Motorcycle Repair: 1983 honda shadow vt 500 c, vt 500 c, vacuum leak

Question
I hope your familliar with this bike. I have done mechanics for awhile but I have gotten stumped on this one I have a shadow 500 that is hard starting for one ,choke on hits,choke off hits,choke on hits a few more times,choke off hits a few more...after a bit it will eventually fire off.I let it warm good and take off it seems to have power for a sec. then loses it under a load.sitting in nutural it will rev just fine and no misses but as soon as i take off it goes guttless again.choking while riding seems to help a bit. So I went through the carbs and syncronized  them but it didnt help.If you have a possible solution I would be greatfull.

Answer
Keven,

Perhaps, it isn't getting enough fuel from the tank. There is a screen inside the tank on the end of the petcock tube. Not uncommon for them to clog up after 22 years.
Below that the vacuum operated diaphragm for the petcock may have a hole in it, which gives a vacuum leak and reduces the fuel delivery to next to nothing. Sometimes the wrong fitting is used for the vacuum hose on the petcock which fails to activate the diaphragm.

Do be sure that you have good spark at all the plugs. Spark advance is electronic, so not much to do about that unless the module fails.

Bill Silver