Yamaha forks on a BMW F650GS Dakar

[BMW Iceland]

Have any of you encounter the same problem as I am facing on my Funduro.

The travel of the YZ forks are 300mm (11.8") but the space from the top of the 19" tire to the lowest point on the Funduro fairing is 280mm (11.3") without the front fender and clamps in highest position. Is there a possibility to shorten the travel of the YZ fork by 25-40mm (1"-1 1/2") somehow??

[JDRadman]

Originally Posted by BMW Iceland

Have any of you encounter the same problem as I am facing on my Funduro.

The travel of the YZ forks are 300mm (11.8") but the space from the top of the 19" tire to the lowest point on the Funduro fairing is 280mm (11.3") without the front fender and clamps in highest position. Is there a possibility to shorten the travel of the YZ fork by 25-40mm (1"-1 1/2") somehow??

On all of the forks that we have done with Richard at the House of Horse Power, we have had them shortend by 1". I have not experienced any issues with bottoming or fender contact even with the stock fender. But to be fare, I havent done any 30 foot triples or even cased a doubble (on the GS) yet either.

That is the way to go...

Rad

[rc mad]

Rad's correct. Rich at hoh persuaded me to go an inch shorter. Perhaps i ought to email him and se if he'll send out the spacers too, or at least the dimensions of the spacers so i can get some made.

this thread has a dissasembled 2001 damper assembly, as i understand from seaching around on the web the spacer goes in the posistion as shown in the pic below.



That should stop the central rod in the picture (with the spring) from returning to its full length. Only issue is that the damper has to be dissasembled to get to that spot, Looks like some surgery is in the works

[BMW Iceland]

this way you shorten the extended length of the fork and the stroke, wich must increase the preload on the spring doesn't it? What I need in addition is to stop the stroke further an 1" to be safe, but that must increase the spring preload as well...........

I guess I'd better stop thinking of this, start abusing it to see what happens. I am hoping to be ready for my annual New years day riding

[komatias]

RC,

did you by any chance make those lifting links for the rear suspension? If you have the drawings it would save me a trip to the cold and damp garage...

Thanks in advance

[rc mad]

Originally Posted by BMW Iceland

this way you shorten the extended length of the fork and the stroke, wich must increase the preload on the spring doesn't it? What I need in addition is to stop the stroke further an 1" to be safe, but that must increase the spring preload as well...........

I guess I'd better stop thinking of this, start abusing it to see what happens. I am hoping to be ready for my annual New years day riding

Something like that i think Your right on the stroke thing tho, something to think tho i'd have thought by shortening the overall fork length by 1 inch your also reducing the travel by an inch too, and by uprating the springs to something more suited to the bikes weight any bottoming issues will be negliable at best What you are missing is that i'm getting a set of springs made that are 1 inch shorter than the stock yz forks.


Stock spring for the bike is .46 I'm getting a set of progressive springs made that are from .48 to .56 so a much higher spring rate, bottoming out should be a minor issue hopefully.

Running the stock yz setup i only ever rubbed the front mudguard once braking hard to avoid a baby bird in the road. no dmage and i missed the bird.

Komitas I did do the link drawing, just got to find it on the computer, stuff has moved since i installed windows 7 (backing up stuff) Give me an hour or so to dig it out, i need it anyway. Didn't get them made as work was unable to do them for me and i'd decided to get the spring weights sorted out first.

[rc mad]

Originally Posted by komatias

RC,

did you by any chance make those lifting links for the rear suspension? If you have the drawings it would save me a trip to the cold and damp garage...

Thanks in advance

Gah, not on this computer. They are on the works network tho, i'll grab them and upload em tomorrow evening.

[BMW Iceland]

Originally Posted by rc mad

Gah, not on this computer. They are on the works network tho, i'll grab them and upload em tomorrow evening.

How much are you shortening the links??

[rc mad]

Can't remember

here it is

Originally Posted by rc mad

Well, the standard dogbone is 85mm from hole centre to hole centre, by my measurements a 1 inch increase in rear height equates out to a dogbone with 76mm centres and a 2 inch height increase equates out to a dogbone with 69mm centres, not that great a difference between stock and a 2 inch lift, only 16mm at the dogbones. Sounds about right given the length of the swingarm. I took the measurements with the bike on it's centre stand so the rear is unloaded.

Took a measurement with the oem dog bones in place at the top rear of the swing arm, spot on 15 inches, removed the dogbones and shimmed the rear wheel till the top of the swingarm was at 14 inches then measured the distance between the dogbone mount holes, did the same for a 2 inch lift.

I think I'll try some at a 1 1/2 inch lift, gives some room for adjustment on the front fork if I'm out with the measurements. Also a 2 inch lift puts the back wheel on the deck with the dakar on it's centre stand


One thing i am going to do different is put a stainless insert in the dogbone where it mounts to the angle lever, the standard ones are starting to wear a bit on the bolt threads.


Typically the damn things are 26mm wide overall, means I can't use a piece of 1x 1 1/2 inch ally as 1" is 25.4mm tho i suppose 0.6mm isn't that big a deal between freinds.

Will not need to go that high now however as the forks will only be an inch longer than the stock forks so i'm going to try a 1 inch lift. Which means the links will need to be 76mm hole centre to hole centre. I think.

Might be different on your bike however.

[BMW Iceland]

Originally Posted by rc mad

Can't remember

here it is



Will not need to go that high now however as the forks will only be an inch longer than the stock forks so i'm going to try a 1 inch lift. Which means the links will need to be 76mm hole centre to hole centre. I think.

Might be different on your bike however.

RC
Indeed it is different on mine, the standard links are 53mm center to center, but have you concider using the 2" lowering link for a Funduro, I've got a kit in my workshop I'll mesure it tomorrow.

I will solve the hight with a Bitubo shock that is adjustable inter-axis length wise (range 10 mm), the con is I will loose the hydrolic preload adjuster

[WayneC1]

The pics for the Kayaba damper look very similar to the WP

The overall length for the WP is also adjusted with a spacer between the rebound spring and damper assembly top cap & yes it requires use of a shorter spring or removal of some preload spacers.

The stroke of the WP is adjusted by the use of either a spacer at the top of the hydraulic stop or a longer hydraulic stop. On the pic the white plastic tube appears to be the Kayaba hydraulic stop which sits at the top of the fork.

The stroke limiting spacer should be smaller in diameter than the ID of the fork spring. On the WP forks it is ID 14mm - OD 26mm

[BMW Iceland]

I am affraid my 05 forks are somewhat of a different design



I can not see any cartridge in there, errhhmm I have some digging to do

[WayneC1]

Not sure where your parts diagram came from but it does not seem to have the complete parts breakdown

I grabbed parts manuals for yz250 & yz426 from

http://www.carlsalter.com/motorcycle-manuals.asp

There is no year model info on the manuals so I assume they cover all models

The parts descriptions are not as detailed as the KTM/WP unfortunately

[BMW Iceland]

Originally Posted by BMW Iceland

RC
Indeed it is different on mine, the standard links are 53mm center to center, but have you concider using the 2" lowering link for a Funduro, I've got a kit in my workshop I'll mesure it tomorrow.

I will solve the hight with a Bitubo shock that is adjustable inter-axis length wise (range 10 mm), the con is I will loose the hydrolic preload adjuster

The 2" lowering link for Funduro is 69mm center to center, should be perfect if you are lifting the rear by 2"

Cheers

[komatias]

The 2" lowering link for Funduro is 69mm center to center, should be perfect if you are lifting the rear by 2"

Cheers

This could be a good/cheap option. The bearings and pivot bolt are the same size.