S2R Monster - Written Sept ‘05

The newest in the Monster range, being the S4R chassis with the 800 2V engine and some cheaper front brakes.  The cheap front brake thing seems to have really offended some people, but they seem ok to me thus far on the ones I’ve ridden and would probably be all the better for some decent pads anyway, like most of the others.

I’ve had a couple on the dyno, so we’ll start with a Ducati Performance kit of the high mount ‘one muffler on either side’ style.  The S2R kits are coming as mufflers, air filter kit and ECU.  Why they’ve decided to add ECU to the 2V power kits for ’05 I’m not really sure, given they went to great lengths previously to not supply matching ECU.  Maybe they decided they could make more money that way and found that greatly appeasing.

The graph below shows std in green and DP kit fitted in red.  A nice improvement, but not as much as the previous incarnation of the 800 made – I’ll get onto that in a minute.

Now because it’s a question I’ll get asked a lot I ran the mufflers and air filter kit with the std ECU.  Just to see what happened, as the original 800 leaned out quite a lot even with just mufflers fitted.  The graph below shows the above graph with the ‘std ECU’ curve added in blue and the air/fuel traces added.  I wouldn’t read too much into the fact the std ECU made more power other than that it’s a bit leaner and often a short break period ( to swap ECU) when on the dyno will produce slightly better numbers when you start it up again.

The std ECU had the trimmer set on +12 or so from memory – I hadn’t set the mixture before the run – and the DP ECU had the trimmer set at zero, which I had done after the kit fitment.  As a side note here, if you fit a DP ECU for an 800 engine of any kind (and 1000, 749 and 999) you need to do an electronic TPS reset procedure with the Mathesis.  Otherwise the TPS signal will not be referenced correctly by the ECU.  So the std ECU may be artificially rich to some extent due to the higher trimmer setting.  Don’t know, but +12 is not what I would expect from a 2v these days.  So if the trimmer was around zero where I would expect it to be I’d then expect the blue air/fuel trace to move up maybe ½ a number leaner.

Anyway, the graph.  Std in green, DP kit in red, DP kit with std ECU in blue.  There really can’t be too much difference in the WOT fuel lines between the two ECU, as the air/fuel trace is very much the same shape and only a little leaner.  What does intrigue me though is that the curves go as rich as they do with the open airbox lid under 4,000 RPM.  Obviously, even though the airbox lid is open the engine is moving less air than when all std.

Compare this to the graph from the 800 Monster report and you’ll see the change for the s2r is minimal.  Maybe it’s just the cat holding everything back.

Comparing the two models, we’ll start with all std power.  This S2R is green, another all std S2R is blue and the 800M is red.  The 800M certainly makes a bit more through much of the RPM range, and as the only difference is exhaust, that’s realistically all it can be.  At least the consistency between the two std S2R is very good.

Next we’ll compare this S2R (green) with its DP power kit fitted to the 800M (red) with mufflers and air filter kit and +25 points on the trimmer (std ECU) to richen it up.  Which, incidentally, still wasn’t enough.  The 800M has a very clear advantage here, especially in the 6,000 to 8,000 RPM range.

Something else I’ve tried for the S2R is a cat replacement pipe.  I had one made locally for the S4R using a floor stock S2R we had as a model, only to find when I tried to fit it to a S4R that the engine cases are different (I hadn’t thought to look, Doh).  So it doesn’t fit a S4R yet, but we’re working on that and it’s only the horizontal header pipe that needs changing.  The pipe is made from 45mm OD tube, like the std ST4S headers, and sized for the S4R.  I was keen to try it on the S2R, just to see if it lost power and where.  The bike it was fitted to was otherwise std.  Green is all std, red is with the cat replacement pipe.  I’ve added the air/fuel just to show what it’s done where – changes to the air/fuel are a very good indicator of whether or not it’s flowing more or less air and what to expect from tuning to suit.  With the cat replacement you can see it’s flowing more air (leaner) under 5,000 RPM, less in the 5,000 to 6,000 RPM range and more from 6,000 RPM upward.  The dip in the power curve I would expect to be removed somewhat by tuning, but I wouldn’t expect to be able to remove it all.  This was only a quick before/after run for a looksee so no tuning was done.

The owner of this particular bike has an Arrow full system on order and he says the graph on the Arrow website shows a similar thing, albeit to a lesser degree.  I believe the Arrow system is 45mm all through, so I’d expect that.

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