Natsumi-San, you probably mentioned what it was, but the translator didn't pick it up. Was it a mechanical problem? Back when I had my 1982 Honda CBX 6-cylinder, the cam chain tensioner went out, and it started rubbing against the inside case; The oil was full of aluminum "glitter", and since those "CB series" Hondas used plain bearings (as opposed to the Kawasaki KZ engines which used crankshaft roller bearings), it pretty much destroyed the engine. Also, all of those old ignition systems used "Capacitive Discharge" coils (CD Coils), and you had to be careful and not burn up the module by letting the spark plug gap run too wide; the 2-valve KZ engines only had one spark plug in each cylinder, but the combustion chambers were "hemispherical", which meant it was hard to get the cylinders to give a complete and efficient burn. We tried running spark plug gaps as wide as 1.5 - 1.6 mm to make more power, but it was very hard on the modules (but believe it or not, with fresh plugs and a 1.5mm gap, you could just let the clutch out in 1st gear, and the motorcycle would just pull away without even giving it any throttle lol). I hope everything is ok with that beautiful motorcycle!