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

Markings indicate ZEM type 3504 64.
ducati_650_flywheel_01

ducati_650_flywheel_02

ducati_650_flywheel_03

ducati_650_flywheel_04

ducati_650_flywheel_05

ducati_650_flywheel_06

ducati_650_flywheel_07

Unscrew the fixing screws and pull out the starter motor. My Ducati Alazzurra 650 starter type is SU022.

ducati_650_starter01

ducati_650_starter02

ducati_650_starter03

ducati_650_conrod_08

When you remove the connecting rods, be sure to mark the top and bottom halves with permanent marker. This way, when you reassemble them you can guarantee that they will be correctly balanced. Don’t forget to mark which one is attached to the vertical cylinder and which one is attached to the horizontal cylinder. On the Ziploc bag, draw the arrangement of the connecting rods in relation to a marking on the crankshaft as well. When you go to put them back in a few days-weeks-months-years it will help ease the fear that you are not reassembling them correctly.

piston_new

Markings on top of standard pistons pulled from a 1986(?) Ducati (Cagiva) 650 Alazzurra engine have the following markings:

  • 82-67677A => (arrow) on the top
  • “A” logo on the inside
  • Made of aluminum
  • 3 rings (2 sharp metal, 1 with a spring in it)

ducati_650_piston_06

ducati_650_piston_041

ducati_650_piston_03

ducati_650_piston_05

ducati_650_piston_01

cutaway_sparkplug

The stock plugs in the Alazzurra 650 engine were NGK BP7HS spark plugs.

I replaced the stock plugs with Denso Iridium IWF22 plugs. I had these in my 1974 Land Rover, and have them in my Jaguar XJR as well. I really started using them in the Land Rover and they were the only plugs that ever really ran smoothly in my 2.25L. I haven’t done any other experimentation in my Pantah, and I am sure cheaper plugs will work equally well. Let me know if you have had success or failure stories.
Or visit the Official Denso Iridium page.

Other spark plugs that will fit the Alazzurra 650 engine: (these links go to sparkplugs.com … no affiliation)

  1. Autolite options
  2. Champion Options
  3. Denso Options
  4. NGK Options
  5. Splitfire Options

Begin by removing the spark plugs from the vertical and horizontal cylinders. This is a straightforward procedure unless the plug is corroded in the head.

Ducati provides a spark plug removal tool in the tool kit that comes with each bike. This is a pipe-like tool with a hex formed at one end and a hole through which the handle is placed. It fits, it works, but it isn’t the best choice if you have access to a shop.

I use this socket set from Sears and a short 3/8″ extension on a socket wrench to remove plugs. The spark plug sockets have a rubber insert that holds the plug in place when you remove it. It works equally well when inserting plugs. The main benefits are that you don’t drop the plug and knock dirt and grime into the plug holes and it also prevents changing the plug gap if you drop the plug while inserting it. Both of these things fall into the “I probably won’t fix it” category.

Using the right tools for removing a spark plug may not seem like a big deal. The second you snap off the head of a plug or crossthread the head, you’ll make sure you have the proper tools. I have done both over the years. I am always wary of using a socket extension that is too long. Whether you are loosening or tightening the plug, a 12″ or so extension tends to angle itself on the plug and can result in a snapped plug.

If you are not planning on rebuilding the engine, make sure to plug the holes with a cork or rubber stoppers to prevent dirt from entering. Grime tends to collect aroud the plug holes and removing the plugs usually knocks nasty stuff down there.

Be sure to check out my page on sourcing replacement spark plugs here.