Motorcycle Repair: Engine trouble Honda GL 1500, honda gl 1500, new spark

Question
Hi !From 800-1500 rpm on any gear and at constant speed the engine varies in thrust. It seems to me that all cylinders doesn´t work properly. If I increase  speed or exeed 1500 rpm it´s ok.
There are new spark plugs mounted.
Best regards from Sweden / Ingemar

Answer
Hi Ingemar,

Surging engine is caused by cantaminants in carburetor. It's likely fuel in the carbs has varnished from storage.

When the idle/pilot jets and passageways become  obstructed, engine idle surges in a steady hi/low cycle.

Requires thorough carb cleaning and sychronization to restore proper performance.

Respectfully,
Mark Shively