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1 month 4 weeks ago #4613 by 8166
There are also several electrical system maintenance tasks that should be done on any new-to-you airhead. The Engine Control Unit (ECU) is mounted on an aluminum heat sink, and the heat conductive paste between the two can dry out and allow the ECU to overheat. Remove the fasteners holding the two together (sometimes rivets must be drilled out), clean the surfaces, and apply a generous coat of heat sink paste to both surfaces before reassembling. Do not use dielectric grease or any other grease or paste you have on hand. If you can't find it locally, go online and get the real stuff.

Corrosion is the enemy of electrical connections, and that's especially true for motorcycles that spend time in the rain. Even the newest airhead has connectors that are almost a quarter century old, and I can guarantee you you'll find some surprisingly dirty stuff if you go looking for it. And you should go looking for it before it causes you a problem. Search along the wiring harness for various plugs and connectors, pull each one apart, and clean the contact surfaces using a pencil eraser, fine abrasive sheet, or needle files. You can also find tweezer like diamond files made specifically for this purpose that make the job very easy, especially for the round type terminals. On reassembly, I use a product called DeOxIt to further break down any remaining metal oxide and prevent new oxides from forming. DeOxIt is especially good at reviving the contacts in handlebar switches without having to disassemble the switch. It can take a while to work, perhaps even overnight, but DeOxIt is the first thing I'll try for fixing a balky switch.

When you're done with the wiring harness, remove and clean the contacts on each of the bulbs and sockets on the bike. The lead used on bulbs is especially good at corroding.

Then take a good look at the battery terminals, and the heavy wire leading up to the starter. You'll have to remove the starter cover to get at that one, so don't forget to disconnect the battery ground lead at the battery to prevent inadvertant sparking. Do the same when you remove the front engine cover to get at the wires on the alternator and auto advance unit.

While you've got the engine out, you should also clean and lubricate the splines between the transmission input shaft and clutch disc. The grease used to do this is something of a sacred cow in airheadom, and for many years Honda 60 moly paste was the go to recommendation. Unfortunately, Honda has discontinued the 60 paste, but the Honda replacement is rumored to be just as good.

If you're seeing oil leaks on the bottom of the engine, very likely the pushrod tube seals have hardened or even split. Replacing them requires removal of the heads and cylinders, a job that sounds big and complex but that is not. Oak's Top End Manual is still available through the Chicago BMW Club, and I recommend it as a guide in performing this work.

Very rarely the oil pan gasket will leak, and sometimes a stripped thread on one or more of the bolts will be the cause. A helicoil repair is the cure, but be aware that some of the holes go all the way through, so grease the drill bit and tap to keep chips out of the engine on those through hole repairs. And a smear of good silicon based gasket sealant on the threads of the bolts that go into through holes will keep them from leaking, but do not use any sealant on the BMW gasket. It already has a heat activated sealant on it. In fact, do not use gasket cement on any gasket on your airhead.

But do use just the thinnest smear of sealant on the cylinder bases, which on your RT do not use gaskets. Over doing the sealant can block the tiny and somewhat hidden oil passages at the top of the two top cylinder studs where they emerge from the engine block. I like to use ThreeBond 1207B (black), and spread it out so that it leaves a thin gray film on the engine case and cylinder base.

8166 Scot Marburger, This email address is being protected from spambots. You need JavaScript enabled to view it.
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1 month 4 weeks ago - 1 month 4 weeks ago #4614 by Wobbly

8166 wrote: The Engine Control Unit (ECU) is mounted on an aluminum heat sink, and the heat conductive paste between the two can dry out and allow the ECU to overheat. Remove the fasteners holding the two together (sometimes rivets must be drilled out), clean the surfaces, and apply a generous coat of heat sink paste to both surfaces before reassembling. Do not use dielectric grease or any other grease or paste you have on hand. If you can't find it locally, go online and get the real stuff.


Fully agree with this point.

Having retired from the Military electronics industry, and knowing that my company tested lots of heat sink pastes before standardizing on one in particular, I will share the product's name... Arctic Silver.

Link to Arctic Silver on Amazon

The object is not to be overly generous. The object is complete surface coverage. You want to achieve the thinnest coat that fully covers and joins the two surfaces without air bubbles or voids. A central puddle that is spread with the edge of a credit card (yours, not mine :P ) usually does the trick. Then, the application of correct fastener torque to insure the surfaces to not end up bowed or warped.

Hope this helps.

Don't hide 'em, Ride 'em !!
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Last edit: 1 month 4 weeks ago by Wobbly.

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