Motorcycle Repair: 1983 yamaha 650 maxim, plug gap, heat ranges

Question
could you tell me what the correct plug gap is for this engine? i haven't been able to snag a manual.  thanks.

Answer
The plug gap can be within a range of .025" - .040" and be close enough to run OK. If it's an older bike with weak spark you may have to experiment with it and see what starts/runs best for you. Different plugs types have different heat ranges and are more or less prone to foul if it uses a bit of oil. If you ride hard and long you will want to use a colder plug, if you ride gently and for short distances you may want a hotter plug. You should check the plug after a period of time (~1000mi) and see what it looks like. Here is a web page with some examples of different plugs and conditions. Even though these examples are in a small engine they will be very similar and will help you judge what's going on in there.

http://fumc-genesis.org/fortune-diy-sparkplug-replacement-4-5-hp-mtd-yardman-sno