Background: My new-to-me 1988 Hurricane began running rough, when hot, a few weeks ago. Cylinder number three would foul the plug, and it became a rough running three-cylinder with a very rich, sooty exhaust. Then it would leak fuel from carb #3 - the fouled-plug cylinder. So I thoroughly cleaned the carbs and rejetted back to stock. Fired right off and ran great around the neighborhood. Planned a short 50 mile test-ride, and once the temp came up and the fan clicked on, the roughness and power loss started again... Back to the drawing board.

Solution: So I studied my Haynes and Clymer manuals. And read dozens of posts on this forum. When cold, the battery was at 12.5V, and the bike would crank, start and run sweet. And while cold, the battery would charge at 13.5V at 5,000 rpm - passable, but not great. Watching the voltmeter while the bike warmed up, it became clear that the charging system was under-performing as the temp climbed. By the time the fan clicked on, the charging voltage was 12.20 and dropping. The R/R passed the checks in the manuals (and in the various threads). The connectors were good, clean, and tight. Hoping for an easy, illogical fix, I installed another R/R included in boxes of parts from the P/O. No change. But I did notice that the R/R in the bike when I bought it was an aftermarket one and practically brand new... So the P/O clearly thought there was an issue there somewhere.. Next test: Alternator resistance: 0.6O Ohms across two of the three yellow wires. Open circuit between the third yellow wire and either of the other two yellow wires! Last check, started the bike with the alternator connector un-plugged, and found no voltage from the same suspect yellow wire (the other two provided 30vAC at about 4,000 rpm). eBay to the rescue with another stator.

In summary, the weak charging system was the result of a failed stator. Not enough juice to spark the plugs when hot, when load was the greatest with the fan on. But why the fuel leak? That remains a mystery, as the float valve in #3 was clean, working properly, and the float heights were all at 8mm. Unless the fuel pump relay was erratic at low voltage, causing the pump to run on - well, if anyone has insight as to this aspect of the issue, I'd love to learn more about it!