Why has nobody...

[Wapping]

.... At least nobody I have ever read of, slapped an HP2 Sport twin cam engine into a 1200 GS?

It produces way more power out of the box than the WC version, without the extra weight of the water jacket. It shoud go like feck, without all the fiddling about at Hilltop or wherever.

7/11 and 9/11 chops used to be popular in the sport's bike world and were quite fun. A friend used to run a bog standard 600 Hornet with a full-on 900cc FireBlade engine shoehorned into it, way before Honda brought out their watered down version.

The car world does it. A chum has just shoved an Audi TT engine into an early Mark 2 VW Golf with great results.

Too difficult? Can't be done? Too expensive?

 

[mikeyboy]

far too expensive,no,one is going to break a hp2

 

[sethmopp]

Not for that purpose anyway

 

[mark2jag]

not even crashed ones???

There must be a few crashed ones about but still with a good engine.

 

[Wapping]

I don't subscribe to the 'too expensive' theory.

'Specials' are sometimes expensive to build. That alone does not make them impossible as witnessed by the demand for one-off bikes centred on HD engines or sports bikes with all sorts of exotica grafted onto to them. Look at the work done (and money spent) on some HP 2's turning them into mega-moto's.

The base 1200 could be sourced quite cheaply. Any low level insurance write-off where the frame, electrics and wheels were otherwise sound are quite common and easy to find at a knockdown price. That would leave surplus funds to buy an engine, for sure.

Don't forget, you are not being asked to take a new WC, remove its engine and bolt in an HP 2 Sport engine. You are competing with the cost of a new WC, versus a basic 1200 frame and running gear, mated to a more powerful engine. Uprated or improved suspension is not difficult to find (nor particularly expensive) second hand. A steering damper would probably be a must, but that is not difficult or costly. Lighter wheels (to reduce unstrung weight) are readily available, though may add to the cost a bit.

 

[Wreford Miles]

There was a guy selling an engine a while back, he had the engine and para lever fir a bobber project - the engine is now sold, search BMW hp2

 

[Wapping]

So engines are available.

That's the expense and lack of availability theories hit beneath the waterline.

 

[Loiq]

some random german bloke fitted a HP2s into a HP2e, can't recall all the details but he seemed to have more than enough money to make up for the amount of sense he really needed.....

 

[mikeyboy]

So engines are available.

That's the expense and lack of availability theories hit beneath the waterline.

you have no excuses then
you pay for it and i will build it

 

[Wapping]

OK, so HP2S into an HP2E has been done. Loony perhaps but it's been achieved apparently.

That just leaves why HP2S into R1200GS hasn't materialised. You would probably lose the Sport's use of carbon fibre to reduce weight. I would struggle to see anyone having a complete sub-frame and seat fabricated from carbon fibre, though the beak, mudguard and (maybe) some of the cockpit could be for sure, straight off the aftermarket shelf. What the owner would probably be aiming for is a silhouette that looked the same, with just a much better power plant driving it along.

The idiot lights off the Sport's instruments (the bike has a simple warm-up routine to avoid stressing some of the internals too much) would be easy to replicate. The clocks are just clocks, if nobody wanted to go to the aesthetic problem of grafting the Sport's dashboard across.

The exhaust would not need to stay under the seat, as it is on the Sport. Albeit there are already under seat variants available for the 1200GS, which received a thumbs up from some quarters.

Tyres are not a problem, road and sports versions abound.

 

[oblertone]

It sounds to me ...

... as though the OP is talking himself into a project

 

[Nutty]

... as though the OP is talking himself into a project

Yep, I'm keeping my fingers crossed.

 

[Roberto]

Probably because the type of folks that undertake these projects aren't motivated to making a derivative special of the most common bike around these days.

 

[Yonkyo]

When i had my HP2S, i often thought how 'Awesome' that engine would be in my GSA at the time.

As although i found the HP2S engine, not quite powerful enough to cut it as a full-on sports bike. It would have been interesting in the GS.

 

[Ijustwanttoseethephotos]

The HP2 sport has about 128 bhp at the rear wheel, which probably explains why no-one has bothered.
If it produced 150+, it might be worth the effort.

 

[Wapping]

... as though the OP is talking himself into a project

Not me, not least as I don't want or need an R1200GS in any variant.

I was genuinely surprised it doesn't appear to have been done. Many of the posts from owners concentrate on the endless pursuit of power, upping horses, tweaking torque curves, de-catting, fitting ever more exotic exhaust cans (though that does most of often seem be dictated by noise made and outward aesthetics rather than any other quality) all of which becomes more difficult given the restraints of the engine and its electronic limiters.

Slap in a ready made (and much better) engine and everything is done in one go.

 

[Bendy toy]

The Hilltop (or others) remap is the simple solution to make the road bike what the original designers intended for it to be. A more peaky engine or cams could be fitted but that would spoil what the GS is all about. Shoehorning the Honda 900 engine into the Hornet 600 frame makes sense because the 600 has no mid range pull. Few riders actually use any of the 900's top end power. Most short shift all the time and ride on the extra engine capacity.

For a special GS, why not fit a totally different engine? Enough money to fund a sport or HP2 engine would get close to Skidoo stroker engine - mad top end AND great mid range lugging power. Who knows if the gearbox could cope.

Back to the GS design - the standard GS makes poor use of space around the back end. With the standard rear wheel there is space for a narrow muffler on either side of the wheel.

 

[Wapping]

As although i found the HP2S engine, not quite powerful enough to cut it as a full-on sports bike. It would have been interesting in the GS.
]

The HP2S was built for several reasons, none of which were to make a full-on road going sports bike to rival the other manufacturers' offerings.

1. It was built because they (BMW) could; the ultimate swan sang of the old Boxer engine if you like. Rumours abounded that Munich would produce a lesser version, with plastics and cheaper suspension, but they never did.... Because they didn't need to.

2 To prove that small cams could be put into the narrow Boxer head, something that pundits said was impossible.

3.. It was adapted to go endurance racing, doing quite well given its quick development. Albeit the endurance version raced with conventional forks.

The outright sports bike competition was provided by the multi-cylinder S1000RR, which has done OK against its peers.

 

[Nick V]

I've been reading this topic with interest.

I haven't had access to an HP2 Sport engine (the bikes themselves are hen's teeth here), but my '09 GSA DOES run an R1200S engine.
The main problem so far has been fuelling which, admittedly, I've sidelined because I'm generally too busy riding the bike to fiddle too much with it. Because it still uses GSA engine-management software, the bike runs very lean and has a few great gaping gaps in power delivery (off the line from idle is the worst). But this isn't rocket science to sort out.

It's the nicest thing to hear that 'THWAP' when revving at idle (12.5:1 compression + free-breathing exhaust with Akrapovic-pattern headers = Luvverly )

I think the biggest issue with slotting an HP2S engine into any GS / GSA manufactured after 2008 would be fine-tuning the engine management. Use an HP2 engine ECU, and I suspect the ECU and ZFE-High won't talk to each other.
Cue issues with instruments, ABS, ESA, ASC, RDC, ETC, ETC...
I'd love to see one done, though!

...If I were starting from scratch with (relatively) unlimited funds, building the ultimate machine to give MotoGP-wannabes the fright of their lives, I'd combine the following:
- A rolling chassis from a non-Adventure GS manufactured after 2008.
- Engine, gearbox, final drive, front suspension and brakes, and front/rear wheels from an HP2 Sport.
- Akrapovic single-silencer full race system.
- Power Commander.

 

[Wapping]

For a special GS, why not fit a totally different engine? Enough money to fund a sport or HP2 engine would get close to Skidoo stroker engine - mad top end AND great mid range lugging power. Who knows if the gearbox could cope.

Nope, that’s not the same at all.

Shoehorning a fundamentally different engine into the 1200GS frame does nothing more than create a Triumph, Ducatti or Aprilia clone, though several BMW owners might like that.

What we are looking at here is a different / better Boxer engine inside a traditional GS frame, preserving the all important heritage of the marque.