A 1200 1150?

[GS01]

I am in the process of uprating my 1150, for no reason other than I like fiddling with bikes and yes I know that pound per lb/ft it will be a waste of money but it is only money after all.

Any way whilst thinking about the various permutations I looked at the ghastly cruisers that BM did in the 90's - they look like something Herr Flick would have ridden on a cruise for rent boys.

However the bore and stroke of the R1200C series are: -

101mm x 73mm

The R1200GS/ST/etc... are the same bore and stroke so the long stroke crank does not stop the motor producing power. It appears that the R1200C is neutered by compression ratio and I assume valve size and throttle bodies.

So has anybody looked into fitting the long stroke crank into an 1150? I assume that the R1200c uses the same crank cases as the 1150 as it looks the same in the pictures I can find.

The long stroke crank would appear to give an extra 40cc, this with other modifications should make 1200GS like power and torque from the 1150 motor.

Any problems?

 

[Steptoe]

So has anybody looked into fitting the long stroke crank into an 1150?

yes - try a search. I seem to remember the words "Money pit" "for feck all benefit".

 

[GS01]

I tried a search before posting and I have tried searching on money pit. Unfortunately those two words are in common usage so a seach doesn't really narrow it down.

I have had a look on the online parts fiche and can only find short engines listed, clearly the part numbers are different from the R1200C and the 1150 as the crank has a longer throw.

So whilst it may be a money pit is it possible?

Why is there no worth while gain. High compression pistons (RT/RS) etc... should make the motor about the same as the R1200GS.

The only stumbling block, if the crank fits, would be piston speed if the RT/RS pistons are heavier than the more modern ones I would expect more vibraton.

I can't see it being much more expensive than what I plan to do in any case as the cranks are relatively cheap.

FYI - I am building a whole motor to put into the bike inorder that I can take out the standard one for storage until I come to sell the bike. It can then be returned to standard and I can sell the tuned motor on.

 

[motobiker]

So whilst it may be a money pit is it possible?

I think the man answered your question. YES.

BUT its a money pit for feck all benefit.


(just consider though - you could buy a 1200GS for the exact same effect)

 

[GS01]

I think the man answered your question. YES.

BUT its a money pit for feck all benefit.


(just consider though - you could buy a 1200GS for the exact same effect)

Any one can do that!

I think the idea of the UK's only 1200 1150 is a good one.

Canbus, EWS, final drive etc.... for reasons for not buying a 1200.

I can't see how there is little benefit, a crank is £100ish second hand plus new shells, plus work to put it together. To my reckoning that comes to less than many spend on auxillary lights or engine bars etc... that slow you down!

It is horses for courses.

If I was doing a cost benefit analysis from a purely practical point of view I wouldn't have a bike or bikes at all - for me (now) it is a leisure activity and not a form of transport for neccesity.

As I said I know pound per lb/ft it doesn't make sense but from a sensible point of view I would put my money in the bank.... or then again would I?

So WHY is there no gain, as Carol Shelby said there is no substitute for cubic capacity.

I found this on tinternet - but BMW changed the motor around the time they released the 1150.

So any comments on the below - its from the US.

The R1200C came up in conversation at our last club meeting. Someone

mentioned the rough idle when test riding during the recent open house

at Hebert's Cycles (Baton Rouge). Someone then said it was supposed to

be the connecting rod journals were offset on the crank and were *not*

180 degrees apart like a boxer should be. Supposedly BMW's research into

what cruiser owners liked about them kept pointing to the shake, rattle,

and roll. So BMW figured they would have to add some shake and rattle if

it were to sell enough to pay for itself. But then, my kids were at the

table with me playing dueling dinosaurs and I may have heard wrong.



What say ye, oh wise and benevolent Beemer Gurus? Could a 180 degree

crank fix this problem? Will I ever be able to buy an R1200RT that idles

and shifts smoothly?



====



During the Tucson press intro ride, I too noticed the Cruiser shook a lot

more at idle and seemed to have a lower idle speed than my RS. I later

asked Wolfgang Durheimer about this and whether the extra low idle and

accompanying shaking (caused by a lower idle speed) was intended (a la HD).

"Yes" was the answer!

 

[motobiker]

Steptoe asked this very question himself in 06.

Anyone here converted their 1150 to 1200cc with the barrels and pistons from a 1200C , or know of anyone who's tried it .

and then promptly answered his own query.

Just found out on ADV rider - the 1200 makes it's extra cc from the stroke, not bore. I was offered a wreck, so i'll give it a miss, can't be arsed changing the whole engine or crank.

there may have been further follow up posts or threads.. but I think its safe to assume that if the man himself cant be bothered to do this mod. and lets face it there aren't many on this forum with greater expertise or access to the parts required. - then its probably pointless even considering it.

as for why exactly? I'm sure someone with more knowledge than me will be pleased to tell you - at length.

 

[Tarka]

FYI - I am building a whole motor to put into the bike inorder that I can take out the standard one for storage until I come to sell the bike. It can then be returned to standard and I can sell the tuned motor on.

A mental state even more fecked up than mine was when I bought a second R1100GS in order to keep my first one nice and clean.

 

[Deleted account 111026]

I've checked the part numbers, the only immediate difference I can see is that the 1200 clutch uses 6 mounting bolts against the 1150s 5-off.
The rods, shells, camshaft drive sprocket, etc are the same.
Don't be discouraged, for road useage, extra torque is always welcome.
Perhaps Motorworks could offer a bit more information, they may even let you have a crank on a 'sale or return' basis, speak to Nord.
l

 

[GS01]

I have tried motorworks today, they don't have one and have nver broken a 1200C. BMW made 31,000 of them so there must be a crashed one somewhere.

A problem that may occur is the crank timing, as it appears to have been designed to run lumpy like an Harley.

 

[karlp]

Ok things to consider.

If you fit a long stroke crank and use stock pistons/ conrods then you MUST make sure that the piston skirt does not cause issues when at BDC.

Also I would expect that the piston pin may need to be moved as the piston will now protrude from the top of the bore when at TDC.

Therefore when fitting a longer stroke crank it is sometimes (usually more than less) necessary to replace the pistons with a custom design.

Once you have sorted that out you need to be sure that the piston crowns are not going to make contact with the valves.

Instead of using custom pistons it is also possible (if you can find the correct one ) to use shortened conrods.

karl

 

[Deleted account 111026]

There is enough metal on the pistons to re-work the crowns and re-depth the valve pockets, this is a positive as it reduces the loads on the rods, look at the Siebenrock kits for the airheads, the pistons are lighter than standard.
If you're re-working the crowns, the squish and CR can be set more accurately than production tolerances.
Did you know, for example, that BMW make two lengths of R1100 barrels?

 

[DrAlf]

GS01 - did you ever get round to making that R1200C special engine? Lots of talk on the web of the possibility but it doesn't seem like anyone has actually done it. So far

 

[Fanum]

THREAD HERE

 

[DrAlf]

THREAD HERE

That's my thread Fanum! And that was 1200 (K25) Heads on an R259 block. What I'm now thinking is R1200C (R259) block with K25 R1200S Heads.

 

[Fanum]

That's my thread Fanum!

I know....hence I didn't just post the pic, but a reference to the thread, as it seemed to fit

 

[Ant1967]

Why not just change the "chip" to a stage 8 from GSJohn not heard anything but good reports on these.

 

[ahebron]

Unfortunately it looks like the OP gave up but good on him for trying.
Without those who are prepared to push boundaries the world would be very boring.

http://www.ukgser.com/forums/showthread.php/174909-Tuned-motor/page3

Adrian

 

[DrAlf]

Why not just change the "chip" to a stage 8 from GSJohn not heard anything but good reports on these.

Because that won't make me go fast enough! Already running a hilltop map and a few engine tweaks but I'd like a bit more power without changing bikes - I love my old 1150.

Unfortunately it looks like the OP gave up but good on him for trying.
Without those who are prepared to push boundaries the world would be very boring.

http://www.ukgser.com/forums/showthread.php/174909-Tuned-motor/page3

Adrian

Well said. Shame this project didn't come to anything