imported post
Dupe, the longer answer is that it could be any one, or combination of, a number of problems that are causing your 1200 to die. Depressing, eh? (I'm Canadian. Couldn't resist the EH

) No fun sitting on the side of the road. Been there. Done that. Hope not to again. Back to your problem. It could be any of these, and possibly others;
1. Bad fuel. I had my '87 leave me on the side of the road in Montana in June and the dealer I talked to in Missoula told me the horror stories their shop is having with the poor quality of gas in that area. Said it's so bad that the weekend ATV warriors are experiencing gummed up systems from lack of daily use of their ATVs. His wife had taken a small jar of Regular (87%) gas, with 10% ethanol, and placed it in a sunny window for 3 days and it developed a green scum on it. Ethanol is a bio-organic substance made from corn. It'll grow under the right conditions. Imagine that in your bike's system. Good argument for running no-ethanol fuel.
2. Fuel filter. Lots of literature on this site about the things that will clog fuel filters and refuse to let the bike run the way it should. Condition of the fuel tank may play a role here. Also, see #1 above.
3. Gas cap problem causing vacuum and reducing the ability of the fuel pump to deliver fuel. Solutions range from soaking the gas cap in Seafoam to drilling holes in gas caps. Again, lots of info through the index and search engine on this site.
4. Pulse generators (pulse coils) giving up the ghost. This is a not too uncommon problem with 1200s. The pulse generators send signals to the coils to do their thing and to the fuel pump to go ahead and pump that fuel. There is, again, a lot of literature on this site as to how to check them before replacing them. Not too difficult or expensive to replace. This turned out to be my '87s problem. Replaced it and it never again left me on the side of the road putting the Harley cover over the bike:cooldevil:. Good idea to carry an extra spark plug with you so you can easily check for spark when the situation occurs. The result may help diagnose the problem. For me, it always happened in very hot conditions and there was no way I could get close enough to it to pull a plug to check for spark. Extra plug is the answer.
5. Coils. If your pulse generators are working within their specified parameters it could be that one of your coils is not working. If the bike is shutting down completely it's doubtful this is your problem as it should still want to run on one coil (2 cylinders). Lots of info available to check these for failure.
6.Fuel pump. It could be that your fuel pump is no longer up to standards. Mechanic I've talked to thinks that fuel pumps on the 1200s are quite hardy and don't see many fail. If availability is any indication he may be right. Honda don't make 'em no more and try and find an aftermarket producer. Leads one to believe there's no market for them.
7. Ignition Control Unit. When I was trying to find the problem with my '87 the mechanic I spoke to told me this is not the problem you want to have. $$$$$$$ And the nice thing is that there's no test for it, unless someone has devised a way to check the little buggers. Here's the quote out of Cylmer's manual:
Honda does not provide test procedures or specifications
for the ignition control unit. If the ignition coils, the
pulse generator assembly, the gear shift sensor and the
wiring harness are good and the ignition timing is not
within specifications, replace the ignition unit with a
known good unit.
Basically, you check absolutely everything else and if all's well up to that point, it must be the ICU. Don't know how common failure is with these. Maybe others can relate their experiences.
8. Fuses. As already mentioned, sometimes fuses look good but have small cracks that mess with performance when a bike heats up. Main 30 amp fuse would be the one to check/replace. Recommend replacing with a blade type fuse if your bike still has the dogbone fuse. Try finding one of those on the road. Just be sure to use at least 12 gauge wire when replacing.
9.Kill switch. Like fuses, have a tendency to act up under hot conditions.
10. Vapor locking. This may also fall under #3. You may have a situation where your bike is vapor locking under high heat conditions. Again, search the site for info on how to check.
So there's my top ten. I'm sure I've missed some and the next guy will add to the list. Hope it helps. Just be patient and work through it.
You might also want to post your problem with as much specific info as possible on this site:
http://www.gl1200goldwings.com/index.php
They specialize in 1200s. Many are on this forum but there are some real wizards there, too.
Good luck, and don't forget to let us know what it turned out to be. Shared knowledge is shared power.