Motorcycle Repair: I just picked up a honda 1980..., crankcase blowby, bill silver

Question
I just picked up a honda 1980 cb650.The bike starts hard,when I put it in choke it does not seem to work. The bike burns a little oil when warm.The plugs are black, like running rich.What should I check to see if it has bad valves or rings or just the carbs are bad? thanks

Answer
Steve, the choke cable may be seized up internally. There is an adjustment at the base of the knob for cable tension.
The black cap below the knob can usually be turned to change the tension on the cable housing. If that doesn't work then the cable should be removed and lubricated with some light oil, if possible. It may need replacement after 25 years.
You don't mention the mileage on the engine, but after 25 years the valve stem seals often get hardened and fail to control the oil past the valve stem seals. You can remove the head on these engines w/o engine removal.
Remove the plugs and do a compression test with the throttle held open. Standard readings are around 170 psi. If the bike has been buring oil for awhile, the readings could be higher due to carbon buildup on the pistons. If lower than 150, then the rings could be worn and/or valves not seating properly.
The function of the mechanical spark advancer should be checked, in case it has locked up. That affects the ignition timing advance which influences the carburetor functions.
No doubt the carbs could use a cleaning, but check everything else first, including the air cleaner element, which could be plugged up. If there is a lot of oil in the air box, that is a sign of crankcase blowby past the rings.

Bill Silver