See the other comments about the threaded holes breaking out, the
high temp and plastic gas tank, etc.

I have seen the add on kits at my power products dealer, usually
quite expensive.

Two suggestions: Make a flange mount (don't use the pipe thread
hole) with a 90 degree sweep elbow. This elbow will get VERY hot
so use some heavy wall tube. Braze on a 12" length of the exhaust
type flex hose from the auto parts store. Run it off to a
standard auto muffler. There is a standard replacement size that
is about 4-1/2" thick by 9" x 18" long. Mount the muffler solid
to the generator frame, add a suitable heat shield.

If you want to make a decent tubular muffler: take a suitable
diameter exhaust tube, make a saw slot in the midle, insert and
weld a plate as a full plug. Drill some 3/8" or 1/2" holes
through the tube on both sides of the plug. Get two suitable
washers and a larger tube, weld it up. Exahust gas goes in,
through the first set of holes, into the space between the tubes,
out through the holes, then out.

Ernie Leimkuhler wrote:

I bought a Coleman Powermate 5000 a few months back.
It works fine for the ocasional location welding I need to do.
It only has to power my inverter.

My only problem is the noise.
It has this tiny little spark arrestor, and no real muffler.

I am hoping that one of you guys has successfully added some kind of
muffler from a moped of small motorcycle.

The engine is a 10 hp Tecumsa Sno-King engine as used on snowblowers.

http://www.colemanpowermate.com/gene...45004_17.shtml

I am looking for a simple cheap solution, but I don't know enough about
small engines to know if the muffler provides some kind of back
pressure to the engine.