The following is a repost:
Generators that turn 3600 RPMs like my Coleman 5000 / 6250 with Tecumseh HM-100 have a residual magnetism that remains in the armature. When these units start to generate power that residual magnetism starts the initial flow of power. The current flow from then on increases that residual magnetism until it reaches a maximum. IF the generator sits too long it can (may or may not) loose the residual magnetism. IF it does loose the residual magnetism you will have to ZAP the armature with some source (electric current from a 6 or 12 Volt battery, or a huge magnet near it) to get a residual magnetism started. It is interesting that people who have done this say that if you have a light bulb on the output of the generator, it slowly increases in brightens. This is because the output current causes an increase in residual magnetism, that causes an increase in output voltage and current, that causes an increase in residual magnetism – exc. -exc.
So if you do not want a 3600 to loose its residual magnetism you should run it once in a while. How often is anybodys guess, and the time interval to loose the residual magnetism probably varies with the manufacturer, and maybe even with individual units.
If there is not an outage, I now run my Coleman Powermate about twice a year, and so far have never had to zap it.
Then there is the problem of keeping the carb clean. The small idle circuit air hole just behind the choke plate (on the floor of the air passage before the main jet) tends to get clogged up. Sta-Bil or Redline SL-1 in the fuel helps fight the ethanol in the fuel that aids this clogging. WD-40 down that hole before storage is a good idea.
I have a Generac ix2000 that I ran Stabil and then sprayed WD-40 on the carb idle circuit, and main jet. I also foamed the cylinder with Sta-Bil Foaming spray oil, and pulled the rope a few times with the spark plug out. Then put the spark plug in and lightly pulled the rope so it stopped on a compression stroke so moisture from the air can not condense out of the air and build up in the cylinder, and also the springs for the valves are not in full compression. I will leave this gen-set sit like this for several years if it is not needed for an outage. This generator is not a 3600 RPM unit and to the best of my knowledge does not require residual magnetism to start. However if it did not generate any electric when first used I would hold a huge magnet near the electric generation section to initate it.
It is a good idea to pull the bowl off after you run it dry, so you clean out any crud and also get the last bit of fuel out of it.
Probably the best fuel tubing is Tygon fuel tubing. You can get it from McMaster-Carr. There are several kinds of Tygon tubing. The kind you want is Tygon F-4040-A , and McMaster-Carr sells it in just about any ID you could use.
McMaster-Carr has a special deal with UPS. Expect you package to arrive at your door in one day, two days tops. And the shipping charge will be low.
