I have today received a replacement regulator for my 91 900ss. Electrex list part number RR51 as the one for a shed load of Ducs of various models. Now my worry is that the two yellow feed cables from my altenator are twice the size of those it links to on the new regulator.
Does this sound right to you ?
Have you the same unit and are the yellows small the same as mine ?
Has anyone had problems with Electrex replacement units or what part numbers have you fitted ?
How strange, I've just fitted the same thing and am yet to fire her up!
I was a bit more concerned about the connectors after reading tales of woe on other sites. I've decided to solder the connections and get rid of the yellow connectors altogether.
I really wanted to resite it totally but its so much hassle and I have too many other pressing things to do.
Frank did you notice the sizes of the yellow wires ? All the tales of woe seem to be based around the feed coming from them, so why are they so small on the replacement item? I am going to make a call in a minute. K
I bought the exact same item, and the wires were a little on the small size However was informed that these regulator are better at dispercing the heat, and as a result are more reliable, However I still cut the wires back to about an inch and a half and used larger guage wire.
There are two concerns here. The I-squared-R heat transferred to the insulation from the 30 amps being carried by the wire and the external thermal environment that the insulation sees. Any in-line connector will be the point of highest in-line resistance, especially if the connectors become corroded as they are prone to be. That's why the insulation gets crispy adjacent to the connector and why it's a good idea to solder the wires together.
The wires that are connected to the stator see a quite hot environment since they are run in a common sheath near the engine. This common sheath is a major factor in regulator failures because it holds the wires together along it's length, and as the wire's insulation property degrades, the wires short together intermittently and cause damage to the regulator. The sheath is probably there for abrasion resistance to provide additional insulation to adjacent engine and chassis parts. I took it off.
The first evidence is usually burnt insulation adjacent to the connector to the regulator and most people just cut out and replace this section of wire. But if you check the wires inside the sheath you'll find that the insulation there has also been damaged and should be replaced as well. The insulation on my 916 in the sheath was so soft that I could cut it with my fingernail. I had to replace several regulators until I found this root cause.
The answer to your question about wire sizes is that the size required is larger in hot environments to avoid insulation degradation. The insulation material and thickness selected is also a function of the service environment as well as voltage and current carried.
Well the man from Electrex said that the wires are correct for the job. Cant say he was to helpfull though. Sort of made me feel I was asking a stupid question. SO THE QUESTION STILL REMAINS Why the difference in cable size, Why should Ducati feel the need to put such a big wire on and Electrex dont.