Motorcycle Repair: Odd sound from engine, fuel stabilizer, odd sound

Question
I have been letting my 1990 Honda GL1500 set around much too long.  It now has fresh gas and it ran fine about a month ago.  I changed the oil (my first time ever doing that by myself) and overfilled it by 1/10 of a quart.  I let it sit for another week or so 'til I got new tires on it.  Suddenly low-end performance is very poor, but once the engine is revved, it's better except for an occasional bit of surging.  I had to adjust the idle screw to make it run at an idle.  Sounds a little like a deisel truck when it's revved from an idle, as well.  Any ideas?  Thanks!

Answer
Gil, letting bikes sit without fuel stabilizer in them can cause lots of problems with the fuel system, which is often the source of these issues. When the fuel tank is left with less than a full tank of fuel, it can also condense water from the air space, which will get pulled down into the carbs and block the jets. Lots of possibilities for problems, really...
http://www.goldwing-world.com/1500_recalls.htm
http://archive1.gwrra.org/discus4/messages/3747/11780.html
Search these sites for possible solutions.

If you have never changed your oil before, I don't know how much info you can absorb in doing troubleshooting issues on fuel or electrical problems.

The basics to check are: compression, fuel supply, ignition timing, spark plug condition. It sounds like it has dropped a cylinder due to fouled spark plug or perhaps an air leak or fuel bowl contamination blocking an idle circuit. The carbs are also fitted with starter circuits, opened by the choke cable which could be sticking open or closed.

Pull the spark plugs, lay them on the cylinder head, attached to the wires and then turn the motor over to check for spark at all 6 of them. At least inspect each one for signs of either being fuel fouled (over choking) or dry due to no fuel to the idle circuits. The engine will get lumpy sounding if one or more cylinders are not firing at idle. Also the primary chain will whip around and rattle when the engine is out of dynamic balance, which will happen with fuel, compression or ignition system issues.

Basically, you have a 2 wheeled Honda Accord, so you probably should find a qualified mechanic to look/listen and  diagnose this problem correctly.

Bill Silver