Motorcycle Repair: 81 Honda CX500 only runs decent with choke on, honda cx500, simptoms

Question
Hi Chris,

I am reviving an 81 Honda CX500 for a friend.  It has been
stored for three years.  It started up fine and with the
choke on it runs OK, bogs occasionally.  If the choke is
turned off the bike bogs badly at low and mid RPM.  I
cleaned the carbs after this 3 times and no change.  I am
surprised how much affect the choke has.  The carb pistons
were dry, do they need to be lubricated, and with what?  
One of the valves is rattling and I've heard that can cause
same simptoms, could that be the only problem.  Any help
would be greatly appreciated.

Thanks in advance,

Mitch  

Answer
Hi Mitch.

During the restoration did you reseal the tank?  You could have varnish in there which is contaminating the carbs.

The carb pistons should not be sticking at all.  There really isn't anything that is needed to lubricate the pistons at all.  If they are sticking, then the carbs could need a proper rebuild.

Check the manifolds for leaks and cracks as well as the seals to the heads and the seals to the carbs. Replace the manifolds if they are cracked.

Synchronize the carbs.

Check the air filter.  If it's dirty, then replace it.

Check the valve timing and gap.  Make sure that it's right.

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