Cam Timing – Settings and Effects of Changes - Written Nov ‘04
4V models

A foreword of sorts:  all this is just my opinion, from my results.  Yours or others may vary.  My acquired status as an internet expert does not mean I am one in any way, shape or form, or that I want to be one.  As Doug said once, an expert is “someone from out of town”.  For many of you I’m on the other side of the world.  You are under no obligation to believe me.

There are a few comments along the way talking about the feel of a result.  These can be important.  All the graphs shown are taken from the reports on each specific model - if you want more info that’s where to head.

And if you want to know for yourself, you can always experiment.  It only costs you time and money after all.  I waste quite a bit of both.

Update March ’07 – the intro from the 2V report has been added, to help it make a bit more sense.

One question that I get asked a lot is “what cam timing do you recommend?”  These days I tend to just tell people as it doesn’t really matter that much to me anymore to keep things a secret.  Except for locally I guess, but even then I’m not really that worried.  Mainly because saying “I won’t tell you, but we’ll do the job for you” just gets me whined at.

There are two main reasons for this.

  1. The settings I use are what I have chosen.  That doesn’t make them the ultimate or the last word or the best for all applications.  It’s just what I use.  I’m no expert, just as guy who wastes a fair amount of time screwing with bikes. Ask your local tuner what he recommends and I’d be very surprised if you got the same answer.
  2. If you run timing like I use on the injected bikes you’ll need mapping mods to get the best out of it.

This is a point I try to push because I see tuning things as the final step.  Many don’t bother, which really annoys me in the short term, but just disappoints me overall.  I see quite a few badly tuned bikes and knowing they could be better if the owner just let someone with the right equipment and knowledge at it kind of bugs me.  The fact many of them have a box of inappropriate eproms they persist with highlights the misunderstanding of the whole tuning thing.  This is something that really gets Doug wound up.  But, I can’t save everyone and they’re only motorbikes anyway. 

So, I’ll go through this report given the specs I’ve tried and what I have decided on using and why and why it might not work for you and fuelling changes required.  But first I’ll start with a short discussion of cam timing and what does what.

The way I talk cam timing, as do most people, is in terms of centreline.  The centreline of the cam is the theoretical centre point between the opening and closing points at the chosen lift related to TDC (overlap, or the end of exhaust/start of inlet stroke).  The lift used to express centreline cam be important if a cam isn’t symmetrical – the centreline at 0.10mm lift may be different to the centreline at 1.00mm lift.  This is why there are now accepted standards for these things. 

Generally, all the Ducati specs are given at 1.00mm lift.  Some of the manuals – late ‘80s, early ‘90s 2V mainly - list both 0.20mm and 1.00mm timing.  But the later ones use 1.00mm, and it’s a figure that’s a bit easier to use I find.  If you come from anything based on American V8s you’ll be used to reading “50 thou lift” (1.25mm).  Using this range of lift figures gets you away from the opening ramps which may confuse the process – the old std was “advertised duration” which itself varied around the 0.006” or 0.15mm lift spec and generally made comparing various cams very difficult.  What spec you use is up to you – I always use 1.00mm lift but I never worry about the valve clearance.  So the numbers I get are always a little on the inside of the specs.

So you need to remember the centreline is a mathematical thing that exists only on paper.  If you go looking for the centreline you’ll have a lot of trouble finding it.  And it bears no relation to the max lift point.  If the cam is symmetrical it should be the same, but many cams aren’t symmetrical.  To calculate a centreline you use the following formula, set out in steps.

Inlet:

  1. Inlet opening (IO) + inlet closing (IC) + 180 = duration
  2. Duration / 2 = half duration
  3. Half duration – IO = centreline

Exhaust:

  1. Exhaust opening (EO) + Exhaust closing (EC) + 180 = duration
  2. Duration / 2 = half duration
  3. Half duration – EC = centreline

For a 916 with cam timing specs of 11/70 inlet, 62/18 exhaust we get

11 + 70 + 180 = 261
261 / 2 = 130.5
130.5 – 11 = 119.5 Inlet centreline

and

62 + 18 + 180 = 260
260 / 2 = 130
130 – 18 = 112 Exhaust centreline

So, the centrelines are 119.5 degrees ATDC (overlap) for the inlet and 112 degrees BTDC (overlap) for the exhaust.  Not max lift points, just the theoretical centreline based on the opening and closing numbers.  It doesn’t tell us anything about the actual cam profile, but is very useful in expressing what’s happening where.  If you don’t want to use centrelines you don’t have too.

The next bit I need to cover is what numbers we are paying attention to.  The most important number is inlet closing (IC).  On a single cam engine, inlet closing is what governs where the cams goes, thereby dictating IO, EO and EC as well.  On a twin cam engine EO and EC can do their own thing.  As IC sets IO, you can move the exhaust cam around to get the sort of overlap you want (EC and IO), but I don’t really do that so much – I’ll get onto why later.  I tend to ignore IC these days, looking at centreline instead, something that caught me out somewhat when playing with the 1000SS ds ie.

When you move the cams around you either advance or retard them.  Advance means they open and close earlier in the cycle, retard means they open and close later.  In number terms, advancing the inlet makes the centreline number smaller, whereas on the exhaust it makes the number bigger.  Conversely, retarding the inlet makes the centreline number bigger and the exhaust number smaller.  Advancing an inlet cam will also reduce the piston to valve clearance – tightest usually from 5 to 15 degree ATDC inlet opening (overlap), whereas retarding the exhaust cam will reduce the piston to valve clearance – tightest usually from 15 to 5 degrees BTDC exhaust closing (overlap).  To increase piston to valve clearance you retard inlets or advance exhausts.

So if you see cam timing specs with large inlet and exhaust centrelines there may be a piston to valve clearance issue behind the settings.

Next - a generalisation.  Advancing the inlets gives more midrange and less top end (therefore implying retarding the inlets gives less midrange and more top end).

This one is a real favourite.  It is basically true, but assumes something that turns out be incorrect for some Ducatis.  That is, the std cam duration and settings are the best possible (some people like to use the word optimum, which to me infers perfection or delusions there of.  I prefer ‘desired’).  They aren’t.  The duration of the 4V Strada cams is a bit too long (and they’re under valved), and the std settings can be improved upon.  Add to that the fact the “as fitted” timing is not that accurate and there is obvious room for improvement.

This is changing though.  The engine updates and revisions from Ducati in the last few years – starting with 996SPS in ’97, 748R in ’00, S4 and ST4S in ’01 and now onto the Testastretta and 620/800/1000 2V updates – in the intake (or breathing) area have all been about bigger valves (except S4 and ST4S which carry the usual 916 and 996 valves) and shorter cams.  With good results.  Some engines have made the same power with less cam duration (998/999 and ST4S compared to 996) or made more with the same duration and bigger valves.  Compare the 748R to the 748Strada, the 998S to the 996SPS, 749 to 748 or any of the 600/750/900 to the respective 620/800/1000.  All the reports for these models give specs that show what’s changed.

So the relatively easy power increases we’ve seen in the older models through cam timing changes are now often not there to be had.

One thing I thought about long after I’d written these cam timing reports initially (and removed and sold the 600 engine even in my Monster) was how my 600M felt a bit rough down low compared to others, and how it seemed happier on premium unleaded fuel.  Being a tight arse the idea of putting premium in it all the time really upset me, but it definitely did smooth it out.  Given the 600 has the 400 engine heads, the combustion chambers are rather small.  To compensate for this somewhat, the 600 pistons have bowls in the crowns to lower the compression a bit, although it’s still quoted at 10.7:1, whereas the 750 and 900 were 9.2 – 9.5:1.

So recently I got to thinking about it (prompted by a question someone asked) and realised that the cam timing I was running would most likely have been causing it, combined with the single step ignition system the carbed 2V bikes run.  The question that prompted this came from someone who had a high comp or big bore 750 2V that was pinging.  He had been recommended by someone else to fit the longer duration 900 carb cams to reduce lower RPM cylinder pressure, thereby reducing or stopping the pinging.

So here’s another factor to think of with cam timing – in very general terms what we’re doing when we advance the inlet cam timing (considering the basic air pump concept) is raising the cylinder pressure at any RPM under the torque peak RPM and lowering the cylinder pressure at any RPM above the torque peak RPM.  Now if you already have too much cylinder pressure for your given chamber shape, ignition advance or fuel rating to handle, then advancing the cams is a backward step in that regard.

And the opposite is also true – you can reduce cylinder pressure at any RPM under the torque peak RPM by retarding the inlet cam timing.  But, keep in mind you may not always raise the cylinder pressure at any RPM above the torque peak RPM by retarding the inlet cam timing – that’s also very influenced by the air flow potential of the cylinder head.

Another point.  The better the heads, the less cam duration or more advance you can run before you start losing top end.  Sort of inferred from the above, but better pointed out too.  Good heads (not necessarily big valves) and shorter cams work better overall than bad heads and big cams (the old way).  Bad heads encompasses small valve heads, not that small means bad, just bad for the application.  851SP3/4 being a good case in point.  Results like this one  http://www.visi.com/~moperfserv/joe_lee_872.htm  of a 748 with 95mm bore (872cc) Bruce Myers built with 996SPS cams and std 33/29 valve sizes in well ported heads really prove this.  Simple yet very effective.

Torque curve shape is another thing that many people don’t understand, especially how it relates to how a bike feels in use.  On my 888 I ended up with a very flat torque curve (and smooth power curve) that was not overly exciting to ride, but made for good performance and acceleration from any RPM.  On a 748 a flat torque curve takes away the top end rush that the model has std, something an owner might not want.  It’ll be faster through the midrange, but won’t feel like it did before when it came on at the top end.  Whether or not this is important is up to the owner.  There’s no right or wrong in all this – it just depends how you like it.

There’s a well known Australian tuner who has a trick of changing the Tacho drive ratio electronically on some of the 4V race bikes he prepares, simply to fool the rider into thinking they are using more revs than before.  It’s a mental tune up on the rider, nothing more, but many will report better performance because of it.  The main results are much better engine reliability / lower service requirements, simply because they aren’t revving as hard.  And it’s a very good example of how sometimes you can make bikes go faster without doing anything to them.

Camshaft Selection: For the Desmoquattro 4V (748, 851, 888, 916, S4, ST4, ST4S, S4R and 996) there are 6 original fitment inlet cams – Strada, 851SP (A), 888SP5/916SP (G), S4/ST4S/S4R, 748SP and 996SPS - plus maybe 4 other ‘Corse’ race cams – 431, 450, 453, 458.  The original 748R and RS inlet cams are unique due to the valve spacing (and therefore lobe spacing) being different to get the 36mm inlet valves in the 748’s 88mm bore.  All the 851 and 888 cams (including SP2/3/4/5) have a tacho drive snout on the LH end of the horizontal cylinder inlet cam, so they too are unique to them.  The 888SP5 had G inlets, as did the 916SP, so they come with tacho drive and without.  Although SP5 inlets could well be NLA by now.

The factory exhaust cams come in 6 grinds – Strada, 996SPS, A, G (Corse only), 748R and 748RS.  The 748R/RS exhaust cams have the same valve spacing as the other exhaust cams.

Vee Two offer massaged duplicates of the 748SP, Corse 431, 996SPS and 748R (with normal valve spacing) inlet cams and the G, 996SPS and 748R exhaust cams.  Plus another inlet (603) that’s very big and probably eats valve train bits for dinner.

Epicycle offer 2 different inlet and exhaust grinds as 3 performance combinations.  These have profiles developed by Epicycle, making them one of the very few suppliers to do so.

Schrick (a German company) also offer a set of cams for the 4V, but I’ve never had anything to do with them.  They are short duration and high lift like the later SPS and R cams so I imagine they’d work comparatively well.  Cams with the same specs are also marketed by Italian company MSD.

For the Testastretta models there are quite a few different cams, although that’s mainly due to the fact that many are unique, simply due to valve spacing.  The 749 base model and S run the narrowest valve spacing – the 749 inlet cam runs the same spacing as the 999 exhaust cam (probably using the same blanks).  The 749R I believe has wider spaced inlet valves and maybe exhausts also.  It may be the same as a 999, but I haven’t had a 749R valve cover off yet. 

The 999, 999S and 999R ’03 run the same valve spacing (common to the 996R, 998 and 998S also).  The 999R ’05 model runs wider inlet spacing I believe, but again I haven’t seen inside one yet.  The 998RS cams fit the 996R, 998, 998S, 999 and 999S engines, but the 999RS (or F04 as they call them) cams may share the new 999R spacing.  The 999R ’05 is mainly a US AMA homologation special it seems (tighter rules than the SBK world series), so it would make sense the heads are 999 Corse spec.

So what actually fits what I’m not overly sure as yet.  Fitting 998RS cams to a 998S or 999S brings issues with rocker clearance to valve guides as well, in addition to drastically shortened service intervals, so there are some good reasons to not fit them to a road engine.  Apart from that the S cams appear to be a very good piece of gear for most applications anyway.

All this means that the cam selection is not huge, especially when it comes to cam grinds you’d actually want to use.  Add to that the cost of four of them (and their uniqueness in terms of developing and grinding the corresponding opening and closing profiles) and re-shimming which means swapping cams gets pricey very quickly.

This is the main reason I went looking for low cost mods that worked in the first place.  And, for the 4V models especially, Ducati handed us an easy one.

For this report you’ll see cam timing expressed as 119.5/112 for example.  Another centreline convention, it is inlet centreline/exhaust centreline.

I’ll start with the Desmoquattro, going through the capacities. 

When we first started playing with cam timing we ran the std centreline specs of 119.5 inlet and 112 exhaust.  Then we started advancing the inlets, trying 116 degrees then 114 and finally ended up at 108.  I sort of jumped from 114/112 settings to 108/108 with one of the 996 I did and the results convinced me that that was good.  Most models have enough piston to valve clearance to go further – 916 appears to have the most – but I feel that’s probably a bit too much. 

The other point is that when you do a job like this you often need to show the owner a before and after dyno curve.  And as irrelevant as it usually is, any loss of peak power is seen as a bad result.  Just because.  If you go further than 108, especially on 33mm inlet valve 916, you start to lose power at the top end.  Not that anyone would really notice it on the road, but on the dyno it shows. 

Plus there seems to be a point after which the return is somewhat diminished, and 108 is about it from my experience.  Really, there’s not much difference between 108 and 110 inlet centreline, even 108 and 112.  The main point being there is a big difference between ‘as delivered’ settings like 126 and the spec of 119.5 and a big difference again between 119.5 and 112 or 108.  Although, in general, there’s no more peak power in it, just power up to the peak.

One other point – I’m told running 100/102 timing makes them idle really bad.  Never tried it myself.  108/108 really doesn’t seem to make much difference.  It’s certainly never been commented on.

If you want to read a good article about 996 cam timing experimentation then check out Doug’s - http://www.visi.com/~moperfserv/thetest.htm

So I use 108/108 on all the Strada cammed 4V.  But you need more midrange fuel – I usually zone in an additional 15 to 20% to the Ultimap (FIM) eprom.  I’m really pushing the tuning side of it with the 4V engines.  I’m not sure if running this sort of cam timing without tuning will cause you engine damage, but it may.  I’m yet to see anyone melt one of these through bad tuning, but it will certainly not be offering its best.  We’ll go through some before/afters and tuning to show this.  First the specs.

 

I O

I C

E O

E C

DURATION

CENTRELINE

IN

EXH

INLET

EXH

STRADA SPEC

11

70

62

18

261

260

119.5

112

108/108

22

58

58

22

261

260

108

108

First up, a 748.  From the 748 report - the bike with the Arrow 45/50mm half system and Ultimap UM211 eprom.  Green is as was, blue is cam timing at 108/108 without fuel added, red is +10% fuel overall, yellow is +15% fuel overall.

Zooming in on the torque curve gives a much clearer look at the fuelling changes required.  We’ll add another line – pink – which is +5.4% fuel overall.  You can see the torque peaks where more fuel is obviously required: 3,500 RPM, 7,000 RPM, 8,500 RPM – and where less fuel is required: 5,000 RPM and over 10,500 RPM.  If you had the capacity to change all the map points you’d do so, but with the zone ability of the Ultimap software you do what you can.  It’s very uncommon to see a point at 5,000 RPM that needs to be leaner – this 748 is one of a few and I’m quite sure it has to do with the 45/50mm half system. 

Given I add about 5% more fuel than is required for max dyno power I would have run this bike at +17 to +20% up to 10,500 or so RPM (depending on the RPM break points available) and then at +5.4% from 10,500 RPM up.

Another 748 is shown in the next graph, just after runs with fuelling changes.  This one has 45mm Termi mufflers and a UM211 eprom.  Green is cam timing at 108/108, pink is overall fuel +5.4%, blue is +10% and red is +15%.  This one wants more fuel up until about 10,500 RPM again, but there’s no rich induced dip at 5,000 like the previous bike.

748R – I don’t have any direct before and afters for 748R.  The ones we have done so far have all included bored throttle bodies to remove the FIM 44mm WSS restrictor and extended inlet trumpets.  And we’ve then developed custom eproms to suit from there.  So see the 748R reports for the info and graphs we’ve published thus far.  The table below shows the std timing, the 748RS timing and what we run, being 104/108.  Bear in mind the 748R inlet cams have the same duration as a Strada cam and it shows just how little duration it takes to make power at high RPM with these engines when you’re running decent sized valves.  The longer exhaust duration may help here too – something I’m yet to try in other models.  This is also the only engine we’ve ever advanced the exhaust cams on.

 

I O

I C

E O

E C

DURATION

CENTRELINE

IN

EXH

INLET

EXHAUST

748 R

20

60

62

38

260

280

110

102

104/108

26

54

68

32

260

280

104

108

748 RS

30

62

74

38

272

292

106

108

851 – my toy.  I reset the cam timing on my 851 to std spec (119.5/112) when I had the engine out to paint the frame just after I bought the bike, so that’s where I started.  As it was delivered, the inlets were retarded 8 and 10 degrees from the std specs from memory, the exhaust 7 and 4 – something like that.  So it would have been around 128/107 originally.  I then reset it to 108/108 after I’d done quite a bit of exhaust dyno work.  The afters were done only with the ST4 exhaust fitted.  There is no RPM pickup for many of the 851 runs, so I’ll run them all versus road speed.  The same back tyre was used for all the tests, and it’s slowly dying from lack of interest – about 3,000km in 3 years.

Green is before - cam timing on spec (119.5/112), ST4 exhaust, Staintune mufflers, open airbox lid with paper filter and UM011 eprom.  The dip between 85 and 95 km/h is due to it being a bit lean there, +5.4% fixed that.  Pink is cam timing at 108/108, blue is overall fuel +5.4%, red is +10% and yellow is +15%.  You can see how much it likes more fuel in the 75 – 110 km/h range and that it needs at least +5.4% through the whole RPM range. 

As the P7 ECU in my bike has an FIM Additional Memory Board fitted making changes at each RPM and Throttle break point is possible.  So I could add 5.4% here and 10% or 15% there without being restricted to 3 zones as all the adjustable eproms are.  After I did these runs I pulled the injectors and had them cleaned, which added about 3% or so to the fuel flow I’d say, based on the results from the next set of runs I did.  So that’s something else to consider when tuning a bike.

Also you can see that although the power peaks a little earlier and at about the same number it falls away a bit faster.  170 km/h is just under 9,000 RPM.  This 851 is one of the early 32/28mm valve bikes, and the lack of airflow due to the smaller valves hurts the top end.  With better heads this bike would be capable of at least 110 hp I’d expect with these cams at this setting.

Another issue with the 851 in particular comes from the soft valve closing springs and P7 ECU, and is exaggerated by the light flywheel I have fitted.  The 851 don’t idle that well std, and with 16 degrees more overlap - the time both valves are open at TDC at the end of the exhaust stroke/start of the inlet stroke - than spec (and probably 26 degrees more than it was delivered with) the idle is now rather poor with lots of hydrocarbons.  That ‘make your eyes water’ sort of idle.

The light flywheel contributes to this as the P7 (and P8) ECU use two pick ups to sense engine rotation – one reading the flywheel every 90 degrees and one reading the timing shaft (1/2 crank speed) once per cycle for cycle position.  So as the engine comes up to TDC compression and the gas forces slow the piston down, the ECU has no way of reading this like the later single pick up bikes do, as it only gets a signal of engine rotational speed every 90 degrees.

The single pick up ECU – 1.6M, 1.5M and 5.9M - use the timing gear teeth for triggers, meaning they get a signal every 18 degrees.  So my 851 has more valve overlap than std, more crank speed variation at low speed and poor valve sealing at low cylinder pressures.  All of which causes a very rumpity 1,500 or so RPM idle.  Something to be aware of when playing with cam timing!  Although, with the heavier closing springs introduced around ’91 (with the 851SP3’s 33mm inlet valves) it will be much better.

888 - another one of my bikes.  I did this job with offset keys and the timing ended up more like 110/110 than 108/108 - no bother.  The runs shown are with std mufflers, as I had to use different mufflers for the after testing (Megacycle) to the before (Staintune) and the Megacycles seem to give more bottom end, skewing the results somewhat.  Green is before - cam timing as delivered (approx 130/106 from memory), std exhaust and mufflers, open airbox lid with paper filter and FIM DAM Megazone (std map, but adjustable) eprom.  Pink is cam timing at 110/110, blue is overall fuel +5.4%, red is +10% and yellow is +15%. 

You can see that it made max power with +10% for most of the range up to 8,000 RPM, then was happy without any extra fuel after that.  This is the most common fuelling requirement result, and is due simply to the advanced inlet cams trapping more air through the midrange, but not at the top end.  This sort of modification is easy using the FIM zone system – the zones usually work very well for cam timing mods. 

The peak power RPM has come down by maybe 200 while it has 1 to 2 more hp at the peak.  The power falls away at about the same rate as before, so it should be fairly clear that, although we’ve moved the inlet cams by 20 or so degrees there’s been no loss of top end power, which will probably surprise many.  The 1mm bigger valves (33/29) as compared to the 851 help here.  Again, even better heads would show more top end with the same midrange.  And, even though it runs a P8 ECU, there were no idle problems with this one.

916 – there’s no point me repeating graphs here – I’ll just tell you about the 916 report and you can go look at that.  The second graph in that report shows a bike that had the timing set to 116/112, with the fuelling increased by 4% through the whole RPM range.  On the road we ran it at about +9%.  I imagine the std timing on that one was around 125/107 or so.

The one new graph I will put up is for a 916 that we ran at 106/112 timing.  I don’t have any relevant before runs for this bike as the gearing was changed and the after runs are road speed only.  This bike needed a lot more midrange fuel – I knew what to expect as I’d previously set it up on the road – to give the max power.  Green is after with base fuel, pink is overall fuel +10%, blue is +15%, red is +20%.  I’m not sure if the 106 inlet centreline has hurt the top end power at all, but the owner, who was using this as a track bike at the time, thought the power all through the rev range was just fine.  

S4, ST4S, S4R  - with the shorter inlet cams and the normal Strada exhaust.  Never done an S4, surprisingly enough.  Although, I have been told they vary from not too far off to quite a way.  The usual, in other words.  We’ve done ST4S to std spec (the “ST4S with U59” report) and recently an S4R.  The specs for these cams are shown below, along with what we ran on the S4R, which seemed to work just fine.  The 113/110 gives the same inlet closing point of 58 degrees as the Strada cams at 108.

 

I O

I C

E O

E C

DURATION

CENTRELINE

IN

EXH

INLET

EXHAUST

SPEC

11

60

62

18

251

260

114.5

112

113/110

13

58

60

20

251

260

113

110

See the S4R report for all the info there.

996 – we’ve used a few different specs for 996.  The first one we did I ran at 114/112, and that worked very well indeed.  The first graph shows before and after for that bike.  Green is before - cam timing as was, Termi mufflers and Ultimap UM191 eprom.  Pink is cam timing at 114/112, blue is overall fuel +4.6% and red is +8.5%.

The next one we did was the shop demo, and this was the first bike I tried 108/108 on.  It worked better than the previous one, so I figured 108/108 was about as good as it was going to get.  Although the fuelling requirements were somewhat different.  This bike was a bit stronger than the previous one in ‘std with Termis and UM191’ trim too.  Green is before - cam timing as was, Termi mufflers and Ultimap UM191 eprom.  Pink is cam timing at 108/108, blue is overall fuel +5.4%, red is +10%  and yellow is +15%.  This was the first one I’d done to really need differential zoning: +15% in the mid range, then +10% and finally +5.4% at the top end.  And it’s just started to lose power at the very top of the RPM range – over 9.700 RPM.  I like to see this as it means I’ve gone far enough, but not too far – an easy indicator really.  Nothing you’d notice though.

With the UM222 single injector eprom I usually find they need +15 or 20% up to about 6,500 RPM then zero or 5.4% at the most from there to the rev limiter.  Which is a little different to what the dual injector set up requires, but that’s just how it is.

996SPS – I was rather surprised when I first saw the 916SPS (as they were then) cam specs with the fairly late inlet centreline.  The older SP cams had all been long duration things with the inlet closing consistently around 70 degrees so they had inlet centrelines around 100 degrees or less.  The SPS spec of 119.5 was unexpected, as was the increase in duration of only 6 degrees over the Strada.  But they worked very well indeed, so we didn’t complain.

After talking to a few people as to what was worth trying, I advanced the inlets as far as I could on one bike I was playing with while maintaining 1.5mm piston to valve clearance, which got me to 103 degree inlet centreline.  I figured the exhaust spec of 107 was fairly good so I left them there.  When I dyno’d it the result was good.  After we’d done a few it became apparent that the original setting of 103 was a touch too far, as most bikes seemed to go below 1.5mm p-v around 105 degrees.  So we settled on 105-106 inlet, 107 exhaust centrelines for the SPS cams.  As the 996 Strada uses the same pistons and heads these settings also apply to them when you fit the SPS cams.  The 996S ’01 model – the dual seat SPS – that we tested at Duane’s was also pretty tight on the inlet p-v, so we ran it at 107/107.  That’s the timing the UM239 eprom is mapped for.  The UM239 is a 1.6M ECU eprom.  The UM179 is the SPS P8 ECU eprom for this cam timing that I developed.  On reflection now it may be a bit rich at WOT, but it does work rather well.

So if you go back and look at the 916/996SPS or 996S reports, that’s the timing they were running.  The table below shows how that compares to std and to the Strada at 108/108.

 

I O

I C

E O

E C

DURATION

CENTRELINE

IN

EXH

INLET

EXHAUST

996SPS

14

73

57

23

267

260

119.5

107

996SPS 105/107

28

59

57

23

267

260

105

107

STRADA 108/108

22

58

58

22

261

260

108

108

As you can see, the SPS timing ends up pretty similar to the Strada timing we use, apart from the inlet opening.

Testastrettawe’ll start with the 749S ’04 model.  We’ve changed the cam timing on quite a few based on service information with regard to stalling on overrun and at idle.  The change is to open the lobe separation a little - or decrease the overlap.  This is the only timing spec I will ever use on these engines simply to not cause myself trouble.  The table below shows the changes (as does the cam specs report).

CAM

I O

I C

E O

E C

DURATION

CENTRELINE

IN

EXH

INLET

EXHAUST

749S '04

23

55

62

24

258

266

106

109

REVISED

21

57

66

20

258

266

108

113

The change is only a total of 6 degrees less overlap, but it seems to work very well.  Given how much I move some of the other cams with no noticeable idle changes I don’t really understand it, but there you go.

749 and 999 Due to the short duration the new base model engine cams have – the 749 has the same profiles, but the inlet is advanced 10 degrees as compared to the 999 – I don’t see any benefit moving the cams around that much.  We’ve checked a few base model Testastretta engines so far and the as delivered timing seems pretty good.  You could maybe advance the inlets a degree or two and retard the exhaust similarly, but I wouldn’t be getting too carried away.  These engines are very nice things as std – big valves in good heads (Bruce Meyers says the 749 heads flow better than the old 996 heads) and short cams.  The 749 makes great power all through the RPM range and the inlet timing is already 15/46!  That’s very early closing, and only 240 degrees total duration.  56 degrees less duration than a 748SP!  It’d be interesting to see just how short they could go on duration before they lost top end.

998S (also 996R and 999S) – all the 998cc S spec Testastretta we’ve done have been done to the same specs.  We were told at our training in Italy that the S cams were generally all retarded about 6 degree as delivered.  Why they weren’t really sure, but that’s the way it was going to stay.  Given they’d just gone to adjustable pullies it made very little sense that they couldn’t get it right, but (again) there you go.  The first one I checked was pretty close to 6 degrees retarded on all 4.  Later ones have varied between 4 and 7 I guess.

The first one I did I decided to run at 107/107.  As delivered it was around 117/107, so I ended up advancing the inlets about 10 degrees and leaving the exhausts untouched.  I ran this timing mainly because of the success I’d had with the older engines at similar timing and the similarities in cam duration.  Some time later I was told Ducati were recommending, for the Superstock production racing class in Europe, to advance the inlets 4 degrees and retard the exhaust 4 degrees.  This gives 108/107.  So I was pretty close - I was actually quite impressed with myself.

The 107/107 gives a strong midrange improvement without a top end penalty, so that’s about the best I can hope for.  I haven’t tried any other settings simply because I don’t usually get the chance to play without constraints (someone has to pay for it!) and the first result was so good.  If you go the 998S report or any of the 999S reports the before/afters there are for this cam timing.  We have a map for the Ultimap U59 ECU to suit 998S with this timing, and Duane will be testing a 999S we have done also for his U59 ECU.

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