Wednesday, October 31, 2012

Rewiring the pickups

This is not about mouse-gnawed wiring harness for your old Chevy pickup, although the effects are the same. Inside a lot of Ducatis the wires from the ignition pickups get hot and brittle. Actually it's more likely the insulation around the wiring goes bad. Which is what will happen when they sit in hot oil all of their lives. So some 30 or so years later there are problems.


You can see here there was an attempt to shield the stock wires with the orange covers. But even that effort can only go so far.

One of the preferred solutions is to replace the wire. Nowadays even mere mortals have easy access to what was once space-age parts, thank you Internet... Military grade wire is now available at the click of a button and not at an unreasonable cost.

Depending on where you are in the world you may even find a local supplier. The recommendation is a gas and oil resistant AND heat resistant PTFE insulated wire.  The milspec to look for is MIL-W-16878 although you may find similar wire without that spec. On top of that you may want to consider a PFTE heat shrink too.

When I get around to it I'll document the actual process but for now here's one person's instructions:


Method;--  Snip ONE lead, about 1" to 1-1/2" from the coil. Test at the plug to see which lead is still connected with continuity meter, bearing in mind the coil resistance is about 220 ohms. (mine measured 216 ohms.) So, you now know which lead is which. Snip the second lead to the same length. Carefully scrape any remaining insulation, and scrape the surface to reveal the copper wire. clean as required with solvent (carb cleaner?), and continue to gently scrape until you can see enough copper to be certain of a good surface for soldering. Twist your new wire onto the tail, and quickly solder the joint without allowing too much heat into the coil. (HOT iron and speed!)
Repeat for second wire, and then for the second pickup.
Thread a thin HS cover onto each wire, and shrink. Thread the next size larger HS onto the one pair of wires and shrink. Repeat for second pickup. At each stage, seal the end of the HS with a decent silicone sealant. I use a Loctite one, I forget the number right now, 5920 perhaps, a low odour (no acetic acid smell), oil resistant and high temperature resistant with a copper colour.
You now have two twin leads, work out how they will lie, so that they will not foul anything, then slip on the next size up HS sleeve, fasten in place with the metal clips, thread out of the cases, seal the exit point with more loctite, cut to length and refit your connector. In fact I used bullet and socket connectors and replaced the original connector.
Fire up and ride away!
Les.
In addition some people are also "potting" the new wires to the pickups. I'm not sure what potting material they are using.


 From http://www.mdinaitalia.co.uk

From http://beltandbevel.com.au/

The photos may not be Alazzurra specific as many Ducatis with ignition pickups may need some help.

More later.

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