Napolean rode a Ducati?

“Never interrupt your enemy when he is making a mistake.” Napolean Bonaparte.

I have a real love hate relationship with my 851/926: I hate to love it while it loves to hate me. And clearly it has fully embraced Napolean's mantra, such is the delight it seems to take in not cutting me the slightest break.

We've been relocated at our new property going on nearly a year now. What with the work and drama's going into preparing/exiting the old joint and getting set up at the new digs while spending half my time away at work, seat time on anything bar a train, plane or automobile has been virtually non-existent. I think I've charged the battery on my old R1 roadie 4 times and ridden it on one short errand since we relocated, and I haven't done a track day since the early days of Covid. It was a pretty sad realisation.

Something needed to change.

So a commitment was made and a week later I'd tripled my ride tally, albeit no major mileage. But it was a start. Rusty? More like barnacle encrusted, some ugly lump dragged up from a shipwreck, I need to just chip away at it to hopefully/eventually reveal something half decent, but I felt better for it mentally if not physically.

Ultimately, getting back to the track was my main aim and a (don't do it, don't do it!) sneaky squint at the trackday calendar had a date I could make in a couple of weeks time. Gulp! I wasn't ready, the bikes weren't ready, but there's nothing like a deadline to focus your attention. If I was slower than a wet week so be it, it would at least set me on the right path.

There wasn't much i could do about my sad reborn-noob status, cruising around backroads is nothing like track riding unless I wanted to find myself standing in front of a judge, but I hooked into basically recommissioning the 749R: replacing fluids, flushing the brakes/clutch, draining/replacing old/fuel, checking belt tension (replaced prior to last track day), slipper clutch service etc.

I threw in a few freebies, me being a valued client 'n all.

The forced:

The aftermarket pitbike-style tethered killswitch I'd installed had gone guts-up, only found when I started the bike and realised I hadn't even plugged in the toggle/lanyard. This first switch was actually pretty good quality and has lasted 10 years. The second unit on the 851, supposedly identical, was noticeably cheaper construction and I'd already had to make some minor repairs and replace the toggle. So, unbelievably, I was prepared(!), having done my Googles and found something that looked both far better quality and more integrated, this billet alloy solution made by PMR:

As you can see it replaces the brake or clutch perch clamp and is also available with run/start switches if you so desire. I run it on the clutch side with no extra switches required. It's just a quality piece of kit.

The unforced:

While replacing the killswitch I realised the connections were just downstream of a large virtually redundant 12 (?) pin electrical connection I could eliminate. And why not install the smaller/lighter billet run/start start switch I had on standby, to save me reterminating the bulky OEM run/start switch that was already living on borrowed time.

"Superseal" connectors weigh next to nothing, perform well, and comprehensive kits are available online for pennies:

And it all looked fairly Factory once I'd reterminated the switch, and fitted Ergal bolts, for a "whopping" 100gm weight saving:

Another lil' feel good job:

I'd tripped over another 749/999 ergal/7075-T6 alloy rear axle (as previously fitted to the 799RS project) being offered privately for cheap, so I stuffed that in, saving another 0.5kg in unsprung mass.

FYI, lightweight Ti/alloy axles are forbidden under most General Competition Rules including WSB (hence there are no genuine Corse equivalents), but for a trackday the gloves come off.....and being thicker than the steel unit I'm comfortable that the 7075 axle is actually stronger than OEM.

That was a few days work in amongst my various other chores, leaving me just over a week until the trackday. Getting nervous, my jittery hands needed something to do....

...the timing wasn't great but it never is, so I decided to have it out once and for all with the 851: handbags at dawn!

Sheezus, it seems like ancient history now but the last real time we'd been on (barely) speaking terms was after the 2nd "Exxon Valdez Racing Team" incident. I'd discovered the OEM crankase breather box was just an empty box completely devoid of any oil/air separation qualities, and she'd pumped oil mist into the airbox from where it eventually drained/misted out over much of the engine and tyre. While a complete disaster (crash) was avoided there was nothing to celebrate on what was a very bad day at the office.

In response I'd constructed a genuine oil/air separator from carbon fibre, and refitted the PCV valve down at the crankcase rather than RS-style up at the airbox, then tested it as best I could on the dyno.(previously detailed here) And that was where I'd left it.....

....but there were still some major trust issues. Refer below:

She's obviously a redhead and almost certainly a "Tiffany" (Italian => Tiffania?) and abso-fuggin-lootley in the "Danger Zone".

So, promising dyno and leakdown test or not, I'd already decided to tear the thing down and refresh the rings/bores and start from fresh, giving my Franken-breather the best possible chance of success. The head gaskets etc had arrived ages ago so I was just looking for equal parts opportunity and motivation.

Having the top end off the bike also seemed like the perfect opportunity to replace the heavy adjustable steel cam pulleys with a set of 4 adjustable Ergal cam pulleys. 18 tooth alloy pulleys (Desmoquattro are 18T, Testastretta are 20T) are as dear as poison, hence I'd initially made do with steel on a tight budget. But these (used) were surprisingly affordable so I'd snaffled them. A set of 6, including the layshaft pulleys, would have been even betterer gooderer but given the price and weight saving I was a more than happy camper. These are a little unusual for a Ducati:

There are 14 holes in the hub and 15 in the pulley outer so you have a growing mismatch as you progress away from the pin, equivalent to portions of a degree. So with the toothed pulley in position you can rotate/degree the inner hub (keyed to the cam) independently, pick the holes that line up and insert the pin. The cam nut then locks it all in place. Note the pin is M3 female threaded for easy removal via an appropriate fastener. Looking below you can see how the holes get progressively more offset as you move away from the pin:

You are in no-man's land if you are hoping to use OEM parts: you can get adjustable steel pulleys, or non-adjustable alloy pulleys, but there are no OEM adjustable alloy pulleys. Of course you can use offset keys to adjust the timing of the fixed units but you have to find them first which is no easy task. So aftermarket it is.

For comparison this is by far the more common style, basically alloy copies of the OEM adjustable steel pulleys:

Note there is a slight trap here: you'll see my pulleys have a side-rail to guide the belt, where the pulleys above do not, so if you're investigating a purchase make sure you have something somewhere to keep the belt running true.

Before I touch on the process of cam timing, what am I hoping to achieve by adjusting it? Just holding one of each pully in each hand revealed a stark difference:

Now multiply that difference by 4 = 620gm, that's over half a kg of rotating mass. Sure, cam speed is half crank speed but if you're at say 10krpm, that's still 0.62kg mass rotating at 5krpm resisting your efforts to turn the bike, and accelerating that mass consumes hp, hp I'd rather have available at the back wheel.

The other change I wanted to make was the actual cam timing itself. Stock setting is 110/102 deg (inlet/exhaust cam centrelines). I'd initially found a great source who had solid results with 104/108 on a stock 748R (I'm using 748R ported heads/cams on the 926cc bottom end) so that's what I'd gone with. Fast forward a few years and an online buddy had built something similar with 748R heads and 95mm pistons in a beautiful 851SP3 for 907cc. His build exceeded all expectations following a slightly different timing recipe (107/105) and given it was fairly similar to mine it made sense to make the adjustment. (Thanks Jacco!)

Why am I bothering? I wouldn't trust me as far as I can throw me, and I've tried plenty hard to throw myself various places over the years....but I trust Brad Black. He has put in the hard yards to collate a mountain of hard won knowledge. This is why he bothers:

His wealth of knowledge can be found here:

Another expert I have on speed-dial....er, ok make that Youtube subscription, is Nellie at DesmoWerx. Here's a great walk through of measuring cam timing and then adjusting cam timing:

Note, while it sure would be easier/faster, you don't need all the sexy Ducati workshop tools. You'll need some sort of turning tool and degree wheel, neither of which are expensive, but the multitude of dial gauges and mounts/fittings aren't strictly required.

A piston-stop for finding TDC can be made for nothing, or bought for next to nothing, and the methodology is just as accurate as the TDC dial gauge. And this is my uber-simple dial gauge set up, with a bent wire extension down to and (importantly) inline with the valve, mounted on some alloy angle. It's slower, but it's no less accurate and gets the job done:

It's painstaking work, made even more so by my style of pulley, which I'm guessing is why they were priced like cocaine in Colombia. The problem is you run out of hands/fingers/space when making adjustments.

Theoretically desmodromic Ducati's don't need valve springs, which is absolutely true of many race bikes. But if you don't want the thing to stall and generally be a grumpy pig around idle/town, and actually want to sell them as road bikes, you fit light "closer springs" to negate any slight clearance issues with valves closing.

So it goes like this: put the engine into the right position and position the cam for the correct 1.0mm lift, but the closer spring is pressuring the valve rocker which is following the cam lobe, and being on the side of the lobe (just 1mm of lift remember) with spring force on it the rocker effectively tries to stop the cam rotating (hence the race bikes remove the springs, they are a parasitic loss).

This is no issue with the common slot-style pulley's, you loosen the bolts the bare minimum to make the adjustment, maintaining the cam position despite the leverage.

It's a very different story with my style pulley when you have to completely remove the pin, all positioning force is lost and the cam simply spins free, forced by the rocker/spring. The answer is beer, and keep it comin', because your temperature will be elevated and your throat will be dry from a constant stream of profanity at various volumes....and after all a man is not a camel.

So yes, you need to somehow hold the cam in position against spring/rocker pressure (the cam, not the outer pulley), pull the (tiny) pin, then turn the cam to a very specific position. You've probably had to put the (tiny) pin down to accomplish this so you'll have to find/pick up the pin again with long nosed pliers while holding the cam, find the holes that line up, insert the pin.....all while constantly monitoring a dial gauge that could be facing the floor or up against/completely obscured by the rear suspension. Have a tidy up prior because anything you can put a hand on will find itself ejected from the building....

But, eventually you get there....and need to go around collecting all manner of previously hurled objects:

Some random tumbleweeds blowing around in my scone:

- you'll need either a cam locking tool to loosen/tighten the lock nuts or you can just use an old belt and pinch/hold it with vise grips.. There are various styles of tool available, ranging from cheap to "shock and awe". The cam locking tool is also handy (but not mandatory) for belt changes so is probably worth the minimal investment.

- another tool you'll definitely need is a 4 pin socket/tool for the cam nut so it's unfortunate many suppliers seem to have a penchant for making them out of cheese. Admittedly it's hard to tell, but go for the best quality you can find/afford....or make one out of an old socket.

- do your Googles: there are 2 different size cam threads/nuts. Very generally speaking, desmoquattro and earlier 2 valve stuff uses M15, testastretta and later type cams use M17, so have a squiz before you tear into into it.

- note the cam nuts, called "elastic lock rings" in Ducati nomenclature, are supposedly single time use so if you're going to have a crack have them organised prior. There is a bit of trial and error involved, things move (GRRRR!), so I used the old nuts throughout until everything was checked and re-checked and only then did I fit the new nuts/washers.

- you have a decision to make re Loctite on the cam nut threads: in the 851 manual Ducati recommend nothing be used on the threads, the 749R and 999RS manuals both recommend grease, where many workshops and experienced engine builders use a drop of "Blue" Loctite. This is where the quality of that 4 pin socket comes into play: cheese socket vs Loctited cam nut? My money is on the cam nut winning that battle.

After giving my frown-lines a solid workout it was time to relax and put it all back together, fill it with 15w-40 mineral oil, mineral for breaking in the fresh bores/rings, and.....pause. Go over the bike. Mentally disassemble... reassemble...torque....belt tension....etc etc 'cos you really, I mean really, don't want to get this far and not just ruin your work but the whole top end.

All good? Take a deep breathe, clench sphincter, and hit the starter button.....

.....no reason it shouldn't have...ok, lotsa reasons it shouldn't have, but that moment when it fires into a lovely smooth idle, is just pure gold and....dammit, she's hooked me again!

Yes, it's been a while but the timing change has definitely improved the idle and it does feel a smidge more crisp, not sure if that's the lighter pulleys, the cam timing, or just my brain making shit up to protect itself.

But allegedly a similar bike was seen/heard on backroads in the vicinity, and whispers around the neighbourhood are that after a few km's of touring through the rev range, that it went plenty hard right up to redline.....wow, what are the odds of another close by? (don't make eye contact....don't make eye contact...) 

With that, there was nothing left but to make the ol' girl's presentable ready for a day out, a rub 'n tub removing a year's worth of dust and grot accumulated in a poorly sealed shed:

Oh yeah, if you look closely above you'll see I updated the front calipers a while back. That last track day, many moons ago, dissolved my delusion that the OEM front brakes were "adequate, just needing a firm squeeze".....nup, in the cold hard light of a pretty shit day I'd realised they were just crap. In theory the cast iron discs and appropriate Brembo pads should have been pretty damn good....but in reality were the most antiquated feeling of the whole bike, like the neck of a woman post face-lift this was the one area that really gave its age away.

But amongst a small package deal of good and not so-good parts were a set of Brembo 4P billet 30/34 GP calipers, these falling somewhere in the middle of the range being pretty ratty (the heads of the stainless bolts on the RH caliper have been tapered with a drill and file to mimic titanium bolts).

But a refurb, new pins/clips (the RH caliper had none), and some Ti bolts had them as good as they'd ever be. I experimented with a couple of different master cylinder ratios to get the best feel I could, and pads bedded in, but this would be their first real test..

With that I just needed to dress 'em up, pack 'em up and head to the track....