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

















At the moment the spark jumps the Gap it causes a high frequency burst of energy, known as RFI (radio frequency interference). RFI, as its name suggests, creates static on your radio and interference with other electronic equipment, including the vehicle’s on-board electronic control units (ECUs).


Resistor plugs were developed in the 1960s to suppress some of the spark energy, thus lowering RFI to an acceptable level.  Most Resistorspark plugs use a monolithic Resistor, generally made of graphite and
glass materials, to filter the electrical voltage as it passes through theCenter Electrode.


Since Resistor type plugs actually “resist” some of the spark energy, non-Resistor type plugs actually deliver a more powerful spark.  It is for this reason that most racing plugs are non-Resistor types.  However, in most automotive applications, a Resistor plug is required for proper vehicle operation.  Use of non-Resistor plugs in
vehicles that call for a Resistor type can result in rough idling, high-rpm misfire, and abnormal combustion.


Well, I have been disassembling my M1Rs for a few days now. I have most everything apart and in well-marked bags. After asking around on the Pantaheads list, my attempt to source new screws and bolts came to a (well-deserved) screeching halt. I had a lot to learn about the strengths of certain alloys, the proper type of metal and coating to use for each location, and the ugly reality faced when finding the perfect screw and learning you can only buy 100 and not just the 1 you need.

So, as of now… I am reading. I have a lot of reading to do.






This is a partial list of hardware that I replaced on my Marzocchi M1R forks. Eventually, I will organize this to include both low-cost and fancier metal and coating options. Izaac (from Pantaheads) just turned me on to yellow zinc screws. Now I have to start my list over.


  1. Eagle Day
  2. McMaster Carr
  3. Fastenal


Rebound adjuster:

  1. #8-15 x 5/8″ Phillips Flat Head Sheet Metal Screw [A4 316 SS]  x 1
  2. Black-Finish Steel Internal Retaining Ring for 17mm Bore Diameter x 1
  3. Metric Spring Steel Shim – DIN 988 0.1mm Thick, 10mm ID, 16mm OD x 1
  4. Metric Buna-N O-Ring 1.5 mm Width, 11 mm ID x 1
  5. Metric Buna-N O-Ring 1.5 mm Width, 5.5 mm ID x 1
  6. M6-1.0 x 20mm Socket Head Cap Screw [A4 316 SS] x 2



Bottom of forks:


Cross brace:


These are the markings on the stock seals from my Marzocchi M1R forks.

(in order of assembly)

Dust seal: Marzocchi 41.7 Rolf 4

Metal washer

Stop ring

Oil seal: Marzocchi 3 41.7 55 10 10.5 RP Rolf


In celebration of being back online and on my new server, I thought I would take a pass at making a new logo for the site. I tried to tie in the new Corsa shield design with all of the old Guigaro-designed logo from the 80’s. Enjoy!

My new Ducati Pantah logo