Motorcycle Repair: Carb problems, piston cylinder, fuel valve

Question
Chris,
I bought a 1982 Yamaha XJ650 Maxim that sat for about 15 years.  To make a long story short, I was able to get the bike running after a good carb clean.  The bike runs good but there are two problems I can't seem to figure out.  First, I can't get the bike to idle under 3000 rpm's.  The idle adjust screw is turned all the way out and it will not idle down.  I double checked all the jets were replaced properly and the floats all work proper.  Second, When the bike sits for awhile it won't start unless I give it a shot of starting fluid, then it starts right up and runs.  After it is warm it will start right up but if you let it sit for a 1/2 hour it won't start without the starting fluid. I have cleaned out the fuel valve and it seems to work fine.  It is like the bowls are not getting gas until there is a vaccuum from the motor.  Please help!
John

Answer
High John.

Start by replacing the fuel line and resealing the tank.  You may need to have the carbs recleaned.  Also check to make sure that the floats are working properly.  There should be test proceedures in the repair manual.

Check the plugs.  See how they are.  Is the bike running rich or lean?  The mixture is probably set wrong, if you removed the jets, then that is likely the case.

Check the manifolds.  Chances are, if they are the originals, then they are leaking air into the system, leaning out the mixture and causing problems.
Make sure that they are tight to both the head and to the carbs.  If they are, then replace them and make sure that when you install the new ones, use a good gasket sealer where they connect to the head.

Check the compression against what the specs in the manual say the compression should be.  If it is lower than spec, then make sure that the valves are set right and recheck it.  If compression is still bad, then you could need new rings or other piston/cylinder work.

Start with that and let me know what you find.
Good luck and ride safe.
FALCON