|Cleaning out an Exhaust Pipe
on a Moped or Motorcycle w/ a 2-Stroke
|*Warning: this is
dangerous! Do not try this unless you are an
accomplished torch person.
- The oil burned with the fuel
in a two cycle engine leaves carbon deposits inside the muffler area.
deposits can be very thick, and cause the muffler to be completely shut
in some cases. There are no safe solvents that I know of to remove
- If only the tip of the muffler is
plugged, pick it out with a long thin
screwdriver or drill bit.
- If the carbon
is inside the baffle units, it can only be removed by cutting the
muffler in two with a hacksaw, cleaning it and welding it back together.
- The other method is using an
torch. The torch method produces a large amount of smoke and pollution
when done, so I cannot recommend it. It is also easy to overheat
the inside of the muffler, burning out baffles and possibly burning a
through the muffler. I suggest not trying this unless you are an
torch person with a death wish.
But here is how you
- Remove the muffler from the
moped and lay it down on the ground, as it will get red hot and shoot
sparks several feet, so make sure you are not around anything
Do not do this indoors!
- Using the torch, and a small/
medium tip, put the flame very close, but not into, the tip of the
after a few seconds, the tip should be getting red hot. Be careful not
to melt the muffler tip.
- Keeping the torch tip very
close to the muffler tip, pointing the flame inside the muffler, turn
the acetylene knob so the flame goes out, and turn up the oxygen knob
increase flow into the muffler. This will cause the carbon heated with
the flame to burn up, and you can regulate the speed of the burn
to how much you increase the flow of the oxygen.
- To much oxygen pressure
and you will melt your muffler into a puddle, so be patient. A red
hot band will slowly move along the muffler, slowing down in the very
areas, and the red hot area will go away when the muffler is clean.
- If a lot
of globs of molten metal come flying out, you are getting it too hot!
- It is possible to get it too cold
and the flame front will go out, so the best results come when you heat
it so there is a good red spot, then slow a bit then heat it up again
minute or so. You must not stop flowing oxygen until the muffler is
cleaned out, or you will need to restart it again with a flame.
- If a muffler
goes out, it can be hard to get the flame burning again since the
closest to the tip will have been cleaned off first. In this case, you
may need to punch a hole in the side of the muffler to get a fresh
then weld it shut when you are finished.
- Some mufflers
cannot be cleaned in this way, a sound deadening material inside will
into glass marbles, and they will plug the muffler tip from the
inside untill you cut it in half to remove them. So, you may as
cut in half at the beginning and get it over with. Yamaha
are notorious for this melted packing, for sure the Razz, Zuma and
Most honda mufflers, like the Spree, Elite, Express, and pa50 respond
to this treatment.
- The exhaust port is
also a place to look for carbon buildup. You should be able to look
the exhaust port with the muffler removed and see the piston. The light
coating of carbon that lines the port is not the carbon to be concerned
- If there is a buildup, it will be
right next to the piston, and in fact acting as a part of the cylinder,
so the hole the piston is seen through is much smaller than the hole at
the end of the port the muffler is mounted to. It is
possible for an exhaust port that should be a 1" diameter all the way
the piston be reduced in size to 1/4". Most times this carbon
can be removed by chipping it away with a small screwdriver or file,
carefull not to scratch the piston.
Scooter Therapy Inc
12 North Few
Street | Madison,
1-608-255-1587 | E-mail
12 N. Few
9-6 Saturday, 10-3 CST