Twin-cylinder four-stroke air-cooled rebirth of a Ducati 500SL

After unpacking the engine from the shipping crate, I started by degreasing some of the main parts that I could separate. I took off the engine covers by using allen sockets and a 3/8″ socket wrench. The cylinder heads were already separated and in a different box. The clutch was already dismantled. In fact, I don’t think many of the parts that came with my engine as a whole were actually part of the same engine. No matter. They are all from a 650 and I am not doing a “historically accurate” restoration.

I used a citrus degreaser and a plastic scrub brush that I found in a hardware store near the paint stripping section. It has nice short stiff bristles, but won’t scratch the aluminum. I used a whole can of degreaser on just these 4 parts, so I would suggest 3 cans if you plan on doing the whole engine.


Clean the parts away from where you will be working. That run-off never really goes away. It smells nice, but it is real messy and thin melting grease seems to get everywhere. You can see pics of my top-notch restoration clean-room under the porch here at my house:



It would be great if someone could fill in the gap on how to start degreasing and prepping your engine when you remove it from the bike. Mine was already partly-disassembled so I am missing some steps. Please e-mail me if you remember to take some pics before starting! Thanks.

Remove the cylinder heads

The next step would be to remove the cylinder heads by loosening the head nuts with an open-ended wrench. As my heads were already removed, I hope someone can help fill this in for me. [INSERT HOW-TO REMOVE HEADS]

Remove the cylinder liners

After removing the heads, the cylinder liners should be removed. These can sometimes be assisted by tapping them with a dead blow hammer. If the hammer has two striking surfaces, use the soft plastic or rubber side when striking the cylinder liner to prevent damage. Be careful when removing the cylinder sleeve from the piston as not to damage the surface of the piston by dropping it on the sharp edge of the engine block after the liner is removed. My liners came out quite easily. Let me know if you have trouble removing yours and if you have other suggestions for removal.


Twin-cylinder, 90° L-type configuration, 4-stroke, air-cooled, mounted on closed double cradle frame.

Bore 82mm
Stroke 61.5mm
Capacity 649.5cc
Compression ratio 10:1
Max power 56.5HP @ 8400 rpm
Max torque 40.5 lb. ft. @ 5750 rpm
Max engine speed 8900 rpm

Valve Timing

-612549 +612550
Induction before TDC 40° 39°
after BDC 70° 80°
Exhaust before BDC 67° 80°
after TDC 43° 38°

Operation and clearance of tappets, cold motor condition:

Intake and exhaust opening rocker arm 0.10mm (0.0039″)
closing rocker arm 0.00%0.02mm (0.00%0.0008″)