Ducati Capacities

Revision Jan ’10.  Later models, etc.
Revision: Oct ’08.  I was wrong about early 851 cranks being narrow, amongst other stuff.
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 2V and 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, 696 (695, 696), 748 (750), 803 (796, 800)                                                                                                                             
• Std Capacities, Large 2V: 904 (900/906/907), 944 (ST2), 992 (1000/ST3), 1079 (1100)
• Std Capacities, DESMOQUATTRO: 748 (IN RED), 851, 888, 916, 996             
• Std Capacities, TESTASTRETTA: 748 (749), 749 (749R), 849 (848), 997 (996R/998/999), 999 (998R/999R), 1099 (1098), 1198                                                                                                                                      
• DESMOQUATTRO Race Only Capacities: 926 (888), 955 (916)
• Ducati Performance 2V Big Bore Kits: 674 (680), 782 (780), 944 (IN BOLD BLUE)
• Ducati Performance Desmoquattro 4V Big Bore Kits: 854 (853), 955 (IN PURPLE)
• 95mm piston and cylinder kits for 851 sometimes come up on Ebay – they give 907cc                                 

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, 998/999/1000ds/ST3)’ and ‘Large Testastretta’ (104mm bore 998R/999R, 1098, 1198).  Swapping cylinders between the different variations is not possible. Well, not easily.  The holes in the cases for the cylinder spigots to go into also vary.
• On ’02 models (maybe ’01 sometime) the locating dowels for the cylinders were moved from the side 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 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 6mm (130mm versus 124 I think), 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, all production Titanium rods and Testastretta models have the rods located for side movement by the small end in the piston, whereas all the others are conventional big end located.
• 749R has longer rods than any other 749 engine, and run the same piston compression height as the 999.  So the 749R rods must be 4.25mm or so longer
• Cranks vary with alternator width (900SS up to ’92 and ’92 – ‘98) and type (’99 on). 
• The up to 99 models ran the single phase alternator with the magnet rotor spinning inside the stator.  These alternators have 2 yellows wires going to the regulator.
• The single phase alternator has two different width rotors.  The narrower rotor was fitted to the small blocks (600, 750), 900SS/SL up to engine number 006908, early 851, 851SP, 888SP and the ’97 ST2.
• The ’99 on 3 phase alternator has the magnets in a large dish style arrangement that spins around the stator.  These have 3 yellow wires running to the regulator.
• As far as I can tell, any ’99 on crank will fit any of the bottom ends similarly. 
• The 900SS/SL cranks got wider in ’92, from 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 900SS/SL 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 900SS/SL 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 900SS/SL cranks are 18mm longer at the alternator end and have 15 spline flywheel mountings. They also have larger timing gear mount diameters.  Same engine numbers as above for these changes.
• All other large block single phase alternator cranks are the same width – 906, 907, 851 ’89 on, 888, 748, 916, 900M, ’97 ST2.
• The 906, 907 and ’89 – ’91 851 cranks have the 6 spline flywheel mount.  Although the 851 SP2 and SP3 have the 15 spline I believe.
• The ’92 onwards engines had the 15 spline flywheel mount and are larger where the timing gear sits by about 5mm from memory.
• The lighter cranks were lightened by machining in two different ways.  Early SP cranks had a groove machined out of the inside of the web around the full width, whereas 916SPS onward cranks have the ears cut off the webs.  The 749R cranks were the first to have hollow big ends, with drilled oil passages instead of the large oil gallery with the screw in plug.  This was then used on the 1000ds crank and most other new cranks afaik.  A std crank is about 4.5kg, a light crank about 4kg.
• 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.

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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