78 GS550 Pin Hole in Muffler

[Guest]

I should take photos and post them to make it easier to see/understand, but until then, I'll just ask the question. So in the rear end of my right muffler, an inch or so from my exhaust pipe hole. There is a small pin hole, not much larger the 1/8th of inch. What is this pin-hole function as?

[chuck hahn]

Condensation drain. Condensation forms after shutting off the bike and as the pipe cools it condensates.

[Steve]

I have usually seen drain holes at the front of the muffler, which is usually the lowest point in the system.

There <might> be an additional one near the back, but there is ALWAYS one at the front.

.

[TyeGuy]

I found a photo of the hole in my exhaust. IMG_4329.jpg

[TyeGuy]

Condensation drain. Condensation forms after shutting off the bike and as the pipe cools it condensates.

Would you say that its more of an ventilation hole rather than an actual drain hole? Much like cracking the bathroom door when taking a hot shower? I can't image condensation building up enough for it having to actually drip out of a hole.

[chuck hahn]

First i saw this picture after i made my post. Steve is correct on a drain hole being at the front..as this is what i was thinking when i posted. That ones probably for evaporation vapors also???

[bwringer]

Would you say that its more of an ventilation hole rather than an actual drain hole? Much like cracking the bathroom door when taking a hot shower? I can't image condensation building up enough for it having to actually drip out of a hole.

You don't have to imagine it -- you can see it every day. On any chilly morning, look at the tail pipes of cars and bikes in traffic. The white "smoke" you see is water vapor condensing when it hits the cool air, and you'll also see liquid water dripping out if they're not completely warmed up yet. (Water from exhausts is an additional traction hazard at stoplights, too...)

One of the normal products of combustion is water, and until the entire exhaust system gets hot, some of the water will condense from vapor back to a liquid before it reaches the exhaust outlet.

Over on the V-Strom forum, there's a new panic thread every fall when it gets a little chilly and someone notices that they see "smoke" (actually just water vapor) emerging from only the left exhaust on their DL1000. This happens because the exhaust system traps a little water on the left side when the bike is parked on the kickstand, so it takes a little extra time for the water on that side to evaporate.

OEM mufflers in cars and motorcycles usually have a small weep hole somewhere to allow water to escape. It's not much of a concern closer to the engine, since even on a short trip it gets hot enough to evaporate any water. But at the end in the muffler, it can take many miles to get hot enough (or it might never get that hot on a cold day), so you need a weep hole so the water doesn't get trapped and cause corrosion and/or freeze.