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Ducati Capacities

Latest revision: Oct ’04.  749R - 96 x 54, plus more about swapping bits between models added.  I’ve been learning.

A table of various capacities for Ducati models, plus all the possible combinations thereof.  Some are “race” from the 4V series, some are “big bore kit” for the 2Vand 4V.  The odd bores – 90.5, 91 and 95mm - seem to be becoming popular, mainly due to practical overbore limits of std cylinders and the 800 cc limit in some twins racing classes (based on 748). 

• Std Capacities, Small 2V: 349 (350), 398 (400), 499 (500), 583 (600), 618 (620), 650, 748 (750), 803 (800)
• Std Capacities, Large 2V: 904 (900/906/907), 944 (ST2), 992 (1000/ST3)
• Std Capacities, DESMOQUATTRO: 748 (IN RED), 851, 888, 916, 996
• Std Capacities, TESTASTRETTA: 748 (749), 749 (749R), 997 (996R/998/999), 999 (998R/999R)
• DESMOQUATTRO Race Only Capacities: 926, 955
• Ducati Performance 2V Big Bore Kits: 674 (680), 782 (780), 944 (IN BOLD BLUE)
• Ducati Performance 4V Big Bore Kits: 854 (853), 955 (IN PURPLE)

Some notes for component swapping – not an absolute list by any means.

• The cylinder stud spacing variations are: ‘Small blocks’ (small 2v), ‘Large blocks’ (900/906/907, ST2 and 748/851/888/916), ‘996’ (996, ST4S, S4R), ‘Testastretta 100mm bore (998/999/1000ds/ST3)’ and ‘Testastretta 104mm bore’.  Swapping cylinders between these is not possible. Well, not easily.  The holes in the cases for the cylinder spigots to go into can also vary.
• On ’02 models (maybe ’01 sometime) the locating dowels for the cylinders were moved from the side or front to about 45 degrees off front.  So base gaskets differ for anything in this build range.  Very annoying.
• The ‘Small 2V’ cranks have smaller 40mm big end journals than the other engines at 42mm.  The rods are the same length as the 4V rods, but I would expect not as strong.  The small ends are also smaller – 18mm as opposed to 19 or 20mm.
• The ‘Large 2V’ rods are longer than all the others – about 5mm, and have the same 42mm big end as the 4V.  They have the 19mm small end though.
• The 4V rods vary between manufacturer, material, small end size (916SP is 21mm, all others 20mm I think) and method of location.  The 996 models (and maybe ti rodded 749SPS/R) have the rods located for side movement by the small end in the piston, whereas all the others are conventional big end located.
• Cranks vary with alternator width (up to ’92 and ’92 – ‘98) and type (’99 on).  As far as I can tell, any ’99 on crank will fit any of the bottom ends similarly. 
• The 851 and 900 cranks got wider in ’92 – with the’92 year model for the 851 and at 900SS/SL engine number 007089.  The 900SS/SL parts listing says up to engine number 006908 were narrow and from 007089 were wider.  I have no idea what happened from 6908 to 7089.  The alternator covers vary in width accordingly.  With a wide cover on a narrow crank the end of the crank misses the crank end bearing by about 6mm.  Fairly obvious.
• The pre ‘92 64 and 68mm cranks will go into the small engines and have the same 6 spline flywheel mount.  Although you will have to machine the timing shaft to clear the rods.
• The ’92 on cranks are 18mm longer at the alternator end and have 12 spline flywheel mountings. They also have larger timing gear mount diameters.  Same engine numbers as above for these changes.
• The corresponding narrow alternator for the narrow crank is listed as fitting all 600 and 750 up to and including ’97, 900 to engine number 007088, 851 up to and including ’91 and 888SP5.
• The 70mm stroke comes from a ’90 – ’92 narrow 68mm 900 crank offset ground to 40mm big end to go into a “small” engine.  Yes, I have a spare one hanging around.
• The timing shaft bearing in the LH case varies between P7/P8 and 16M ECU engines.  900SS carb models have the P7/P8 size which is larger.  An ST2 shaft doesn’t work in ’97 900SS cases.
• The 6 speed gearbox from the larger engines won’t fit the small 2v engines, due to the shafts being slightly further apart.  The new 6 speed gearbox from the 800SS/M engines will fit, and is much the same as the 6 speed gearbox from the 400 engine I am told.  Ducati Performance is also offering this gearbox kit as a part for the small 2v engines.
• If you could fit a 1000SS/M crank into a 998/999R you would get 1215cc.  Cool!  Might need some custom Carillos for that.

Of course, don’t take this as totally correct.  Do your own measurements before you purchase anything, but they are all the same engine pretty much.  Just a glorified Pantah, even the Testastretta.

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