Motorcycle Repair: rough engine, float bowls, fuel starvation

Question
Hi Bill,
I just bought a 1971 Honda 350 SL (scrambler)and it ran great last weekend, but today I took it out and after about a 1/4 mile it was running really rough and only on one cylinder (I think). After a bit it came back to normal for a while then did it again. It feels like fuel starvation. It's new gas in it. Should I clean the carbs or what? Thanks in advance for any suggestions!
Ross Mason

Answer
Ross, I would always go through the whole bike and check all tune-up and fuel system components for proper function.

When bikes sit for years, the old gas will do all kinds of stuff to the fuel system. Check the gas cap for proper venting, the fuel petcock (fuel valve) for cleanliness, as well as the bottom of the fuel tank. From there, remove the carb float bowls and see what is lying in the bottoms.
From there you can sort out what else to do to clean them.
Running the engine with a leaned out carb is asking for piston seizure problem.

Before too long, I would suggest that the ignition timing be checked along with the mechanical spark advancer that is behind the points plate. A valve adjustment check would be a good idea, too.

Bill Silver