my 89 gs was running very well for about 80 miles.   just after that it was a bit sluggish and seemed like it was struggling for fuel but it came out of it.  i parked the bike for about 1/2 hour.  when i came back and tired to start it she would start but at full throttle it was a bare min idle.  then it would stall.  i let her sit for a couple of minutes pulled on full throttle for a second before i hit the ignition and she started right up and ran well the 3 miles back home.  the only leak i can find is a little bit of oil around the head gasket.  also the spark plugs were all gummed up when she got a tune up about a month ago.   so i wonder is it fuel problem ie petcock, vaccum hose or carb?  maybe the airbox or who knows.  so i am open to suggestions/opinions.  i just don't want to end up stranded.

Maybe three issues at once ?

Sounds like typical fuel starvation, dirty air cleaner, and flooded.

The lagging power = starvation (use PRIME and see if that helps)

Not easy starting = aftermath of starvation

Starting only using WOT = flooded

Then it rode fine 3 miles home = the bowls were filled again during the startup process, or had just enough not to annoy you on the way home.


My 2 c

Have you had the tank off lately? Sometimes the tank petcock can be very fussy about how well the valve is aligned on "on"... just  a thought.