Small Engines (Lawn Mowers, etc.): Onan Generator, valve lapping compound, jb weld

Question
I have an Onan E450 small portable generator that is old as the hills and of course all the parts for the thing have long since been dis-continued and they are no longer available.

My problem, which was a small one, started out with trash and rust dust that had clogged up the shut-off valve and screen. I had taken this apart and cleaned it very good and replaced it. Then to be on the safe side, removed the bowl on the carb, found dirt in it as well. Removed the carb and found that at some point someone had tried to remove the main jet, which is located in the bowl nut. This nut looks like one from a Tecumseh that has the holes in it for fuel flow into the jet. This jet shows signs of nicks and stuff from a screwdriver or something. Keep in mind that this generator ran perfect before the fuel flow was stopped up by the trash.

I cleaned all the parts of the carb, used a small piece of tag wire for the small holes, used carb cleaner and then air pressure, carb looks almost new, but heres the problem I have:

The engine runs, but is now fuel rich, adjustments on the air mix screw makes no changes to it. If I turn the fuel shut-off valve alittle, the engine will smooth out and run perfect for a few minutes and then shut down. All passages in the carb are clear, no signs of dirt anywhere, just can't control the fuel flow, so how do I solve this problem ?

Charles


Answer
Have you checked E-bay for a different carburertor?

I had a similar problem with one of my mowers.  I eventually found another carb and was able to use the smaller main nut jet to get the engine to run.  Of course it took a while to find the right jet size...trial and error.

If you have a mixture screw you might try lapping the seat inside the carburetor with a pencil, the pointy end, and some fine valve lapping compound.  This will probably only affect the idle circuit.

Another trick I've read about is customizing the origanal jet.  I've heard of mechanics using a little JB Weld or plumbers epoxy putty to fill the original holes and then using some very small carburetor drill bits to drill a new main jet orfice.  I'm not sure if it works because I have never tried it myself.

Let me know if this helps at all.
Eric