The BMW GS boxer twin thread

[Padmei]

What have you done to your forks Eddie?

I've seen untold GS' all hard core & dirted up & don't believe for a minute they aren't dirt bikes. If you believe most of the KLR riders they'd say the KLR isn't a dirt bike - funny-cos it's got me a hell of a lot of gnarly places - albeit with many battle scars.

Apart from swapping WP forks for a lot of money there must be something good todo to them. I see there are progressive springs & cocktailing the fork oil stuff. Any intimators that people have seen?

[Woodman]

What have you done to your forks Eddie?

I've seen untold GS' all hard core & dirted up & don't believe for a minute they aren't dirt bikes. If you believe most of the KLR riders they'd say the KLR isn't a dirt bike - funny-cos it's got me a hell of a lot of gnarly places - albeit with many battle scars.

Apart from swapping WP forks for a lot of money there must be something good todo to them. I see there are progressive springs & cocktailing the fork oil stuff. Any intimators that people have seen?

Get some usd forks for Gonzo and put Gonzos forks on Schmidt. Whalla (sic)

[JATZ]

What size forks do you have Padmei ? I have a set of progressive springs here I took out of the Big, your more than welcome to try them

[Padmei]

Thanks I will measure up & see. Do the progressives make that much diff?

[Box'a'bits]

I've seen untold GS' all hard core & dirted up & don't believe for a minute they aren't dirt bikes. If you believe most of the KLR riders they'd say the KLR isn't a dirt bike - funny-cos it's got me a hell of a lot of gnarly places - albeit with many battle scars.

I see there are progressive springs & cocktailing the fork oil stuff. Any intimators that people have seen?

DON'T put progressive springs in. It makes it harder to tune the forks. Here's several links that might help, here & here . Anton Largiader has also done a fork rebuild on his website. You've also seen Infracophiles rebuild on his thread (from post 537).

Re fork swaps you are limited by the paralever travel. Any new fork would need to give about the same level of travel as stock.

The Marazochis can be tuned to be reasonably compliant. Mine felt good in gravel. I haven't yet taken it into any rough stuff.

[marks]

Mine has 30mm bar risers and the bars are almost vertical to get maximum height out of them and it's pretty good for me at 5'8. The forks really need some work to reduce dive and provide some compression damping though.

Eddie

I would be interested in your thoughts comparing the air head to the 950A

I would have thought the airhead would be a much more confidence inspiring ride for the vertically limited?

I also wondered if the airhead would be a better gravel sled with its low cg and torquey motor?

I cant really see what a 950 would offer an average rider (not hard chargers) over a well sorted/modded airhead?

thoughts?

[Padmei]

Hi guys. i've just posted this on olds cool in case anyone can help.
cheers

http://www.advrider.com/forums/showthread.php?t=621563

[Kokopelli]

Hi guys. i've just posted this on olds cool in case anyone can help.
cheers

http://www.advrider.com/forums/showthread.php?t=621563

This is the one that I have in my gearbox



There is also a black one. I didn't do the job myself, because getting to the seal involves a long lever and a lot of torque. I was told that either seal will work. There is also a small v-slot that needs to be sealed. Hope this is not too abstruse.

From Joerg's website:



http://jhau.maliwi.de/mot/gearbox.html

[Padmei]

Thanjks Koko.

p

[Eddieb]

I would be interested in your thoughts comparing the air head to the 950A

Take a 70's Cortina and compare it to a 2K Euro sports car.

I would have thought the airhead would be a much more confidence inspiring ride for the vertically limited?

The airhead carries it's weight much lower, even taking into consideration the average standard suspension it's way more confidence inspiring that the 950, which feels 'flighty' by comparison.
I have about the same amount of foot contact with the ground on both bikes but the PD is lower and a bit wider where the 950 is skinny and tall, and again the way the 2 bikes carry their weight is much different. Also when slding off one side of the seat to get more foot contact the GS you have to move far less on the GS as it's lower to start with.
An R80G/S was my first adv bike and I'd never done any off road riding before, I had done quite a few very easy gravel roads on sportsbikes but that was it, never even ridden a trail bike. That ride with you and Jim out to Sutherlands 2-3 years ago was my first proper off road ride. and I'm glad it was on an airhead.

I also wondered if the airhead would be a better gravel sled with its low cg and torquey motor?

It depends on how you like to ride, BMW = solid, planted stable and all those words, very cruisy and relaxed, 950 = ride it like you stole it to get the best from it. I would actually suggest yes, though I prefer the 800 motor over the thou pretty much everywhere except for distance open road work.

I've said it before but to me the 950 mid range feels flat compared to the airhead due to differences in tuning. The airheads have a monster mid range and the 800 will happily light up the rear wheel everywhere off the seal.

I cant really see what a 950 would offer an average rider (not hard chargers) over a well sorted/modded airhead?

Apart from buying a bike with well sorted suspension as standard vrs having to do it yourself that would be a tough argument.

[BMWST?]

What have you done to your forks Eddie?

I've seen untold GS' all hard core & dirted up & don't believe for a minute they aren't dirt bikes. If you believe most of the KLR riders they'd say the KLR isn't a dirt bike - funny-cos it's got me a hell of a lot of gnarly places - albeit with many battle scars.

Apart from swapping WP forks for a lot of money there must be something good todo to them. I see there are progressive springs & cocktailing the fork oil stuff. Any intimators that people have seen?

My forks FEEL as though they have very little damping at all.They are very compliant and on the road offer a very plush ride.However as soon as you start pushing them they feel quite harsh and not very responsive.Some guys do fit race tech emulators to them but i have never got to the bottom of it.Some peole say the forks have comp damping in one leg and rebound in the other.Some say one laeg does all the damping and the other does nothing.In theory the gspd forks should be quite good with 41 mm legs and relatively long travel.I beleive the 800s have smaller dia legs.When i go up to NP to get my shock i am gonna see what Mr Taylor says.

[Box'a'bits]

My forks FEEL as though they have very little damping at all.They are very compliant. However as soon as you start pushing them they feel quite harsh and not very responsive. Some guys do fit race tech emulators to them but i have never got to the bottom of it. Some peole say the forks have comp damping in one leg and rebound in the other. In theory the gspd forks should be quite good with 41 mm legs and relatively long travel. When i go up to NP to get my shock i am gonna see what Mr Taylor says.

I briefly discussed this with Robert in an e-mail when I ordered the new shock. He said in theory the Race Tech valve in the rebound leg should work. But it didn't sound as if he had experience with this.

I have also been told that in theory we could take the internals from another cartridge fork & fit those. But I haven't seen anyone discussing what forks these would come from (apart from the NLA HPN inserts).

On my bike, the ride is fine, but a bit wallowy when pressing on , which is more an issue with the rear shock (which is pretty shot).

Padmei, how much oil did you put in your gearbox at last change? Did you fill to quantity, or until it just started to dribble out of the fill hole when on the centrestand? Take the gearbox fill plug out while its on the stand & see if any comes out (an indication of an overfill). A little leak can go a long way. Unusual for it to come out the left side - you obviously use your side stand a lot. Is your breather clear (the bolt holding the earthstrap on & the speedo cable in the gearbox). Take it out & inspect it. If its blocked, then when the oil expands as the gearbox gets hot, it blows out the output shaft seals.

My last gearbox leak was an overfill. It didn't continue once I remedied that issue. If you attend to this & the breather, it may be fine.

[Eddieb]

What have you done to your forks Eddie?

Nothing, though for the black 800 (32mm forks) I did a lot of research on ADV and elsewhere and changed both the fluid viscosity and volume using different volumes in each leg as per the wisdom of the masses. From memory I went to 15 weight oil on one side and about 17.5 on the other.

That gave a noticable change, not WP but very worthwhile given it just took a couple of hours and a bottle of fork oil.

[NordieBoy]

I cant really see what a 950 would offer an average rider (not hard chargers) over a well sorted/modded airhead?

thoughts?

If you're going through a normal deep wheel rut, you'd want to be on the 950...

As Padmei/Schmidtty found yesterday.

[Phreaky Phil]

You can get the forks to feel better with some tuning of oil viscosities. The left leg does compression and the right rebound (unless someone has swapped the internals around) The compression side is done with a tapered damper rod that alters oil flow as the fork is compressed. Thats why it feels like it has no compression damping at the top of the stroke. An emulator cant be fitted to this fork leg. The right side does rebound which is done by a spring loaded valve. This works OK. If you fit an emulator it goes in this leg and then this fork leg does both compression and rebound.
Cartridge emulators usually come in pairs and one is fitted in each leg. Most forks do both comp and rebound and the compression holes in the bottom of the damper rods are drilled larger to disable them so the emulators do the work.
With the BMW GS you can only fit one in the rebound leg. Ive seen threads of people drilling the holes larger in the bottom of this leg thinking they are disabling the compression damping but there is none. If you disable the compression damping in the Compression fork leg then the 1 emulator in the other leg is trying to do all the work. If you leave the Comp leg alone and add an emulator in the rebound leg it will feel like you've gained more rebound in the early part of the stroke but you will get to much in the latter part and will mike the spiking affect of high speed hits worse. A lot of fiddling may get it ok.
Antons site shows the internals well. http://www.largiader.com/tech/gsforks/
No easy solution. The HPN inserts would be great but unavailable