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Ducati 851: classic racer build

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  • Ducati 851: classic racer build

    Hmmm, not quite sure how but this thing has both kept me sane and given my synapses conniptions at the same time. My therapist suggested it might be therapeutic to record the journey in some shape or form. I volunteered screaming it into a rubbish bin, but he didn't think that was funny, I told him it wasn't a joke, which only prompted a raised eyebrow and frantic scribbling in that bloody notebook. I swear the slippery fucker is worse than my missus for bringing up past conversations.....but in the end we compromised on PSB, so here we go....

    It's been a pretty ordinary last few years: too many deaths, early onset dementia slowly stealing my old man memory by memory, 2 x international relocations, a job I hate with a passion etc my shed is my version of a padded cell I am more than happy to lock myself in. Sometimes you can't help but think the whole world has gone certifiably insane, completely doolally-in-the-swede, so sneaking an hour or two in the shed is just relief personified: close the door? Check. Grab a bevvy? Check. Wack an old IOM/GP DVD/tape in the player? Check. Pretend North Korea has just blown the shit out of the rest of the fucked up world and you are the only survivor? Check.

    All of the above is aided by my (now) shed being a converted window-less ex-coolroom, with the insulation doing a great job of blocking out noise/intrusions/reality (not to mention the post-apocalyptic zombies) and giving a blessed bunker-like feel.

    But I digress. I was a late starter at this club racing malarkey, and an unkind work roster has always limited track time, so I'm never going to be racing for a championship. If speed was good looks I'm definitely no George Clooney....but I'm not Danny DeVito either, and I'm happy enough with that under the circumstances. You kinda get wrapped up in the "latest and greatest" bike thing for a while, thinking a better bike or improvements to the bike will make whole seconds worth of difference (they don't), but at some stage a light bulb flickered on and I started thinking about track time from a pure enjoyment rather than pure competition perspective.

    So how do you have the most fun? I'm almost as happy working on my bikes as I am riding them, either way you sort of "lose yourself" for a bit, so I thought it would be cool to build my own race bike. Why an 851? Partly it comes after swapping out my Superbike for a 749R which I have a love/hate relationship with (I hate to love it , and it loves to hate me), but it was also something a little different to the GSXR1100's, FZR1000's, ZXR750's that seemed to dominate the NZ club grids. The idea of a lightweight underdog that braked well and handled well nipping at the heels of the bulk hp IL4's just tickled my mechanical fancy. Another part of the lust-puzzle was driven by a vivid recollection of the first time I saw/heard an 851 Tricolore back in the day, at 20-odd, crackling along on a beat up RZ350 with a mate on his bus-like GPZ750 and what might as well have been a UFO boomed past, looking and sounding impossibly exotic in our "nowhere's-ville" town. This is at a time when a coffee "menu" only took up one line and the closest we had to Grand Designs was lessons in how to turn old tyres into "beautiful" swans. That damn thing gave me a fat a cat couldn't scratch and the memory has stayed with me.

    So, a quarter century on from that near seminal moment, the hunt began for a half decent 851 that wouldn't break our fragile piggy bank. It took a while but this is what eventually darkened my garage door 4 years ago: a nearly bog stock Strada (the base model "taxi-pack" version):

    Last edited by slowpoke; 31-07-2017, 05:33 AM.

  • #2
    Looking forward to updates as they come in. Subscribed.


    • #3
      It was at this point I realised I was in big trouble.....

      Changing the rear tyre I would have put money on the rims being cast from iron not aluminium, and look at the size of that truck battery! And what's up with the (cool) aluminium tank being heavier than the later model steel ones? How the fuck did Roche's WSB bike weigh 145kg's ? Did they fill the tyres/frame/tank with helium or summat?

      Also, my 749R has a quick angry bark thanks to lightweight internals and big exhaust, this thing just sounded half asleep, cantering lazily on even a free rev. There are some simple tricks to liberating a few pasta powered ponies though: cut the top off the airbox (the stock 'box is too small, has bad resonance and convoluted entry for the air runners entering at the rear), a lightweight flywheel would speed things up a bit, and they need a bigger exhaust. Just like early S4 (916) monsters the 40mm headers are too small, and an ST4 with the same 916 engine as an S4 makes a healthy bit more with it's 45mm headers. All the same a lowly Strada makes all of 90rwhp so I was going to have to muster ever brumby I could find.

      Likewise the Marzocchi M1R's were not inspiring confidence pushing the thing around the shed, let alone at speed.

      Hmmm, ok, so contrary to my original plan:
      1. It's heavy
      2. It's gutless
      3. It doesn't handle
      4. The brakes are good, but at this point they are pretty much redundant with the turn of speed available!

      The first expensive piece of the puzzle to fall into place was being offered a set of rare period correct as-new magnesium Marchesini's. Just what the doctor ordered, even if the bank manager was in disagreement. Turns out the seller also had a matching set of cast iron SP (SP = Sport Production - the equivalent of an R model these days) full floating front brake rotors, and Corsa sized rear rotor complete with a sexy lil' 2 piston Nissin "competition only" caliper from an '89 TZ250.

      Last edited by slowpoke; 31-07-2017, 05:35 AM.


      • #4
        Love a good rebuild story! Document everything no matter how smaller insignificant it may be to you at the time. You may need to refer back to it one day and others may benefit for it or it could jog their own memories from when they did something and can get you out of a pickle.

        I'm sure you're already on it, but, for Italian bikes you can get a lot of stuff still from
        Trying to think of a wise and sincere signature quote, but the only words that leap to mind are, "TITTY SPRINKLES"


        • #5
          Originally posted by TurboR1 View Post
          Love a good rebuild story! Document everything no matter how smaller insignificant it may be to you at the time. You may need to refer back to it one day and others may benefit for it or it could jog their own memories from when they did something and can get you out of a pickle.

          I'm sure you're already on it, but, for Italian bikes you can get a lot of stuff still from
          Thanks for the link, between this and the other Italian dunger I thought I'd exhausted Italian bike parts suppliers but that's a new one for me. I doubt my missus will be quite so excited though....

          That's also good advice regarding documenting everything, something I wish I had done more of (I'm talking to you Mr Cable Loom!). It would have made things a bit easier along the way. "Best laid plans" and all that, you never know when the gods are going to get angry and delay what you thought you'd be doing next week until a few months down the track.


          • #6
            So the bike was now a little lighter: progress! I also had the benefit of some old 916 parts on hand, and an old 916 brake master went on to replace the bulky 851 unit which has the reservoir incorporated, probably no worse functionally but it's an ugly looking thing. An old set of OEM 916 braided lines replaced the 25 year old OEM rubber lines. Unfortunately the sexy SBS ceramic backed HH pads I had stashed away from the 916 had to go back in the stash as they are too hard on the soft cast iron rotors, I'd have to source some organic pads instead. A 916 RH switchblock is also a nice lil' upgrade, not only is it slimline in comparison but incorporates a fast idle button which the 851 doesn't have and I stumbled across one I didn't know I had....amazing what you find hunting through old boxes! While I was mucking around with that a lanyard kill switch went on as cheap insurance.

            Next big ticket item was finding a Corsa (the Corsa was the Factory race bike of the time) replica "1 piece" carbon air box at a reasonable price to replace the problematic tiny OEM unit. They call it a "box" but as you can see below it's more of a shaped carbon plate. It doesn't really seal against the bottom of the tank, but does create a pressurised area. Remember this is the first mass produced fuel injected bike, ram air and pressurised airboxes were pretty "out there" thinking in what was up until then a 'carb'd world.

            What's up with the "1 piece airbox" bit? The 851 has a cross brace that almost splits the throttle bodies earlier Corsa bikes had a 3 piece carbon unit to fit around it, but apparently it's a bit messy. The later solution was to manufacture the air box as 1 piece and modify the brace instead to make it removable. So that's what I planned to do once the airbox arrived......

            This is where things start to snowball. Kinda like HRC parts the Ducati race parts usually aren't a simple bolt on prospect. No, it almost always entails buying other bits to make the first bit work or fit, and those secondary bits then need more unobtainable parts to make them requires some mental and financial gymnastics to plot the whole course of what at first glance seems like a simple mod.

            You can fit the airbox by itself, but you need to get air into it. So that means finding a set of Corsa carbon air runners.....which means the standard instrument pod doesn't you make an alloy copy of the (of course carbon) Corsa instrument pod...but then the clip-ons clash with the you need zero offset clip-ons....then you need the special mounts that bolt to the runners to support the fairing etc etc. (insert heavy sigh here). Finally all done, all mounted, but the black alloy instrument pod that although looked fine in isolation bugged me against the carbon so another reach for the pocket and a carbon replica unit replaced it.

            And you end up with something like this once you've faffed around making hombrewed versions of all the special mountings that you just can't find these days (no, not my bike, ):

            Edit: a pleasant side effect of the Corsa intake is it also fulfils the function of the heavy steel front subframe, so that's a bit more weight in the bin. Thanks go to Peter at Oro Nero for doing me a great price on a slight factory second perfect for a race application:
            Last edited by slowpoke; 01-08-2017, 11:26 PM.


            • #7
              Subbed I love the 851's the bike that made the bike that made modern ducati the 916.
              Big fan of the 750F1 too


              • #8
                Originally posted by whowalks View Post
                Subbed I love the 851's the bike that made the bike that made modern ducati the 916.
                Big fan of the 750F1 too
                there's a 750 f coming up for sale soon

                Straightline2ten your motorcycle and motor car repairer for smash repairs

                insurance or private work, plastic welding,resprays, restoration and classics

                dianella 93703770


                • #9
                  Originally posted by potato View Post
                  there's a 750 f coming up for sale soon
                  unless its $10.50 I cant afford it, the way my daughter drives LOL


                  • #10
                    So where's my bloody airbox then? It's been 2 months and no show. I spoke to the seller and he was very kind to offer a refund, so I was happy enough not to be out a few hundy but it meant more chicken scratching around the 'net trying to find another one.....

                    While that was playing out I'd also been looking at front end options as the Marzocchi RWU forks weren't inspiring confidence and were not an easy fix. It all came down to the NZ rules for the "pre-89" class, where you could only use USD forks if they were the original fitment on the bike before 31 Dec '89. There was a faint ray of expensive hope in that the Sport Production models were fitted with super-sexy (for the time) Ohlins FG9050 USD forks but they really are unicorn material, super rare to see them advertised separately and priced accordingly.

                    Then I found a lil' gem of information here:
                    "With Ducati Corse now at full ‘attack mode’ in the World Superbike Championship (SBK) in 1989, the 851 Strada received a major update with 17 inch Brembo wheels, although losing its superb Brembo floating discs. In 1990 the Strada received a dual seat a Showa front fork and ضhlins rear suspension."

                    You lil' beauty! The Showa fork they are referring to is a basic USD fork fitted to a few bikes including 900SS and such like that is much more affordable and easily up-spec'd with modern cartridges...and if it was available for the 1990 year it would have been physically produced and available for sale towards the end of 1989. That'll do me. So some relatively cheap Showa forks were sourced and my friendly Ohlins tech (great bloke, very helpful both in the workshop and trackside) came to the party with a quality alternative to Ohlins cartridges without the Ohlins price tag. While he was at it he rebuilt and fitted modern valving and hydraulic preload adjuster to the OEM Ohlins shock.

                    Showa's, note the looooong fork bottoms typical of the early USD forks:

                    So I order a set of 900SS triples like this, which bolt straight in:

                    Only this is what actually rocks up:

                    Monster triples! Close though...ok, maybe not, but it was sorted eventually so only a bit of time lost.

                    The front guard is a totally different mounting with this set up and it makes for a good excuse to bin (not quite, but close) the ugly original unit and replace it with an aluminium one......

           of course it's carbon:

                    Righto, after turning up some new ally spacers to replace the speedo drive (yes, fuel injected bike with a cable driven speedo, it does my head in too) the front end is pretty much sorted. Geez, that only took a year or so, with 7/8ths of the bike remaining I should be done in.......about 2023. Sigh....
                    Last edited by slowpoke; 01-08-2017, 11:27 PM.


                    • #11
                      Can't wait..2023 you say??? / I might be dead / don't let that stop you......(you'd wanna fkn win a race ...somewhere..PF freeway..'ll do) NOW GET ON WITH IT>>>>!
                      " Imagination is the seed of life..."


                      • #12
                        Originally posted by GsxInShed View Post
                        Can't wait..2023 you say??? / I might be dead / don't let that stop you......(you'd wanna fkn win a race ...somewhere..PF freeway..'ll do) NOW GET ON WITH IT>>>>!
                        Haha, righto then!

                        I mentioned the speedo was mechanical drive? The tacho is also, driven by cable off one of the cams. The Magneti Marelli "P7" ECU, developed in conjunction with Ferrari and a few others ain't too smart! To get decent tuneability and the ability to drive an electronic tacho you need the up-spec "P8", from the Sport Production models. It's a good ECU though, used for quite a few years on later model 916's right up to WSB level, and has the facility to tune each cylinder separately, can run two injectors/cylinder etc. Tuning was both tricky and dead simple. You need to have someone able to adjust ignition and fuelling maps and then burn them onto a chip (tricky) but once you had a chip you just unplugged the old and inserted the new (easy). It's hard to find someone able to tune maps and burn chips these days but there are still plenty of different chips available.

                        Back to the P8 ECU, how to get one for cheap? The "Ducati" P8's go for good money.......but they are also available in a few other bikes like Laverda's (Guzzi's?) and even some cars, so I just picked up an el cheapo Laverda "Ghost" unit for 1/4 the price of a Ducati unit and swapped out the chip. Job done. Hmmm, too easy, too cheap so I made a point of squandering extra cash on a completely unnecessary carbon cover to save about half a butterfly's wing in weight. You idiot....

                        Again, not my bike but it looks much the same:

                        The WSB/BSB and other highly spec'd race spec bikes would have this mounted up front behind the dash, to get a bit more weight over the front wheel (it's a pretty sizeable unit, taking up about 2/3rd's the size of an A4 paper in real estate) rather than keep it in the stock location in the "boot". That's too trick for me though, I'm just happy to have the ECU.

                        And a tacho, ordered from a contact in the UK. The white faced unit I wanted (to match the temp gauge) is a pretty rare thing and this one was as new, which (groan) means it wasn't cheap. How "not cheap"? Just over $400AUD landed in Oz....except it didn't land in Oz and is missing to this day, cunt of a thing. No such luck on a refund this time. This is the actual unit in question so if you see it lying around a Post Office I'd appreciate a shout out....

                        After a few months I gave up and went for the "easy" option of a white face Scitsu instead, it's not bad....but it's not the same. I've fucked off the bulky anti-vibration mount to tidy up the installation, relying on the dash pod anti-vibration mounts instead.

                        On the plus side that long lost carbon airbox finally turned up......4 months late! I couldn't believe it, I was sure some kid in Bangalore had figured out a way fit it to his/her Royal Enfield. Don't worry, I made a point of contacting the seller and refunding his refund, treat people as you'd like to be treated, I reckon.

                        But what to do about the donk? The ol' girl was looking starting to look like mutton dressed up as lamb, all gussied up with a few bits of go-fast-finery, only to have a wrinkly ol' 90hp 851 underneath it all. It just wasn't right.

                        The early desmoquattro's were renowned for being fragile when rev'd hard, they were only an evolution of the old Pantah donk after all which simply wasn't built for 100+ hp or sustained +10krpm. Cracked crank cases were par for the course back in the day, mainly due to the "stressed member" engine, stressed. Apparently Raymond Roche used 36 engines on the way to the 1990 title.

                        Some inspiration came in the form of some online chat about Bob Brown's legendary 851 bike coming up for sale. This is the bike he and Kevin Magee/Robert Holden really made a name for themselves on, regularly smoking even Factory 851's. How? Apart from Magoo's and Holden's talent, Brown thought well outside the box: casting up his own cylinders to make what was 888cc (yes, all the racing 851's start out as 888's, confusing I know) into 1000cc, after finding the fuel injection unreliable he turfed it and fitted 2 x FCR flat slide carbs to each cylinder and fabricated a cutom alternator cover to fit a Krober ignition system etc. It's just a hell of a thing, and an absolute weapon at the time. See below for some pic's:

                        The part that caught my attention, that I thought would help me out, was the extra frame rails he added. Check out a "standard" Corsa race frame below. It has small gussets welded at the section where the frame narrows down (a Strada has no gussets) where Brown has added more triangulation at what to my uneducated eye looks like a perfect "hinge" point. From all accounts it extended case life dramatically by taking some stress off the engine, remembering that the swingarm pivots from the cases alone, with no support, the cases are under a fair old load. Hmmmm, I reckon I can do me some of that......

                        It was about this time I stumbled across a set of 96mm high comp Pistal pistons and barrels (for 926cc, stock 851 is 92mm, are you sensing danger?) and a crashed 748R engine......
                        Last edited by slowpoke; 02-08-2017, 02:38 AM.


                        • #13
                          I had cracks in my monster frame in that area.. welded similar gusset in.

                          I have a titanium front axle that'll fit for sale if you want it!


                          • #14
                            Originally posted by monsta View Post
                            I had cracks in my monster frame in that area.. welded similar gusset in.

                            I have a titanium front axle that'll fit for sale if you want it!
                            Bloody hell, that's like asking an alcoholic "Are you sure you don't want a drink?" Lol.

                            Back to my engine.....the one good thing (there has to be something right?) is the evolutionary nature of the beasts. Basically when you are onto a good thing don't fuck with it too much. Hence folks these days are able to bolt 1198 engines into 748's, 996 ST4S engines into 851's ("must resist...must resist!"), and many many parts within the various 4V engines are interchangeable.

                            A few people have built 648/649 engines that Ducati never did, to compete in lightweight twin classes around the world:

                            "What I ended up with was Ducati 749 pistons in a bored out (+2mm) 748 motor with a mega short-stroke of 51mm from using a 400SS crankshaft."

                            That's 3 different era's involved: old 2V 400, desmoquattro 748 and testastretta 749. It would not have broken the bank to build, and all in a sweet chassis that has SV/ER6 owners crying "Referee!".

                            If you want a lil' more hp and a lot less weight (106hp, 13kg's lighter than stock 4V!) simply add cubic money:

                            So there are innumerable options, but realistically the options are more limited Downunder with parts availability. I'm already realising I could probably build another bike simply from what I will end up spending on shipping various parts for this bloody thing. Also there are some well known "go to" parts that everyone knows are the dog's danglers, and prices are just nuts, like 996SPS cams which you'll pay around $1000 for a used set.

                            But when I saw a crashed 748R engine come up for about the same sort of money as a set of SPS cams I started to get some traction with a way forward. It mightn't be the "ideal" set up but it made a lot of economic sense. I could use the high lift 748R cams, close ratio gearbox, Ti rods, big valves and possibly even the shower injection (in NZ): winna winna chicken dinna!

                            Then I came across the big bore 96mm pistons/barrels, although they had 21mm gudgeons from the early race bikes and the 748R rods were 20mm. Bugger. But things were coming together, albeit not perfectly. FYI, the 888 is just a 2mm bigger bore than the 851 and the Factory bike bikes used the 96mm pistons to get 926cc. To get the classic 955 of the 916 series race bikes, just add a 916 crank with it's 2mm longer stroke.

                            Hmmmm, pity the 851 crank cases have all the structural integrity of your mum's Christmas pavlova...and about the same life expectancy in a race application.

                            It was about this time that everything other than my slow burn bike project went slowly but surely pear shaped.

                            2 family members had passed away in the previous 12 months (the reason we were back in NZ), then one of our closest friends also passed, a house build, and the continuing commute to a remote Oz location for work pretty much did me in. Something had to give. So it was either give up the decent money working FIFO or move back to Oz to make it sustainable. Our rural location was just great for lifestyle (see pic below) but lousy for work so in a way our decision was mad for us: we had to move either way so we decided it would be back to Perth for one last push chasing the dirty dollar.

                            Bye bye:

                            And ain't moving house fun!!!!! Fuck me, forget Guantanamo Bay for terror suspects, just have them move house a few times and they'll soon turn a new leaf.

                            So I had a stash of bits and bobs and the bike half disassembled when the house sold. AAAARGH! I didn't have much option but cobble together whatever I had because Customs needed pics/info of the bike to get import approval, and if nothing else it made it easier to transport. Mutton dressed as lamb? Sheep in wolf's clothing? That about sums it up with some half decent race fairings and a good front end, with a bone stock 851 hiding underneath. It ain't flash but this is what was transported:

                            I'm not a fan of the tinted screen, and the single exhaust was thrown together by a mate just before we left. It isn't quite as we discussed so it's a lil' aesthetically challenged but under the circumstances I wasn't (and am not ) complaining. The fairings included a 888 tail rather than the "fuller figured" original 851 unit I prefer, something else to add to a list that never seems to get any smaller.
                            Last edited by slowpoke; 04-08-2017, 04:43 AM.


                            • #15
                              This has been one of the most interesting threads on PSB in recent memory - you've got a way with words (and bike building).
                              Spiral out, keep going...