Big Bore kit for the BMW DOHC engines

[shreddr]

Originally Posted by cageyar

Yea, well wait until shred and I use a vendor he knows that bores out the stock nickasel coating, applys a new coating and finish diamond hones it to 105 mm for the special order 105 mm Wossner pistons we commision.
Yea, that's right. Home grown big bore kit...............

quiet, thats a secret!

i hope there is enough cylinder liner left!

[Chris Canning]

Originally Posted by Sofatester

@Chris: Bernhard Baldes and Schüle did that. Don't know more, I'm sorry.
The times when I owned a R1100S are over since 2007.

And if you were looking to have an engine built,big bore/head/valves,who would you recommend in Germany,BBP/Wuedo/a.n. other

[zx9rmal]

Originally Posted by Nail24

105?? that strikes a bell, Ken. Now I remember. It's the 105 Howitzer.

Looks like the new Harley piston truing machine.

[Sofatester]

Originally Posted by Chris Canning

And if you were looking to have an engine built,big bore/head/valves,who would you recommend in Germany,BBP/Wuedo/a.n. other

My personal recommendation:

R&R, Roedermark, Germany

BMW R1200S |

The father of co-owner Timo Roesner is Kurt Roesner who has a 30-year-long reputation as a BMW Boxer tuner and who is in the team, that helped developing the woessner piston kit. The other co-owner, Torsten Rose is a brilliant master mechanic.
Maybe I'm not that "neutral", because they are friends.
But all I can say is that some of the work on my bike I didn't do by myself was done by Torsten Rose (especially programming and dyno work).

[Sofatester]

Originally Posted by shreddr

quiet, thats a secret!

i hope there is enough cylinder liner left!

There won't be a bigborekit with 105mm bore for the hc-1200 boxer motors (such as R1200GS, R1200R, R1200RT, R1200ST or R1200S). As shreddr pointed out simply because there isn't enough cylinder material left (plus some other reasons).

Despite that, a bigborekit with another diameter will see extensive testing in some street and race bikes. More info will not be available before testing phase is passed with an "OK".

Perhaps such a kit won't ever be available if tests will produce dissatisfying results.
Any kit has to have a good quality and some impact.

[pmc847]

What is the difference between the R1200 and the HP2 cylinders? Are the studs in a different place or is it just the case bores (hp2) are larger to accommodate the 105mm cylinders? If so then I would assume that the R1200 cases could be bored to accomadate the 105mm cylinders. Your thoughts.

Philip

[shreddr]

Originally Posted by Sofatester

Any kit has to have a good quality and some impact.

that is probably the biggest piece of any potential R12S kit. the 105mm upgrade will only get you 70cc's more total, so an HP2S will go to a 1250 (stock is 1170) if you couldn't go the whole 105mm on an R12S, then you might only get 40-50cc's more which may not be enough to really offset what will no doubt be an expensive kit, cylinder, pistons, rings, rods, gaskets...lots of dough for just a little go.


now what if you bored the cylinder and put a new liner in, and then took it out to a 1300!

[pmc847]

What would be cheaper, stroke to 78mm (1249cc) or 105mm big bore (1264cc)? I like both together (1351cc).

Philip

[shreddr]

a longer stroke would require a new crank and cylinder (or base spacer). now we are talking some serious wrenching!

[pmc847]

Falcon Cranks can stroke a stock crank, I believe. Would need new rods or base spacer.

Maybe BST can make a stroker carbon fiber crank

[Dr. Curve]

14 to 1 pistons are already available for drop in on the HP2 Sport units........with lighter and stronger rods that go with them. CC products. Much less money........put not as much end power.

[Bigred455]

Offset grinding the rod journals will gain stroke, you'd have to get lucky and find an off the shelf rod or custom make one to completment it though as the rod journals will now be smaller.

[Sofatester]

Originally Posted by pmc847

What is the difference between the R1200 and the HP2 cylinders? Are the studs in a different place or is it just the case bores (hp2) are larger to accommodate the 105mm cylinders? If so then I would assume that the R1200 cases could be bored to accomadate the 105mm cylinders. Your thoughts.

Philip

Both. Plus oil transportation alongside one stud. Solving that problem to achieve a bigger bore, it would be easier to built up a complete new motor.

Longer stroke thru offset grinding is no real possibility as one of the biggest issues on the R1200S motor is the deflection of the crank at higher revs. That's a general problem with each more longstroke crank, that should stay as light as possible AND as stiff as possible against deflection AND that should going smooth at low revs while producing more hp at top revs. A classic target conflict.

Best solution would be the same as done with the HBM RS54 (origin BMW boxer) Motors used in sidecar world championship back in the late 60's/early 70's by german world champions Enders/Engelhardt : A middle bearing for the crank, they also used a crank divided into two halves. Who will do the construction and production work of the new crankcase ?

"14:1 pistons" : what a laugh. (if you want top end power and a fast revving motor) You wanna make a diesel out of it ?

I'm sorry, but some of you don't seem to realize the fact that each tuning measure will lead to a "network" of alongside-problems, such as stress on the material, bigger combustion pressures and knock problems (ignition), and all the heat problems, just to mention 3 of them.

So, developing a bigborekit which has a good quality, a good price, enough impact and which is as easy to install as the standard bore woessner kit there will be a limitation, which means a bore less than 105mm.

btw: The "1150" models had only 2mm more bore than their "1100" ancestors. It was 1130 against 1085cc. Nobody said it was useless. In fact it wasn't: A lot of old R1100S were fitted with modified "1150" cylinders. The owners know why.

[EZ-RIDER]

My R1100S is Fitted with the 1150 cc Cylinders !
And I know Why

[Bigred455]

Originally Posted by Sofatester

Both. Plus oil transportation alongside one stud. Solving that problem to achieve a bigger bore, it would be easier to built up a complete new motor.

Longer stroke thru offset grinding is no real possibility as one of the biggest issues on the R1200S motor is the deflection of the crank at higher revs. That's a general problem with each more longstroke crank, that should stay as light as possible AND as stiff as possible against deflection AND that should going smooth at low revs while producing more hp at top revs. A classic target conflict.

Best solution would be the same as done with the HBM RS54 (origin BMW boxer) Motors used in sidecar world championship back in the late 60's/early 70's by german world champions Enders/Engelhardt : A middle bearing for the crank, they also used a crank divided into two halves. Who will do the construction and production work of the new crankcase ?

"14:1 pistons" : what a laugh. (if you want top end power and a fast revving motor) You wanna make a diesel out of it ?

I'm sorry, but some of you don't seem to realize the fact that each tuning measure will lead to a "network" of alongside-problems, such as stress on the material, bigger combustion pressures and knock problems (ignition), and all the heat problems, just to mention 3 of them.

So, developing a bigborekit which has a good quality, a good price, enough impact and which is as easy to install as the standard bore woessner kit there will be a limitation, which means a bore less than 105mm.

btw: The "1150" models had only 2mm more bore than their "1100" ancestors. It was 1130 against 1085cc. Nobody said it was useless. In fact it wasn't: A lot of old R1100S were fitted with modified "1150" cylinders. The owners know why.

Great post! Thanks

[shreddr]

Originally Posted by Sofatester

Both. Plus oil transportation alongside one stud. Solving that problem to achieve a bigger bore, it would be easier to built up a complete new motor.

Longer stroke thru offset grinding is no real possibility as one of the biggest issues on the R1200S motor is the deflection of the crank at higher revs. That's a general problem with each more longstroke crank, that should stay as light as possible AND as stiff as possible against deflection AND that should going smooth at low revs while producing more hp at top revs. A classic target conflict.

Best solution would be the same as done with the HBM RS54 (origin BMW boxer) Motors used in sidecar world championship back in the late 60's/early 70's by german world champions Enders/Engelhardt : A middle bearing for the crank, they also used a crank divided into two halves. Who will do the construction and production work of the new crankcase ?

"14:1 pistons" : what a laugh. (if you want top end power and a fast revving motor) You wanna make a diesel out of it ?

I'm sorry, but some of you don't seem to realize the fact that each tuning measure will lead to a "network" of alongside-problems, such as stress on the material, bigger combustion pressures and knock problems (ignition), and all the heat problems, just to mention 3 of them.

So, developing a bigborekit which has a good quality, a good price, enough impact and which is as easy to install as the standard bore woessner kit there will be a limitation, which means a bore less than 105mm.

btw: The "1150" models had only 2mm more bore than their "1100" ancestors. It was 1130 against 1085cc. Nobody said it was useless. In fact it wasn't: A lot of old R1100S were fitted with modified "1150" cylinders. The owners know why.

the voice of reason in a cacophony of speculation! thanks Lars!

[pmc847]

I love learning this stuff. Thanks Sofatester.

Philip
"It's a great bike but I can make it better, then blow it up and then make it better again".

04 R1100S BCR # 195
03 R1100S BCR #44 R.I.P. new home with 'onekiwi'
102.3 RWHP and 76.3 Torque
1150 cc cylinders
12:1 SJBMW pistons
BMW 36 mm intake valves
Ported and polished heads (just a little) by SJBMW
'07 R1200R cams
TBs bored +3 mm
RC Engineering Injectors (370 cc/min)
Throttle bodies matched to rubber mounts matched to heads
SJBMW Exhaust Accelerator Kit (modified)
Exhaust pipe welds ground down
Laser Exhaust
Laser 2 spark Chip
InDuct
SJ PowerFilter
Ohlins
Sargant Seat
Spiegler SS Brake Lines
LED tail/stop light and turn signals
Aux Fuel Tank (6.8 gallons total)

"The world is too dangerous to live in-not because of the people who do evil, but because of the people who sit and let it happen." (Albert Einstein)

[Dr. Curve]

Sofa, you are incorrect. The 14:1 pistons are performing flawlessly in the San Jose HP2 and are winning on the track as well. There have been no issues with the setup. One of the main reasons that BMW has such narrow valve angles (21 degrees or so) is to get the flattest combustion chamber area possible............because the flatter the chamber the higher the compression can be run. None of the problems you state have occurred. I remember when "long rod" theory was rejected by some of you across the pond............and now of course, it is a taken for granted as a way to improve things up top. Not only that, ceramic coating of the piston top, valve faces, and combustion chamber all can help control the "heat" you speak of.........but are not necessary to implement a higher combustion of 14:1. Crank deflection, as you call it, will be greatly eliminated when the water cooled boxer comes because the new engine will have a shorter stroke and very wide pistons, for a very over-square engine. Do not dismiss things so totally unless you know what you are talking about. I like your comments........but try not to be so overly sure of your conclusions please. 13.5 to 1 pistons are available if you don't want the 14:1 units. To each their own.

[Guest24]

Jim, I think you are missing a point. SJBMW's HP2S is seldom operated in the low end of the rev range as a street bike would be. Also, the higher compression in a "street use" would require gasoline with higher octanes than are normally available without talking an airport FBO into selling you 100LL for street use. As you well know, air cooled bikes have thin cylinder walls already to dissipate the heat generated at normal combustion levels. So, as posted earlier, new cylinders are the only remedy. Let's face it, the air cooled boxer is at the point of diminishing returns and must head for the water cooler for some relief from the heat. Then the compression can be raised with good results. Ducati and others made the move years ago and the BMW S-series is the wave of the future if you want more hp for less weight. EZ, shreddr, cageyar and others including Lars have reached the proverbial end of the line at great cost to glean the last available hp out of their bikes. This is just what I've picked of from this and other forums. I guess the last bolt-on for the hex/DOHC will be the weighty turbo-charger.

[Sofatester]

Originally Posted by Dr. Curve

Sofa, you are incorrect. The 14:1 pistons are performing flawlessly in the San Jose HP2 and are winning on the track as well. There have been no issues with the setup. One of the main reasons that BMW has such narrow valve angles (21 degrees or so) is to get the flattest combustion chamber area possible............because the flatter the chamber the higher the compression can be run. None of the problems you state have occurred. I remember when "long rod" theory was rejected by some of you across the pond............and now of course, it is a taken for granted as a way to improve things up top. Not only that, ceramic coating of the piston top, valve faces, and combustion chamber all can help control the "heat" you speak of.........but are not necessary to implement a higher combustion of 14:1. Crank deflection, as you call it, will be greatly eliminated when the water cooled boxer comes because the new engine will have a shorter stroke and very wide pistons, for a very over-square engine. Do not dismiss things so totally unless you know what you are talking about. I like your comments........but try not to be so overly sure of your conclusions please. 13.5 to 1 pistons are available if you don't want the 14:1 units. To each their own.

I wasn't talking about HP2S at all. I don't know what the other stuff is all about. There are various theories about conrod length and a simple formula "aimed over the thumb" to determine the best conrod length in combination with a given bore and given stroke. The 128.1mm conrod length of the woessner kit for the R1200S meets those requirements perfectly - better than the shorter BMW stock parts.
BMW learned and made the HP2S stock conrods as long as the ones from the woessner kit. I never stated that the conrods of the woessner kit are too long. I'm using this kit by myself.

A water cooling system of any possible kind will never eliminate the great problems that high-revving, top-powered R1200S (way over 145 hp DIN ) motors have with crank deflection. As you pointed out yourself, a reduction of crank deflection can be achieved thru a shorter stroke and/or less-weighting cranks (or different motor constructions such as with a third middle crank bearing).

But we're talking about the existing R1200S motor and not about their 2013-water-cooled successors.

I was sure that 1:14 compression ratio is not the right weapon of choice for a R1200S motor that should last and have top end power just because I know that woessner and some tuners I know tested 1:13 and 1:13.5 ratio and rejected even that.
The existing woessner kit reaches 1:12.7 which is more than that already high figure of the stock motor (1:12.5).

Using such a high compression ratio of 1:13.5 or even 1:14 in a R1200S motor might probably work when you have a lack of power or if you go for midrange boost and accept a slight loss of top end power and if you don't want to rev the motor higher than 8400/8500 rpm.
My comment was only referring to the best tuning for top rideability AND top end power.

Some customers might wish to set the focus on midrange boost. For that, a well made 1:13.5 or 1:14 kit might be useful (although I have my doubts because of the reactions of the BMS-K).
But as I said it's never the weapon of choice for a top-end tuned R1200S.

But you're certainly right: To each their own ( Jedem das Seine )

I also never thought that we do everything better on this side of the pond. In fact we produce bad ideas and bad work too, but we just don't talk about those defeats. Also I always like to see good mechanical work and I don't care whether it is made in germany, the US. , Vietnam or if it comes from Mars. It's always the idea and the quality of work that I like. In fact, I like a lot of the stuff from BMWSJ.

Discussing technics, you will always find someone with a different view and different concepts. That makes this stuff so interesting.