stanchion?...measure it for me will ya....

meat popsicle 01-06-2006 06:33 PM

Quote:

Originally Posted by sherpa
Hey... does anybody have a low fender they want to donate to science...or sell real cheap .:deal




So meat popsicle...when you do your Jam on the brakes/bottom out routine...is there still a dirt line at the bottom of the stanchion?...measure it for me will ya....

There has to be one somewhere that someone doesn't want... probably mostly overseas (EU and down under talk about the high fender mod alot).

"dirt line"??? :poser I am going for my inagural ride this weekend (I hope) since August 5th when I was T-Boned by an old fella in a pickup. You musta missed that story.

Plus my 2003 has WP forks so they probably won't tell you what you need to know about your Marzocchis... sorry man. Somebody will show up with an 04/05 and the info eventually.

warewolf 01-17-2006 02:55 AM

Things go bang
 
Quote:

Originally Posted by sherpa
My measuring seems to show me that if the spec of 275 mm is accurate... parts are going to go bang when you reach full compression.

G'day sherpa,

There is no free-play in the fork travel/clearance. My bike in its present form can and does bottom the front guard into the triple clamps. The mudguard has some big scratches and lots of paint flaked away from hitting the bolt heads under the triple clamp.

According to my measurements, in standard trim, there is something like 18mm more travel than clearance! I've exacerbated that issue by 25mm (pulled the forks through the clamps to balance the Emig lowering links in the rear)...so there is around 40-odd mm too little clearance!! I've also backed off the compression and rebound damping (all the way) in order to get some compliance from the front end. This will also let the fork travel further through its stroke and increase the tendancy to bottom out.

Quote:

Originally Posted by sherpa
I wouldn't think they would design things to go bang...

Remember this front end setup was not designed for the 640; it was ported from the 950. When brand new, I had the guard rubbing on the tyre, possibly because the wider 2.15" rim was fitted after the guard was designed (for a 1.60" or 1.85" rim).

Quote:

Originally Posted by grimmboy
If its as softly sprung as the rest of the 640's it needs stiffer springs, once installed there would probably be no bottoming issues.

The '05 640 Adventure has stronger fork springs than previous years.

btw a simple fork travel measuring device consists of a cable tie around the stanchion (like the o-ring but you can retrofit it).

sherpa 01-17-2006 04:45 AM

Quote:

Originally Posted by warewolf
G'day sherpa,

There is no free-play in the fork travel/clearance. My bike in its present form can and does bottom the front guard into the triple clamps. The mudguard has some big scratches and lots of paint flaked away from hitting the bolt heads under the triple clamp.

According to my measurements, in standard trim, there is something like 18mm more travel than clearance! I've exacerbated that issue by 25mm (pulled the forks through the clamps to balance the Emig lowering links in the rear)...so there is around 40-odd mm too little clearance!! I've also backed off the compression and rebound damping (all the way) in order to get some compliance from the front end. This will also let the fork travel further through its stroke and increase the tendancy to bottom out.

Remember this front end setup was not designed for the 640; it was ported from the 950. When brand new, I had the guard rubbing on the tyre, possibly because the wider 2.15" rim was fitted after the guard was designed (for a 1.60" or 1.85" rim).

The '05 640 Adventure has stronger fork springs than previous years.

btw a simple fork travel measuring device consists of a cable tie around the stanchion (like the o-ring but you can retrofit it).

Thanks for the confirmation on several bits of info. warewolf...:thumb....my low guard has been rubbing the front tire too...I'll be going to the high guard soon.


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