Motorcycle Repair: Hi idle problem, yamaha 1300 venture, vacuum leaks

Question
I HAVE A 1993 YAMAHA 1300 VENTURE V-4  WHEN YOU GIVE IT THROTTLE and turn it back down,IT IDLES BACK DOWN VERY SLOWLY. IT ISN'T THE THROTTLE LINKAGE OR A VACUUM LEAK,I'VE CHECK ALL THAT. IT DOES HAVE A VACUUM ADVANCE HOSE THAT GOES TO A SOLID STATE SPARK ADVANCE BOX. WHEN I REMOVE THIS HOSE, WHICH IS ATTACHED TO ONE OF THE INTAKES THE PROBLEM GOES AWAY.

WHATCHA RECKON?


Answer
Mike,

if you are sure the linkages are okay and no vacuum
leaks, then it may be your stuck in full advance
due to a plugged vacuum hose or a faulty
advance unit. Try putting a timing light on it
and see if it fires on the timing marks or
if it varies alot. If you unplug the advance unit
you may be okay around town but at higher
speeds you will lose power and maybe overheat.
Check your plug color for clues, plug
color charts are online at NGK etc.