R100GS alternative forks?

[Tbolt]

Any advice on changing the forks on a R100GS (without spending stupid money!).

Interested in any twin disc options.

Does the Suzuki DR650 front end fit (I know it’s a single disc)?

If so what are the problems?

Thanks
Gerry

 

[gog]

Check out the 'unholy union' thread on advrider Gerry. I won't link it here but its easy to find and a massive thread on just this topic. Think DRZ forks are a common swap.

 

[Tbolt]

Check out the 'unholy union' thread on advrider Gerry. I won't link it here but its easy to find and a massive thread on just this topic. Think DRZ forks are a common swap.

Thanks gog.

 

[DrFarkoff]

Any advice on changing the forks on a R100GS (without spending stupid money!).

Interested in any twin disc options.

Does the Suzuki DR650 front end fit (I know it’s a single disc)?

If so what are the problems?

Thanks
Gerry

Is it for braking improvement that you want to change to twin disc?

You will find a 320mm Rotor and the mount adapter a whole lot cheaper and easier to sort than to be changing a whole front end

You will likely lose the tubeless rims as most non BM options are centre laced rims

Also another option is a K1100 or early R1100 R1150 Calliper and machine 4mm off the mount and give yourself a 4 pot calliper

OR a Harrison 6 pot "Mini 6" Plug and play and VERY effective :Thumb


£300 ish depending on what you want I have one on mine and its impressive
You may well need to upgrade to progressive springs and the Millichamp Fork oil formula While you are at it

Still a lot easier than cobbling another front end on

 

[mikeyboy]

The main hurdle with a fork swap on g/s or gs airheads is the offset of the yokes,
The bm has a lot of offset(the distance from headstock to the stanchions.)
A lot of the off road bikes have prob 1/2 the offset.
Without fitting bespoke yokes,you end up with a really poor steering lock,and potentially a front end that behaves more like a shopping trolley.
The easiest fork /yoke setup to fit is a DRZ 400.
The steering stem is a bit longer so a simple spacer and the correct bearings will enable fitment,
However you’ll have buggerall lock if fitted to a PD,

 

[mikeyboy]

The adv rider thread is good reading,
One of the contributors is Baz at hyperpro in Holland IIRC.
and has developed a set of parts and can modify the DRZ fork legs to suit.
I’ve fitted numerous sets of DRZ forks to airhead bikes but due to the fact they all had bespoke fuel tanks ,steering lock although reduced was not a huge problem.
I’ve also had the misfortune to ride a bike that had ktm forks with the standard ktm yokes ,it was lethal.
Tankslaping on white lines etc.

 

[MickDB1]

I think I saw a post saying that f650 front end was a straight swap
Tarka put either a xtz or an Africa twin on one of his bikes
What yer actually after Gerry?? = like from swapping the forks?

 

[Nin]

And if you change the front suspension significantly, you’ll most likely need to change the rear to balance out.

Worth a chat with Baz at Hyperpro, I’ll pm you his number.

 

[Tbolt]

Thanks to all for the updates.

I have posted because I have been offered a complete DR650 front end (Forks, wheel and brakes).

I have seen some photo's of them fitted to the GS so I had to ask here before I made any decision.

They do look a very substantial set of forks and wondered if they are a worthwhile upgrade.

I understand fitting the Suzuki forks would stop me using the PD tank and headlamp fairing etc. but I have a spare GS tank.

Regarding brakes, Mike knows (because he built the bike) it has the 32cm large brake disc kit already and I had previously bought a Spiegler 4 pot calliper and 30cm disc from him. This remains a reserve option.

A 4 pot BMW (Brembo) calliper was tried but in use was not as effective as the original. This may be a master cylinder size issue.

I have used Billet 6 callipers on other bikes so I am fully aware of how good they are. I will ask Harrison if the brake they list for the GS works with the 32mm disc kit.

I shall enjoy following up on all the links advised.

Thanks
Gerry

 

[Beemerboff]

I was lucky I found a almost unused secondhand Ohlins for a pittance - the owner had run a blog detailing how useless it was, then found it hard to sell!
It came as it was removed from the bike, with 3 mm preload when the instructions said 18mm +- 3mm--!
HPN still had their cartridge inserts , and the springs in them were a perfect match for the stock Ohlins #80? spring.
So straight out of the box it was almost perfect, just a bit less compression and a bit more rebound was usually slightly better again, depending on what you were riding on, as Mr Millechamp also found out with stock forks.
The Ohlins magic carpet at both ends!

One of spring specialists, Hyperpro? used to list the springs for the HPN inserts , so with them and a Millechamp cocktail you might be close to the HPN / Ohlins combo.
For not a lot on cost or work.
The Ohlins instruction also said the damping adjuster only affected rebound, but it actually adjusted both compression and rebound, something most self styled experts have failed to notice.

Tried a few brake mods, back then 11 M/C's and parts were easy enough to find as Guzzi's had them as stock , and my local guy did resleeves while you waited you waited, so 11 mm resleeve was good ,quick and relativly cheap.
Main drawback will both alts is there is nothing to post pictures of when you are done, so they are never going to be very popular!
F650GS forks might fit , but why? stock they are nowhere near as good as the stock GS forks which actually work quite well, with a bit fine tuning to match the shock.
And if you can't fine tune no point in fitting parts from a bike 30 / 80 kg lighter!

 

[Tbolt]

Thanks Beemerboff

The rear suspension is a Wilburs 641 competition night line.

I am having this rebuilt to standard length (slightly short at present).

I will try the Millechamp cocktail on the forks. Progressive springs are fitted and I may look at the gold valve option.

The DR forks appear to offer some adjustment options.

 

[Nin]

I will try the Millechamp cocktail on the forks.

Made a very noticeable difference to my old bumblebee when I tried it.

Some of the cognoscenti are a bit dismissive of progressive springs - because it makes it harder to tune your damping as the spring rate changes or some such.

Btw I thought the forks on my old DR were hateful - I got the revalved and that improved them to just crap.

 

[Beemerboff]

A progressive spring only becomes progressive when some of the coils become coilbound , and as all the gaps seem to close by the same percentage very few do and there is little to no change in the spring rate.
And those coils that do become coilbound soon sag out solid, so if you have the progressive type with about 40% of the spring tightly wound you probably have a 200mm solid spacer and a 300mm very stiff spring!
Balance, front to rear is just as important as any abstract setting.
With the Ohlins/HPN combo I have around 65 mm rider sag at the front and around 10% less at the rear, but the ratio is the important thing- I like a soft set up and the Ohlins damping permits that, you may find the Wilbers damping suits something stiffer, perhaps 60/ 55.
If you can find them adjustable fork caps make the last couple of clicks of adjustment much easier, must have the OEM ones around somewhere if you need the size!
And post crossed in the post with Nins!

 

[Tbolt]

Btw I thought the forks on my old DR were hateful - I got the revalved and that improved them to just crap.

That's the sort of response I needed and will forget about fitting the DR forks.

 

[Tbolt]

A progressive spring only becomes progressive when some of the coils become coilbound , and as all the gaps seem to close by the same percentage very few do and there is little to no change in the spring rate.
And those coils that do become coilbound soon sag out solid, so if you have the progressive type with about 40% of the spring tightly wound you probably have a 200mm solid spacer and a 300mm very stiff spring!
Balance, front to rear is just as important as any abstract setting.
With the Ohlins/HPN combo I have around 65 mm rider sag at the front and around 10% less at the rear, but the ratio is the important thing- I like a soft set up and the Ohlins damping permits that, you may find the Wilbers damping suits something stiffer, perhaps 60/ 55.
If you can find them adjustable fork caps make the last couple of clicks of adjustment much easier, must have the OEM ones around somewhere if you need the size!
And post crossed in the post with Nins!

I have standard fork spring set up option so can test both.

If the adjustable fork caps are the ones fitted before 09/1990 I also have some of those.

Thanks
Gerry