Ducati 900 SSie WITH HI COMP PISTONS

Something I have wanted to try for a while, this was the next step for an owner who had already gone the dialed cams route. I didn’t get to dyno the bike before I started as I ran out of time after the previous work was done, and it arrived crashed after a track day spill for the next stage. The owner had been looking at trading up to a 996, but decided the 900 SS fitted him much better. He just wanted some more go.

At this stage I had to make it clear to him what he was playing with here. Given we were starting at around 85 hp, I didn’t think there was that much more left in the engine. Realistically, 90 hp was about all I could see coming. Our man was quite happy with that, so off we went.

The mods were as follows :

• high compression pistons, machined to give 10.8 : 1
• cleaned up cylinder heads, with minor port work
• 44mm inlet valves, up from 43mm standard
• Ducati Performance light weight flywheel

The larger valves were fitted not for the sake of a larger valve, but to allow the port shape from the bowl thru the throat up to the seat to be made much nicer. The port was much cleaner up under the valve, and blended well with a nice three angle job on the seat. The port work itself was really just a good clean, as I couldn’t see the point getting carried away. Cost was also a consideration – I couldn’t justify spending too much of someone else’s money here. The high comp pistons came with a bit too much comp for this application, so we machined the tops down a little to give a good road bike figure. The piston weight was also very close to the std piston weight, as the new ie engine pistons are around 50g lighter than the old carb ones. The lightweight flywheel went in like usual, and off we went to play with the setup.

The fueling didn’t need changing too much at all, and the result was about as nice as I could have hoped. Smooth and very responsive, with a nice charge all the way through to the top end. I had a feeling there might be some more low and mid range to be had in ignition timing, but this wasn’t to be.

Anyway, the dyno curve. Red is this bike in its current setup. Unfortunately I don’t have any other runs for this bike. The remaining runs are for the bike used in the previous cams dialed, open airbox report. Blue is cams dialed, green is slip on mufflers only and purple is std. According to the owner, the real benefit of this work comes out in third and higher gears, as the engine pulls toward the red line. While the bike now lifts in second with ease, the acceleration from speed is very impressive, letting him keep up with his riding mate’s 916 SP.

This second graph shows the torque curve for this bike compared to the curves for two different standard bikes. The variation in the std bikes is a little surprising. The blue curve is for the bike used in the cams dialed report, which may have been a bit on the low side std. Or perhaps the other bike ( green ) was particularly good. In either case, the increase in the torque output makes it obvious why this bike feels so good.

Now the reality check. This was not a cheap job, with the total cost coming in at around $3,000. Whether or not this is for you is a decision only the owner can make. Changing bikes for one more suited is often a better decision for many people. But, as in this case, if the bike you have is what you want, the money spent makes it even better.

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