EXHAUST

I have a hole in each of my exhaust pipes just below the bend about 3/8 inch round. They don't apear to be random holes is this normal? I have a 1982 Yamaha 750 maxim

 

I have tiny maybe 1/8" holes in mine I think they are some sort of drain for moisture yours may have just naturally englarged from rust.

 

no they are not rusty and are very delibrit... just can not think they would put holes in the exhaust before the muffler to drain what???

 

They drain water from the exhaust process. Gasoline is a hydrocarbon (the key here is hydro), and when gasoline (hydro) combines with the air (oxygen) while burning, H2O - water - is formed. Instead of gathering in the bottom of the pipes until it gets sprayed out the muffler, drain holes are placed in pipes in almost every type of vehicle you can imagine.

In any case, at 3/8 inch, yours sound rather large.

 

You are trying to tell me the factory put holes in my exhuast pipes to let the water out from the hydrocarbons made from the dinos I burn. Unless some one else comes up with this cockamamy story I will have to pass. There has to be another reason. sounds like I have an exhaust leak and I know where it is comming from. Can this be real?

 

Ditto on the drain holes, Mine has them too. Also on my Virago.

 

I've noticed on just about all my metric bikes I've owned. There are drain holes in the exhaust system on most all of them. Not cockamaymee at all. Just a good idea.
Now that I have switched to an after market system of my own fabrication. the bike spits out a bit of moisture when I fire it up if there is humidity in the air (or if it get rained on) I may have to drill a hole on each side of the exhaust system to eliminate the spitting. PD

 

i've noticed holes at the bottom of mufflers, sometimes with a split pin dangling out on two strokes never seen them on four strokes, if i had holes in mine i would be looking for a welder.

 

Yes, that's what he's telling you and it's for real. Those are drain holes.

If the factory didn't put them in they'd show up on there own after a few years due to condensation settling in the low points of the exhaust system and causing it to rust through. :wink:

 

It sounds like you're talking about these holes:



If so, I believe those are called "bungs" and are used to insert an exhaust gas analyzer for tuning purposes. They should have plugs in them though; if yours are open then yeah, you definitely have an exhaust leak. :wink:

 

Very prevalent occurence on old CB series Hondas from the 60s-70s era, for exactly this reason, if I remember right. I remember replacing 2 sets only several years old due to internal rust.

Muffler drain holes are a necessity on motorcycles, as noted in the posts above. Water vapor is a product of normal combustion.

 

Yeah, those arent for draining or Yam wouldnt plug them with bolts. Just access holes for the analyzer. You should have to worry about water draining, unless you have the habbit of cranking your bike and driving it 20 feet and shutting it down. It'll get plenty hot enough to boil water in a min or two.

 

Ok, I'll confirm the "cockamamy" story. Part of the combustion process exhaust gases include (drum roll here), H2O! This is normal but in the start up and early (or cold) phase of warm up, there is a tremendous amount of water vapor present in the exhaust stream.
Now I know you are familiar with the condensate on the outside of your chilled beer bottle so just imagine what happens to a cold metal cylinder when hot gases are passed through it. Bingo, condensation from the ambient air (the air around us has water in it in case you didn't know). Now remember, the exhaust silencers (or mufflers) have a dual wall construction. This means that as the warm gases pass over the cold metal of the inside tube, condensation will occur on the outside (and to a lesser degree the inside) of the inner metal tube. This water will pool inside of the outer metal can (the pretty chrome unit you see) and rust it out unless it is allowed to be expelled somehow. Ergo we have drains. And if you ride short distances regularly, you will develop lots of condensation as the exhaust will never quite heat up enough to evaporate the condensation. This is why I see LOTS of rusted out holes in the bottom of exhaust mufflers and collector tubes. Short commutes are the primary reason for this early death.
So check out the chemical composition of exhaust gases from an gasoline operated internal combustion engine, I think the "cockamamy" story might be banished quickly with a little education.
(hint, there is hydrogen in the hydrocarbons of the fuel and plenty of carbon monoxide along with it. All it takes is a high pressure condition to get these two molecules to get together and combine, releasing heat and water in the form of vapor)

 

Robert I understand the prosess of condenstion. but as showen by the pic above these holes are not put there for that purpose or they would not have pluged the holes. So as I said to start with holes in the exhaust before the muffler is a cockamamy story.

 

The Hex Bolt Heads at the bottom of the Front Headers are for hooking-up the Bike to an Exhausut Gas Analyzer Machine.

Generally speaking, the "EGA" Machine that Yamaha put in the Dealerships back when these Bikes were new, was used to tune-up the Bikes to conform to Exhaust Emission Standards of the time.

For awhile, Yamaha maintained the machines.
Then, they gave the maintenance requirements for keeping the machines accurate and usable over to the Dealership.

They became to expensive for the Dealerships to maintain, so just about all the Dealerships rolled them over to a corner of the shop and let them start collecting dust.

The Hex Bolts were never treated.
They also weren't hardened.
Consequently, the froze solid and became permanent fixtures.

If you can get them out ... riding around with those little holes open gives you a growl and a backfire that makes the Bike sound like you are running performance exhaust.

 

I see where you are coming from. The picture (as the saying goes) is worth a thousand words. Now that we are on the same page as to which holes, you are correct. Wish the picture had been available earlier, I might have gotten the chance to avoid writing my response.
Those bolt holes, as Rick mentioned, to were for the dealers exhaust gas probe.

 

I am going to try and find the correct size bolts and plug the holes and see how big a diff it makes in the sound and if any in proformance.

 

Hey guys ! I got a third set of 4 mystery holes !!!
The big ones are analyser probe holes,
The small ones are water drains,
These 4 are 2-3 inches from the head, on the inside radii, just as the bend starts. They point down. They are about 1/16. Since I know the answer, this is a test. . .

It's on aftermarket pipes- - Seca 900. Fotos later.

 

Are your mystery holes for temp probes?? kinda sounds like it. I need to get a setup for my sled as it is big bored and I am running a shaved head.

 

Drain Holes. The mufflers are dual-wall and need them, the plugs on the pipes are EGA attachment points. What CAN happen (happened to both my SR500's) the INSIDE pipe can crack or rust and then exhaust comes out the drain hole and sounds nasty. (I simply had the drain holes welded up with stainless rod when this happened.)

 

they shouldn't be holes, they should be pins.

 

Wizard, you may be on to something here- - maybe I don't know the answer. My idea was the PO put them at that exact spot to suck in a little air, which causes some unburnt exhaust to burn, ultimately for better scavenging and more horsepower. This is a circle track trick I read about.
Then the PO welded them up with neat little welds. I got welded holes.

So tell me about these pins.

 

Well I have now officially been insulted in a place that I never expected! And Robert, you are a true gentlemen among gentlemen.

As I said, the "story" of water forming as a product of gasoline combustion is true, grim's holes seemed rather large by description and the pictures, as Robert says, say it all. If there are any folks out there that still think that water drain holes are silly, take a look at most mufflers on most cars.

One thing I am not, is a teller of cockamamy stories or a passer-on of BS. If grim really thinks that most people are good for nothing as his tagline clearly states, why is he asking questions? It may be good practice for us all to send photos.

 

PSteele, while I appreciate the comment, why not let the slight pass?
It is easy to fling poo but it is a true testament to chivalry if we let those who chide others with snide comments enjoy their barbs without returning fire. I'll admit that some comments do get my goat but I do hope that my comments in return attempt to instigate fraternity rather than more unnesessary shots. Wanna join me?
And I'll support the heavy use of photos, I just wish we could get this site to host a larger pixel display so we wouldn't be dependant upon other servers to host pictures (we lose good shots after awhile because of this).

 

Grim,

The picture supplied by MaximumX is showing some bolts just before the heat shield. Are these the "holes" that you are talking about?

If so, then you should check to see if they are threaded and if so, put new bolts in them.

As for the "cockamamie" story that PSteel relayed, well, this has been discussed already and several people have supported the theory of small holes to allow for drainage of condensate.

 

Mr. PSteel if I was the one you were refering to that has insulted you I am truly sorry and never ment it that way. And my tag line clearly states what I thought was humor. and the KEY words in your quote here are HOLES,SILLY AND MUFFLER. Muffler being the main one. We were talking about holes in exhaust pipes before the muffler. Holes in mufflers are common but not before the muffler. Seems like no sence to put a muffler on if you are going to drill holes in the exauhst before it gets there.

And Mr. Robert I do not as you say sling poo nor do I make snide comments and I have never chided anyone in my life. If the word cockamimi is taking unnessary shots then in the future I will refrain from using words of this nature. also if you feel that I have slighted you I am truly sorry.

I did not come on this forum to start an uproar I just wanted to know about some holes that I knew should not be there not open anway.

 

OK guys - let's chalk this one up to experience and let'er go, as my grandma would say. Ain't worth losing sleep over.

To say that I enjoy this forum would be an understatement and there is no way this old soul would want to jeopardize that enjoyment.

What say grim - square? Shall we drop this 'hole' conversation?

 

I like the way you worked "hole" in there. Hell yeah! I swear I never ment it the way it came out. I have a forum of my own and I see how things get mixed up. I as well enjoy this site and never want to cause hate and discontent. I will try harder in the future to not be such a smart ass. but some times I do slip. So you guys keep me in line if I start to get out of hand.

 

I'm putting it to rest.
You got close to the edge ... but didn't cross the line.

Now, back to our regular programming.

This thread is locked.

Say goodnight, Gracie.
"Good night, Gracie."