Okay, Book 2 of the saga. (I hope this isn't a trilogy.)
Cleared the bowl vent, changed the oil (very thin and a lot of it - thanks for suggesting it, unclecharlie), checked the cylinders for standing fuel (they were dry), replaced the air filter, charged up the battery and started it up. It caught and idled just fine, no surging or popping.
Saddled up and took a lap around the park to see if it'd keep running. I could feel more vibration from the engine than I remembered, and it didn't have any power. It tried to stall taking off from a stop a couple of times. I took it up the street to get fresh gas and could barely make 40 mph. On the trip back it would surge and backfire frequently, on the left side, with or without choke.
In the course of looking for the original fuel leak I had replaced both float needles. I had never checked the bowl fuel level before this started, but with the new needles and a clear vent both carbs level out about 1/8 inch above the line where the bowl mates to the carb body.
When I checked the cylinders I noticed both spark plugs had a dry sooty appearance, but not heavy.
After removing the carbs about three times over the summer, I noticed the cement where the rubber boots attach to the airbox has pulled free. Without pulling on the boot you can't see it, but if you twist or pull on the carbs you can see the shoulder of the boot pull away from the airbox slightly.
So far I'm planning to put some carb cleaner (Sea foam if I can get it) in the fuel tank and replace the spark plugs. Is there anything else I should look at or try? Would the lack of a glued seal on the airbox boots allow enough air entry to behave like a vacuum leak? How about if an airbox drain plug is missing? (They were really slippery when I took them out to drain the box a while back.)
Dave
