Ducati 888 SP4

The model after the 851 SP3, this was the first model badged as an 888, and is a 1992 model. It also came after another win in the Superbike World Championship ( maybe Doug Polen’s first? ) so had a big "1" on the side fairing. Surprisingly, given the fitment of the extra trick 2 piece MARVIC wheels to the 900 Superlight, it still had the standard issue wheels. Same OHLINS suspension front and rear though.

First up is a graph


Dynograph courtesy of DYNOBIKE (03) 9553 0018

A pretty nice result you might think. Only thing is, it’s not before and after. The red line is the base, or standard, run for the 851 SP3 featured in another report. The green line is the base run for this particular 888 SP4. Given that these two bikes are mechanically supposedly identical, with the same cams, inlet, exhaust, valves, etc, I found this quite odd. The difference is not small, with at least 6 Hp variation from 6,500 RPM on. Not much I could do about it, as the SP4 had good compression and seemed otherwise very healthy. The owner was the man who bought it brand new too, so we knew the history also.

Given this was what I had to work with, I went ahead. The cams in these engines have very similar timing numbers to the 748 SP/SPS cams. As far as I can tell, the exhaust cams are the same grind, known either as A or K or the original 851 Tricolour race kit cams. The inlets run almost the same opening/closing figures as the later 748 SP/SPS, but with around 1 mm less lift. This would make sense, given a natural progression in cam design is to increase the lift. Given this, I chose to set the cams around the figures the Ducati Dealer Team had run their 748 SPS bike at. Might as well use someone else’s experience if you can.

With the cams all set and the bike back in one piece, I gave the bike another comp test and then headed off to the dyno. I do a second comp test more out of interest than anything else. The cranking comp had risen with the cam dial from140/150 to 175/180. Pretty normal really.

Dynobike had just got the new lamdba probe setup running, so this was to be my first time with this available. I went ahead and did a base run, then looked at the lambda trace and thought "well, lets try to get this right". So, instead of following my usual and proven approach, I was dazzled by the new tech and wasted an hour or so getting nowhere. This is not to say the info provided was not good. It was just the way I was approaching it. As always, you have to know how to use the tool before you can create any good with it.

At this point, I went back to my normal procedure and 5 minutes later had the info I needed. Steve just laughed at me, pointing out that it wouldn’t be the last time it happened to someone. I did make one mistake though. When I decided to go back to my normal method, I was so annoyed that I removed the lambda probe from the exhaust. Later I realised it would have been good to see the traces, even if I wasn’t going to use the info directly. Below is the graph I end up with after my first trip to the dyno with a bike. Usually, I will settle on the required mods to the fuel map while there and do a final run. This wasn’t to be so easy, however, as this bike runs an old P7 ECU. We had to fit an Additional Memory Board from FIM so we could make and store changes to the fuel map. I hadn’t used one for quite some time, however, and it works very differently to the later zone chips, so I took the info home so I could plot it all on the laptop and work out my mapping changes.

This graph shows the best of the various runs. I make an overall change to the map and do as many runs as is required to get a consistent result. Given you can make a change of +/- value to the fuel map via the hand held terminal with the engine running, this is quite a quick process once the initial consistency has been reached. Often it takes 5 or so runs to get 2 consecutive runs that are the same when you first start testing. Then you just go through as many levels of +/- as you need. On this graph I went from +30 ( red ) to –10 ( yellow ), so you can see how much we often vary the maps. Using the torque curves makes the lower speed variations between each a lot more obvious than the power curves also.


Dynograph courtesy of DYNOBIKE (03) 9553 0018

After an hour in front of the laptop at home that night I had all my changes planned. Ten minutes the next morning saw then in the ECU, and I was ready to go. Well, ready to go to try to sort out any other problems it had off the WOT line. The final dyno graph is shown below in red, against the original in green. The torque curve is shown below that.


Dynograph courtesy of DYNOBIKE (03) 9553 0018


Dynograph courtesy of DYNOBIKE (03) 9553 0018

A very obvious improvement, in contrast to the minor improvement in dyno terms I got from the 851 SP3 I have previously done. This final graph is much closer to the final graph of the SP3, with the same profile in general. Just missing a lump at 7,000 RPM, as seen below


Dynograph courtesy of DYNOBIKE (03) 9553 0018

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