Work Shop Manual

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DUCATI 4 and 5 Speed Single Overhead Camshaft Motorcycles WORKSHOP MANUAL

Disassembly, Cleaning, & Preparation

Completely disassemble engine. Place a tie wrap at each end of all shafts to retain correct shim placement. Bag each sub assembly separately and use lots of boxes. De-grease and wash disassembled parts.

The rear engine mounting holes should be drilled and then reamed to .375 in. to prevent the engine from "working" in the frame. Assemble the right and left cases, located on the dowels, and secure them together with several M6 cap screws. A milling machine should be used to drill square through the cases and the dowel that is located in the bottom hole.

Install HeliCoil inserts in any damaged M6 threads in aluminum castings.

Sand out any scratches on the exterior of the cases with emery paper. Use old M6 bolts to prevent beads from entering blind threaded holes then bead blast to clean parts with clean, medium size, glass beads. Wash all parts in soap and water before assembly. Be sure to clear oil passage ways.

Cylinder Head

It's best to start with a small valve (Monza) head because of the additional material available to shape the ports. Before you remove the old valve guides machine the valve seats to 1 mm under size then heat the head to 325 F and press out the old valve guides. This way you can do all of the porting work without worrying about damaging finished valve seats.

Start by removing all new material exposed by enlarging the valve seats, blend the area behind the seats as before. The exhaust side is now ready for final valve cutting. On the intake side, try not to remove any material from the floor to maintain as much of a drop to the seat as possible. It's possible to build up the floor of the port using epoxy. Remove material from the top of the port, working on both sides of the valve guide to create a vane shape leading up to the guide bore. You must leave enough material around the guide to support the loads applied to it by the valve operation. Use outside calipers to check the thickness of the roof of the port. The intake diameter at the flange should be 32mm (intake valve diameter multiplied by 0.8) for a 34mm carburator.

Install new valve guides and finish the valve seats. Use Mach 1 valves: 40mm intake and 36mm exhaust. Replace the stock valve springs with a R/D coil spring conversion kit. Be very careful to set the installed height of the springs. With the over the guide type of lower spring retainer you may have to mill the mating surface on the head. You must also grind away the head to allow clearance for the coil springs.

Use late model two valve desmo opening shims. Tappet clearance is .005 inch for intake and .007 inch exhaust. Rocker arms must have the hard resurfacing replaced and reground for the hotter cam. You can have this done at Syds or Megacycle.

Install a HeliCoil insert in the spark plug hole to save problems latter.

Cam Shaft Specs & Valve Timing

Megacycle cam shaft number 564-00 www.megacyclecams.com.

Be sure to degree your cam shaft when you install it and you must have the engine on the bench to do this. Use light wieght springs and setup a dial indicator on both valves. You can make up steel plate for the magnetic base and attach it to the side of the head with M6 screws.

Piston Squish Clearance

Set piston squish clearance at .028 to .030". Measure clearance using a circular loop of .030" diameter solder wire. Adjust squish clearance by varying the thickness of the base gasket.

Ignition

Dyna DC3-1 Green 3 Ohm Coil. Mount the coil on the frame down tube so that it is in the air stream. You can use the stock points and condenser with fixed advance or Dyna S electronic pick up. Set the advance to 38 degrees before TDC.

The Spark Plug is NGK B7HS, B8HS, or B9HS. Use copper core wire for the spark plug leads.

Remove the stator completely and use a total loss ignition system. Replace the plastic fitting where the alternator wire exits the engine cases with the same fitting and aluminum gasket used at the engine oil filler.

Kick Starter

Remove the kick starter assembly completely. Use a lathe to turn an aluminum plug that is installed from the outside of the engine side cover with an O ring gasket and secure inside the side cover with a larger washer and M6 cap screw.

Lubrication

Use 2 Litres of 40 wt motor oil available from Kendall or Castrol. Replace the oil every time you ride the bike.