This is Georges 900 SL, the brief for this Ducati was to build the ligtest 900SL possible that is also a competative and practicale racer. The 'doner' bike was a 900SL that would be stripped to the absolute last nut and bolt and rebuilt around Piorobons Alloy F042 frame kit.
Pierobons F042 kit is a complete chassis kit intended to be built using stock Ducati parts allowing a complete lightweight Ducati race machine to be within the grasp of the club racer and enthusiast. The kit is based around the use of the 1000DS engine and chassis parts from the 1000SS IE. Our own F042 will used Ohlins road and track forks, wide track yokes, the 900SL engine with a 980 Big Bore, flat-slide carbs, Dymag wheels and copious amounts of Ti and subtle special parts.
The first steps of this build was to strip the engine and have the cases (above) badblasted to remove the years of grime and flakey paint. The freshly cleaned cases were then sent for machining of an additional oil gallery, the cylinder mouths opening out to take the larger barrels and the filter pocket machined out. (below)
To lose as much weight as possible and allow the engine to 'spin up' faster, as much recipricating mass as possible was lost, this would allow the counterbalancing webs to be removed from the crankshaft.
The 'weight loss' here was acheived with the use of Ducati 999 F06 connecting rods. These are the rods as used by the 'Airwaves' 999 Ducati's. The rods are re-sized for correct centres to suit the 900 engine, work carried out by 'Couger Red' using materials unique to formular one racing engines!!
The big-bore 890 pistons are also lighter than the stock items even though they are a bigger piston. The crank was re balanced and 'knife edged' to suit the modifications.
All new bearings are fitted to the cases and the crank, gearbox and F06 selector are shimmed in to correct clearances.
Gear ratio's were chosen that would maximise the flat power curve from the mid-range torque developed from a two valve engine with it's limited top-end rev limit (compared to the peaky powered RS close ratio box) The original gearbox shafts were changed to allow correct chain alignment and allow quick and easy sprocket changes.
Here is shown some of the lightened parts opposite standard items used for this engine build, they include lightened primary gears, starter gears, timing gears and starter sprag support. The flywheel is replaced with an aluminium item which alone loses over 1kg. Ti bolts and careful machining would all add to weight savings.
The engine (above) is shown in its 'dry build' stage and currently weighs 6kg lighter than the stock engine in the same build position. As an indication of saving, the 749 crank in the drain tray weighs 4.5kg!!
The engine goes through it's final assembly after setting the squish and dialling in the cams, the heads have been flowed and prepared by MBP in the USA, the cases were modified by 'Kahmna' in Germany to suit their 890 big-bore kit and the Mikuni flat slides also imported fom the United States.
The frame and engine finally come together along with the Ohlins forks, radial Brembo master cylinders, Ohlins rear shock and modified swing arm.
The bike requires a lot of bespoke brackets and hangers, so a template is made for each bracket as required and then they are fashioned from the appropriate materials - usually alloy. The picture also shows the exhaust is now fitted along with 16.5 inch wheels. The change in wheel size led to the rear swing arm being returned to Pierobon for further modifications for spindle size, hub width etc.
If you have any queries or questions, require a quote or just need a little advise then please feel free to mail me at firstname.lastname@example.org or give me a call on 01858 535 411 or 0784 1099 998.