$10000.00 won't even get you started at HPN. If you strip the bike down yourself and send them the frame to be modified you can make it with only a modified frame, WP front forks ready to fit standard front wheel, Rear Shock and the 100mm lengthened cardan shaft.
But to be honest if the rest of the bike is in good shape you don't need more than this.
It will be nice to add the 1043cc Mahle converted motor but you can add another $10000.00 for this if you go the full hog with dual spark heads, sport crank, rally clutch, oil cooler & thermostat, larger sump, different cam to increase torque plus the labour to put this whole lot together.
Improving the brakes and adding tougher wheels and large 43l tank and rally fairing are all nice to haves and surely will make life easier in some instances.
The question is though do you want a bike a do you want to travel.
Few of us can afford both.
TransAfrica - Route
I agree though that a GS will make the best platform to start your modifications for off road use.
If you want to get more info look at my website Welcome to GS Workshop
There is also a link to HPN's site.

How did it go ?
What did you build ?
What you are kind of referring to is the BMW ST model, but using "nippon" forks; i.e. the first versions of the /7 GS models.
Cool idea - feasable at a fair cost. HPN conversions is a whole different ball-game, and not a /5 and /6 project but a /7 development.

The simplicity of the beemer is -!
Realized that I have a bearing failiure in min 32/10 final drive today... 2h later I have my old 37/11 bolted on, adjusted and ready to go -

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Drive Safely,
Albert

Hello Dave, there is an article in issue 2 of BMW Motorcycle Magazine of a guy in Texas who has pretty much done what you intend to do using a /7 frame. Welded frame, RM forks WP shocks etc. Try BMW Motorcycle Magazine .

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rust & dust

Hi Brian,

BMW Motorcycle Owners of America published an article on that BMW-dirtbike contraption some years back. Very clever design! Not for Dave to fully use, but some of the ideas presented in the dirtbike conversion should he really nick! -
Simple, durable, service friendly - and affordable!

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Drive Safely,
Albert

Get a 21" rim laced onto the front hub, put some Metzler tyres on. It will give you a slightly chopper look but by the time you load the bike it will ok. You'll need a new front guard as well, even if you stick with a standard rim you need to increase the tyre to mudguard clearance as it will clog up with mud and bring you to a halt sooner or later.

Get a large capacity tank - 35 litres.

Have some pot racks made to carry some weight down low above each cylinder.

Maybe a bash plate for the sump.

Air cleaner is hard to relocate, the 75/5 just had holes in the metal shroud to let the air in. Maybe the R65 air cleaner can be made to fit with the intakes up above the engine, they are easy to close off as well if you have to wade the bike at sometime.

Get a Krauser pannier set and then make up a well braced carrier rack, then use a strap to go over the seat to take a bit of weight off the carrier.

DONT fart about trying to get increased ground clearance, it just wont work without almost starting again from scratch - by putting longer forks on the front you need to raise the back end. You cant raise the back end without building a new swingarm which has to be longer. You also have to tilt the engine/gearbox so that the universal at the back of the gearbox is not constantly being driven at its limit. You can only tilt the engine back by a few degrees because of the top tube - so you notch the top tube and need to brace it with additional welding. Then you need to muck around with the sump because the oil pickup will be suspect........it just goes on and on.

The standard road going BMWs used to go everywhere anyway, and it was only the introduction of the GS which saw the "must be an enduro" bike to go anywhere without bitumen that BMW have so successfully marketed.

Make it definatly a sump gard - 3mm thick al is good.

The G/S sump aids ground clearence .. you losse 2 litres of oil... and you'll need another dip stick ..

There are many /5s that have toured on many dirt roads .. all the modifications do is alow you to go faster .. fine if you are racing .. but if you are touring? .. add the sump plate .. tyres, fuel, luggage and go.

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Regards Frank Warner
motorcycles BMW R80 G/S 1981, BMW K11LT 1993, BMW K75 G/S

You might need a new pick-up for the sump.