Odd model designation as "ZX" normally designates Kawasaki full-fairing sport bikes, and the only one of those in production in 1984 was the original Ninja 900. The fact that your spark plug number starts with a "B" indicates that it is not the smaller 10mm plug that is in use nowadays. Consequently, I'm going to go out on a limb and guess that we are dealing with a KZ 750 or GPZ 750 air-cooled carbureted engine, and presumably not the fuel-injected GPZ 750 Turbo that was also in production in that year. If I am wrong then please correct me.
Anyway, based on the above assumption, we are dealing with an air-cooled engine that is carbureted and has no cooling fan. They're always gonna run hot when stuck in traffic.
Few things:
- Are you using premium fuel? What octane rating? Try Shell V-power 91. (PetroCanada/Sunoco 94 may be too oxygenated - I've had issues with it.)
- Are the cooling fins reasonably clear of debris (accumulated dirt, bugs, etc)? If not, clean them out.
- What do the spark plugs look like when you take them out? They give some indication of what is happening inside the engine.
If the spark plugs look black with carbon, it's possible that the engine as a whole is built up with carbon deposits as a result of running too rich and/or excessively long use of the choke during warm-up and/or clogged air filter and/or short-trip low-load driving that never gives it a chance to blow the carbon out.
If the spark plugs look white with little deposit of any sort on them, you could have a lean condition, which can lead to detonation. This could indicate vacuum leaks (are the rubber boots between the engine and carbs in good shape? how about the rubber boots between carbs and airbox?) or wrong carb settings.
If the spark plug has an almost melted look to it, possibly incorrect heat range. Try BR10ES.
