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BMW K-Series ‘Bell Kaff’

Posted on September 29, 2014 by Scott in Café Racer. 38 comments


Written by Ian Lee.

There are few people amongst us who haven’t looked at the European bikes of 60s & 70s and thought: “those guys really knew how to build bikes”. Italian, German or English, the motorcycles of that age have inspired many a modern day builder to create something beautiful. The bike featured here today has been influenced by all three of the above bike building greats, the Beemer created using K-series mechanicals coupled with old school aesthetics. Built by Larry Romestant of Romestant Engineering and Design, we would like to introduce you to the ‘Bell Kaff’.


Starting by stripping back the frame, Larry fitted special bracing in order to accommodate for the fact that the engine and transmission wouldn’t form a stressed part of the frame. The use of a K1200S transmission, the fitment of twin shocks on the swing arm, and the engine being bolted to the frame required the change in frame design. Lateral arms are mounted using spherical rod bearings, in order to strengthen the frame’s backbone. According to the builder: “The Kaff is very stable, and handles well, the chassis is plenty stiff, and produces a very smooth ride.”


Italian inspiration has inspired much of the look of the bike. While the bike was stripped down, the opportunity was taken to paint the frame in Imola Green. This is the same colour used on the 1974 Ducati Supersport, the famous ‘Green Frame’ model. The fuel tank is inspired by the 74 MV Agusta America, albeit with a less square profile. Following the lines of the tank, the 750 SuperSport inspired seat is finished off with an OEM 900SS tail light.


The suspension system in the machine is a work of art. The adjustable preload shock mounts are Velocette, setting the rebound rate of the late 70s BMW swingarm and differential. The rear hub is something you won’t buy off the shelf, it’s a one-off unit turned from solid 7075 billet aluminum. At the front end sits a K75S suspension setup, sporting a Tarozzi period aluminum fork brace.


Though the brakes are both drums in keeping with the period theme, the front Suzuki GT750 4LS assembly is assisted hydraulically, with the a Patent-Pending under-tank brake mech, that converts cable energy to hydraulic and back to cable. The brake lever mechanical effort is greatly reduced, allowing single-finger lever pulls. The brake itself is modified, with competition level linings, increased cooling and beefed up link arm assemblies for reduced flex and significantly better stopping power than what was available back in the day. The bike weighs in at 529lbs dry, nearly 100lbs heavier than the bike the drum was designed for, so the brake is less than ideal, though manageable and is augmented with judicial use of engine braking, which fortunately, is massive. Future builds will sport 250 and 300mm 4LS drums of my own design, as well as Grimeca and Fontana replica 4LS units, and of course single and dual disc brakes as required.


Performance has been upgraded on the build as well, to give the angular powerplant a little more poke. The motor breathes in through K1200 FI throttle bodies, onto oversized intake runners packing 230cc injectors. Fuel management is Bosch 2.2 Motronic controlled and the exhaust system is handmade using Magni styling for inspiration.


To give the bike the look of 70s period styling, both front and rear brakes are drum units. The front end is a Suzuki GT750 four leading shoe setup, assisted through a system which converts cable energy to hydraulic then back to hydraulic, which according to the builder allows for “single-finger lever pulls”. The front brake unit itself has been upgraded using competition grade linings, ‘beefed up’ link arms assemblies, and higher cooling ability.


By raiding the BMW parts bin and putting his own touches on the build, Larry Romestant has produced a mucho modified motorcycle which is a fitting tribute to a golden age of motorcycling. As Larry puts it: “My goal was to build a bike with all the elements without looking cobbled together, rather appearing as a bike that could have been produced by BMW and would have been found on the dealer’s showroom floor, even with the 1200cc Flying Brick motor that would not be available for another decade.” We think he has certainly achieved his goal.

If you want see and hear this beautiful ‘flying brick’ cafe racer in action, hit this link.



[Hat tip to BMW Cafe Racers ]

  • TJ Martin

    Now that .. is a custom worthy of the word ‘ custom ‘ Not a favorite mind you … not even a favorite amongst the recent wave of ‘ K ‘ customs [ especially after seeing that brutal art deco locomotive ‘ K ‘ bike built by Krugger seen elsewhere ]

    But a mighty fine custom indeed !

  • Thermostat9

    It’s not an ‘airhead powerplant’. :-/

    • TJ Martin

      …. and your point is ?

      • Thermostat9

        Do you bother to read the text or do you just look at the pretty pictures? The article says “Performance has been upgraded on the build as well, to give the airhead powerplant a little more poke.” It’s not an airhead powerplant.

        • TJ Martin

          …. and again … your point being ? What .. you’ve never let loose with a typo ? Give it a rest ! Go down a little further in the text you’re claiming I didn’t read and you’ll notice Scott correctly called it a ‘ brick ‘ ( twice ) which is the nickname given to BMW’s K Series motors in case that little fact has eluded you .

          Sheesh ! Just gotta love a pedant ! Or not ! I’ll go with … not !

        • TJ Martin

          … but err … if you must … be a bit pedantic that is . At least have the online courtesy to both us as well as the author of the error to point out the mistake plainly and directly to the person involved . e.g.

          ” Scott . You incorrectly called the motor an ‘ Airhead ‘ once in the text ”

          Manners and decorum . Even online .. they do matter 😉

          • TJ Martin

            … add in proper context to the list of things that do matter

          • John Keegan

            All this call for decorum and manners from the guy that stepped way over the line in commenting on the ’12 Scrambler previously featured? Scoff.

          • Dacron Aorta

            Hey look, a patronising emoticon.

    • Yes, Ian did call it an airhead. Been fixed. cheers

  • John Keegan

    Back to the bike…nice work. Interesting frame color and choice of chrome up top. Excellent workmanship all around on the components. I gotta hand it to you for sticking with the drums front and rear after all the other fabrication aimed at upping the handling.

    • jlgace

      Were you being facetious re: the drum brakes? I can’t decide… either way it struck me as odd as well. The fascination with degrading braking performance in general in some customs leaves me confused. Now, if something came with drums that’s fine. Perhaps it’s a generational thing. I remember staring at my drums or weak single disc and wishing I had a sweet, drilled dual disc setup. Especially after a near miss.

  • MotoTrooper

    Well it’s eye catching, I’ll give it that. But the more I look at it the less I like it personally. I really like some of the builds using the K motors. They really work well in the street fighter style but in the lithe cafe style not so much. Also feel that he should’ve left the Ducati colors and put his own color scheme into play. The MV style exhausts work well on the kickstand side of the bike but can’t flow on the other. I am biased as I always liked how the stock headers snaked out and flowed into a single outlet.

    Can’t fault the effort or craftsmanship that went into it though. Must be an entertaining ride!

    • Larry Romestant

      Actually, the exhaust does flow opposite side. The mufflers have adjustable orifice restrictors and are balanced. All you have to do is strand behind her when she fires up and you will become a believer! Thanks for your comments!

      • MotoTrooper

        Sorry, should have stated, “Visually flow.” Fantastic work, just have my own opinions.

        • Larry Romestant

          Of course, and I appreciate them.

  • TwoSmoke

    Ya fuck you TJ Martin, it’s real easy to be a hypocrite when you can hide behind your keyboard and your ten dollar words. It’s people like you that ruin the enjoyment of discussion on sites like this. Get fucked you pretentious prick.

    • James duke


    • James duke

      LMAO 2 smoke 🙂 I think we would get along good brother. BJ Fartin is always rubbing folks the wrong way . He can’t help it I guess ? I’m an old phocker and rough around the edges . My 2 Bikes are good running ugly pieces of shit LMAO They leak oil and are so loud my neighbors cringe when I start em up LMAO I Love motorcycles and If I’d retire ( can’t seem to give up my work ) I’d build one of my junk sportsters into something sweet 🙂 Take care 2 smoke 🙂

  • BoxerFanatic

    I don’t usually think around the premise of backdating a more modern motorcycle to an earlier aesthetic… when the bike’s drivetrain layout is so distinct, as with a flying-brick flat-inline-3 or 4.

    But this seems to pull it off. The workmanship is amazing, and the curved black exhaust is beautifully gracious.

    It is interesting to start from a K1200S donor, that would have an aluminum spar frame to discard, rather than starting from a K100, which already has a steel tube frame, and is set up to use the engine and gearbox as a stressed member, without additional bracing.

    Also, I would think that there would be options for using a bolt-on R_GS Paralever compatible rear laced hub, rather than fabricating one… but obviously he has made this bike work, and work well, so I wouldn’t call his choices wrong ones… I would just wonder about alternative build options.

    The green frame under polished silver does strike kind of a “Paul Smart” sort of vibe.

    • John Keegan

      He did not start with a K1200S donor as is obvious by the brick motor, but utilized a K1200S tranny for the added gearing. I’d like to see the machine work for that bit of modification as it wouldn’t be a straight swap. That bit of alteration was a major need for the frame mods which started from the K100 donor platform. Given the differences at the rear of the K100 frame would make your suggestion of a R_GSswingarm setup even more problematic. And, the GS_R unit would not have the retro look of the twin shock setup he was obviously striving to achieve spoke wheels and all!

      • BoxerFanatic

        1: I should have been more precise, my mistake… the 1200 flying brick was K1200RS… the K1200S is the successor with the forward-canted transverse I4 engine. But I wasn’t the first to make that mistake.

        I was distracted by the mis-used name in the article: “The use of a K1200S transmission, the fitment of twin shocks on the swing arm, and the engine being bolted to the frame required the change in frame design.” That would be another technical error, in addition to calling a liquid cooled inline 4 as an “airhead”

        Although I thought the article mentioned that it was a 1200CC engine… but it is actually the builder the mentions it…

        “As Larry puts it: “My goal was to build a bike with all the elements without looking cobbled together, rather appearing as a bike that could have been produced by BMW and would have been found on the dealer’s showroom floor, even with the 1200cc Flying Brick motor that would not be available for another decade.””

        That suggests that it isn’t a K100 4-valve, or even a K1100 engine… it would be a K1200RS engine, if it is 1200CCs, and the K1200RS still did have the aluminum spar frame, not a tubular steel trellis/spine frame like the bikes before it… and my question still stands… why not use a K100/K1100 base, as the frame is already setup for it, without the need for external bracing?

        That, and the K1200S gearbox, and the K1200S fuel injection intake… sounds like most of the driveline parts are from the K1200, save the modified Paralever for twin shocks, and a drum brake laced rear wheel, which again, are for aesthetic, rather than purely functional reasons… and the swingarm/rear wheel mods could also have been done aft of a K1100 engine and transmission.

        Why, on a bike that is supposed to look 60’s vintage, would 6 forward gear ratios be something worth all of the frame strengthening work that is the consequence of using the K1200RS engine and transmission?

        Frankly, for a retro bike… I would have probably gone more compact, and used a K75 triple anyway, for a shorter profile. the K100, K1100, and K1200RS are LONG bikes… longer than typical 60’s iron, save maybe a classic Tonti-frame Guzzi with a long transmission behind a flying V.

        A K75-based bike wouldn’t have anywhere near the power of a K1200RS, granted, but 60’s bikes didn’t have nearly that much power, either.

        There is a LOT of seemingly extra work done here, compared to getting this look from an earlier K-bike than a K1200RS. I am just curious as to why the K1200RS was chosen as the hardware donor.

        And for all of the frame modification done, including for the dual shock perches, the odd frame angle kink under the seat pan hasn’t been remedied. Something that shows why a Tonti-framed Guzzi is a perennial classically gorgeous bike, and almost all custom K-bikes that don’t change the rear frame structure, are usually seen as slightly odd with their frame tube angles.

        As I said before, I don’t call it wrong, I just wonder about the alternative methodology to get the same aesthetic effect.

        • John Keegan

          Aha, well sorted out. It wouldn’t be the first time either a builder or blogger was imprecise in the description. However, I respectfully suggest that you are misinterpreting the quote from Larry. I don’t believe he is implying the use of the K1200, but referencing it as something, which as you note, doesn’t appear on the scene until 1997 or so. I think we’re into triple interpretations of both intent and fact as seen and written by the builder. To my eye, that’s a K100 motor with what remains of a K100 frame.

          And yes, depending on your (or my) inclinations to accomplish a more straight forward build with more common elements of design from BMW, there is a ton of extra work that doesn’t translate directly to a “better” bike. Certainly adding 100 lbs of steel isn’t the usual approach to bikes seen on these pages!

          I do, however, understand his desire to spend the enormous time and effort into the build as a) it is truly one of a kind, and b) he proved he could do it his way. Sometimes you’ve got a donor and you just start in a direction and have to finish. I just completed an oddball project of taking a ’95 Kaw VN1500 “88”, porting and grafting ’02 Meanie heads (custom oil lines and whatnot required to fabricate, not available aftermarket other fitment challenges), fueling it with a modded Ultima carb (not the first choice for a rice-o-matic Vtwin), rented time from a machine shop to grind my own cam profile, spent buccuu bucks for a set of 11:1 30 over pistons and rings, modified the trans top shaft and swapped the 4th gear set from a 97 “D” model, built a one off gas tank and fender (about 80 hours before the primer coat) and the front end of an FJR1300 with extended tubes to make it sit level. Frame mods to clear the new head configuration and re-route everything from the cooling lines to the ignition coils and wiring to matching the yoke and and stem, etc., etc.. Eighteen months later and I’m positive no-one would really appreciate the results as much as I just enjoy accomplishing something quite a few people said couldn’t be done, let alone be done in a home garage.

          And while 114 Hp and 98 Lb Ft is a far cry from the stock ’95 motor, and it does handle quite well, the results don’t equate to being ground shaking or even half smart in terms of dollars to performance.

          I just didn’t want another jap-bobber or something resembling a H-D wannabe, and it started because I inherited the donor bike unexpectedly and it was in such poor shape I couldn’t even sell it on Craigslist! So I can appreciate how this guy got to point B from wherever he started. And when I think of your comment about not usually going from newer to older, I think of the 2015 Indian Scout. Modern power plant laced into a twin shock frame and covered in sheet metal beyond my appreciation. But there it is.

          Anyway, thanks for the conversation and clarification…I even picked up tidbit of info from you!

          • BoxerFanatic

            It sounds like you have done quite a bit of work to get just what you want.

            I don’t begrudge anyone going after just exactly what they are looking for, even if it does mean a lot of custom work. It sounds like you have been going after just exactly what you want, which I think is very admirable, and commendable, especially bringing it up from a basket case.

            Mostly, my questions about the BMW above are wondering about the methodology of part A compared to alternate part B, rather than questioning the validity of the premise. He did pull off the bike in striking fashion, and the results stand on their own.

            I appreciate the discussion as well, and thank you.

          • Larry Romestant

            The engine is 2004 K1200RS, with the 6 speed gearbox. The frame is from a 97′ K1100LT. Thanks!

        • Larry Romestant

          A K75 Kaff is in development as we speak! The engine is very strong, true, but what makes the brick such a great power plant is how user-friendly and manageable it is. It can be very brutal, and at the same time very docile, while remaining smooth and extremely tractable regardless of throttle input. The K1200RS engine is the smoothest and most powerful of the 4 cylinder bricks, so it is the obvious choice for 4 cylinder models.

    • Larry Romestant

      The custom rear hub was required because the pivot span of the swing arm is too wide for a standard width hub. the spoke offset is too severe for the rim to center in the chassis in proper alignment. Even with the 9″ wide hub there is still nearly 1/4″ spoke offset, and is at the limit with keeping the spokes in the middle of the drop center. Thanks for the comments!

  • I like the German, Italian combination with a little British Velocette thrown in. I always wondered why adjustable angle shock mounts didn’t catch on. The K series motor has been a favorite of mine because it doesn’t look like a bike motor and it puts a lot of visual weight down on the pavement. Cool brakes and great metal work.

  • bjparker

    This a first class build. The green isn’t my cup of tea, but it is done exceptionally well. And the work and detail reminds you of how much goes in to a good custom.

  • Geno

    Proof read your work Ian. You’ve repeated yourself a bit buddy

  • nerg

    It’s a Brick, not a Ducati. All wrong in many ways.

    The colour and the frame are all cool (900SS style) and the engineering is magnificant.

    Stil all wrong though.

  • James duke

    This is Art, it does not have to have big performance.

  • Larry Romestant

    Please feel free to ask any questions, I will answer them as completely as possible.

    • James duke

      Well Larry I like the machine and I like good Bourbon. I’d ride it like I stole it brother LOL Great job Larry !!!!!!

  • Don Arnold

    Mis-application of heim joints on the lateral braces means they aren’t really needed. Still the coolest brick ever.

    • Larry Romestant

      Why do you say ‘mis-application of heim joints’ Don?

      • Don Arnold

        Look at the conical joints Bimota used to incorporate into removable pieces. That’s whats needed if you have real stress. Heim joints are articulated spherical joints used in control linkages or suspension pivots (in huge sizes). If you really want to use them, don’t stick them out on little cantilevered posts, get them inline, double shear. Even then the slop will allow them to move a bit while other members take the strain. Also, it seems obvious that such a long small dia member won’t do anything in compression. Also, it seem obvious that the engine is better able the keep the swingarm alignment then these things. They were always iffy on old airheads, purely cosmetic on this one. OOOOH, that’s what he was after, an historic reference!

        • Larry Romestant


          Although I appreciate your observations, I respectfully disagree with your conclusions as related specifically to my trellis frame. I more than welcome continued discussion, however not on this forum. Please PM me.