Will removing baffles completely on my 4-1 hurt anything?

[HiSPL]

Yup.......

 

[Detman101]

Straight pipes do not automatically mean no back pressure. Length of the pipi and curves also effect it

This is what I also noticed Scotty.

With the can off of the mac 4-1 exhaust the bike seems to pull harder but it also uses up more gas and is hella loud. However, the bike runs just the same and the plugs look good after I rejetted to be safe.


When I gut the cans off of the stock exhaust the bike wouldn't run 2 miles without sputtering out. That experiment is what led to this photo.

Having to stop every 2 miles and being stuck on the side of the highway in the dead of the night is no fun. I bought the 4-1 right after this adventure in exhaust modification.

 

[Detman101]

A week?? Don't worry, I highly doubt you even came close to harming the exhaust valves. What WILL burn valves, is improperly jetted, drag piped exhaust with extended "highway" rpm usage.

Awesome, Good thing I rejetted the mains. Doing the chain conversion today so the can goes back on for transport to my buds garage.

 

[matterri]

I bought a set of Mac replacement mufflers for my GS850GL chopper project. I plan on cutting the baffles out of them for no other reason than to make the bike louder. Hopefully I won't hurt the image of the motorcycle community in my area for doing this \\/ . (like it'll even come close to the amount noise from the harley's) I'm still not convinced either that no baffles will hurt my engine or valves for lack of backpressure. From the reading I've done, most of this "backpressure" stuff is just an old wives tale. I'm sure I'll take some criticism for that.8-[ Seems to me any restrictions in the exhaust on any engine, such as mufflers and baffles, just hurt flow. I'm no engineer or bike mechanic, this is just what seems right to me. What about the old school Honda CB chops that run straight pipes about half the length of the bike. Short and wide open. What are some thoughts on this??

 

[Detman101]

I bought a set of Mac replacement mufflers for my GS850GL chopper project. I plan on cutting the baffles out of them for no other reason than to make the bike louder. Hopefully I won't hurt the image of the motorcycle community in my area for doing this \\/ . (like it'll even come close to the amount noise from the harley's) I'm still not convinced either that no baffles will hurt my engine or valves for lack of backpressure. From the reading I've done, most of this "backpressure" stuff is just an old wives tale. I'm sure I'll take some criticism for that.8-[ Seems to me any restrictions in the exhaust on any engine, such as mufflers and baffles, just hurt flow. I'm no engineer or bike mechanic, this is just what seems right to me. What about the old school Honda CB chops that run straight pipes about half the length of the bike. Short and wide open. What are some thoughts on this??

Well, I know from experience that Backpressure ain't no old wives tale.
It, or the lack of it, was the cause of me taking 4 hours to get from baltimore to Silver Spring the summer before last.

 

[matterri]

Why?? Please explain.

 

[scotty]

This is what I also noticed Scotty.

With the can off of the mac 4-1 exhaust the bike seems to pull harder but it also uses up more gas and is hella loud. However, the bike runs just the same and the plugs look good after I rejetted to be safe.


When I gut the cans off of the stock exhaust the bike wouldn't run 2 miles without sputtering out. That experiment is what led to this photo.

Having to stop every 2 miles and being stuck on the side of the highway in the dead of the night is no fun. I bought the 4-1 right after this adventure in exhaust modification.

I love those bar end mirrors. They deliver a message for sure:-D

 

[gotjeepzj]

I've noticed the bike consuming more gas now. Anyone have an explanation for this? What's left of the baffles is now really black from carbon. I thought it should have the opposite effect. If the reduction in backpressure should've lead to a lean condition from what I've read here but that's not the case. It might just be me being paranoid, it could just be some bad gas. Thoughts?

 

[Detman101]

I've noticed the bike consuming more gas now. Anyone have an explanation for this? What's left of the baffles is now really black from carbon. I thought it should have the opposite effect. If the reduction in backpressure should've lead to a lean condition from what I've read here but that's not the case. It might just be me being paranoid, it could just be some bad gas. Thoughts?

Well, I'm guessing...Guessing...that having the can on the bike keeps some sort of balance in the engine that regulates how much the fuel can move into it. Because gas is thicker than air the backpressure keeps the fuel flowing at a slower rate. The air stays unchanged since...it's air.

So, the backpressure....in essence...keeps your fuel flow regulated by it's presence.

I realize now that I overjetted when I went up a size to run with no can on my bike. I could have left it the same and had better gas mileage.

 

[dtkid]

I gotta jump in here and ask a racing question. It actually concerns one of those vehicles with 4 wheels......the type I am rarely seen in (pretty much only when riding in the passenger seat while the wife drives and I sip beer from a quart dixie-cup.)

A buddy of mine races on the dirt-track circuit. He recently (I helped) put a huge motor (I think it was a 454) in a Camaro and I noticed that the header had little bitty (small diameter) head pipes coming from the manifold. I asked him why the pipes on the header were so small in diameter and he said that the back pressure allows for more torque.?????????????

Do ya'll know this to be true? I must admit I don't have a substantial understanding of the relationship between horsepower and torque but I know they are different parameters. CAn anyone ellaborate????

 

[gotjeepzj]

Well, I'm guessing...Guessing...that having the can on the bike keeps some sort of balance in the engine that regulates how much the fuel can move into it. Because gas is thicker than air the backpressure keeps the fuel flowing at a slower rate. The air stays unchanged since...it's air.

So, the backpressure....in essence...keeps your fuel flow regulated by it's presence.

I realize now that I overjetted when I went up a size to run with no can on my bike. I could have left it the same and had better gas mileage.

Here's my thought on this and also it's a guess. In an auto fuel is fed via a pump through a a fuel regulator which meters the correct fuel flow. On my gs it's vaccume fed. That should mean when the pistons move down the vac would draw the proper amount of fuel. Back pressure shouldn't affect the piston drawing fuel and air into the engine.

 

[dtkid]

Yes but some cam-overlap occurs. If there were no overlap and exhaust valves were completely closed during the intake phase your assumption would be correct. But I believe that all machines possess some cam-overlap and therefore the pressure waiting at the exhaust manifold would indeed affect mix delivery.

 

[gotjeepzj]

Ok but then couldn't I install some sort of valve in my fuel line and use it as a make shift regulator?

 

[dtkid]

Well perhaps in theory on some machines, but not practical or even useful on ours. (I think what you suggest is really the essence of fuel injection).

Inasmuch as our machines use gravity to move fuel to the carbs..no valve would be desirable. What you suggest is in basically what our carbs do, ie, regulate air and fuel flow.

The thing that many piddlers (like myself) forget or simply don't understand is that a machine, during operation, is sorta like a living entity. All systems and components are dependent on the operation of other components. Or, everything is connected to everything. In addition, the max. performance of all components are limited by any factor that limits the effeciency of any one component.

Consider that the shape of a megaphone exhaust, the size of the megaphone or whether the 4 header pipes converge into one or converge into two then one point absolutely affects mixture delivery during the pistons intake phase. The pipes are at least a couple of feet away from the combustion chamber yet the backwards pulse from the air expansion impinges, either in a negative or positive manner, (depending on camming) on mixture delivery and thus torque development.

HiSPL is absolutely correct about "no need for baffles/mufflers". In the days when our bikes were created guys like Yoshimura and Muzzy consistently left the silencers out of the megaphones. As a rule, I have always been taught that "as long as your exhaust pipes are long enough to keep the cooler (ambient) air from being sucked back into the exhaust manifold" the exhaust valves will be fine. I was taught that the general rule is about 12inches for a straight pipe. However, the bend in our exhaust pipes I believe allows us to shorten the header pipes even more. NOT that anyone would ever want or need to.

Well, there is a penny' worth of my input.

 

[AOD]

Cutting the baffles out or driling holes in your exhaust will NOT make the engine sound deeper. It will do the opposite, actually. The baffeling and muffler packing is what deepens the tone of the engine.

I honestly think you are going the wrong way.

~Adam

 

[scotty]

Doesnt any one read spark plugs any more. That is the first thing, before and after exhaust or carb work.

 

[dtkid]

Concerning to baffle or not..............

Whereas I live in a very secluded area of the country I don't really have to worry so much about the intense loudness of a megaphone without the baffles. In fact, I run both GS750s' without.....but is not for the sound per se, I have run my machines like this for safety. Whether it is so or not, I believe that I have a better chance of survival if the old farts where I live (nothing against old farts cause I will be one very soon) perceive a vehicle in their midst. The mountains are primarily "roaded" with many snakey and blind turns and I want folks to know that I am there.

However, I would absolutely not ride these bikes (without baffles) in a typical metro-type area. I believe that we as riders already have a negative enough image and I do what I can to improve that image. In addition, I have the baffles in the megaphone on my GS1100E. Quite truthfully, it runs better with the baffles. (I know why). And, I think the 1100 sounds better with the baffles installed. But the points concerning responsibily are well taken, we should be aware of and attempt to diminish any offensive behaviors of our riding brethren. Many non-rider types like to lump us all into one "offensive-bucket" and this new fad [yuppies dressing up like Louisville Outlaws or Hells' Angels] may seem silly to us, but it does not go unnoticed by those in our communities that percieve all bikers as offensive. Although most of us don't spend our weekends dressing up like the Village People and pretending to be tough, you can bet that we get put into the same mental category by folks that just don't understand what these machines are all about.

 

[mixongw]

I hated the sound from the meg. I purchased a 3A Racing muffler ($131) and it mated right up to the header. The sound is much better. Very low note but not loud.

http://www.3aracing.com/showroom/pro...452e7a1ce2b861

 

[gotjeepzj]

Cutting the baffles out or driling holes in your exhaust will NOT make the engine sound deeper. It will do the opposite, actually. The baffeling and muffler packing is what deepens the tone of the engine.

I honestly think you are going the wrong way.

~Adam

I cut the round plug off completely and with the last 2 staggered sections cross drilled so air can flow through the outlet cone instead of bouncing off the cone then moving backward up the muffler to the outlet it sounds nice and deeper. Not as loud or as deep as with nothing installed, but I like it. It's still quiet around town and only really growls above 3K.

 

[Rake78GS]

To baffle or not to baffle. That is the question!

To baffle or not to baffle. That is the question!

Well after reading this thread, and hearing everyones opionion. I decided to REMOVE my muffler. The entire thing from behind the 4-1 collector.

YES it is VERY loud. I expect a complaint from my land lord any time now......
And YES it DOES have a DEEPER sound to it Ever head a 5.0L Mustang with headers and a free flowing exhaust..........
Does it effect the balance of the engine? Cant say 100% because I havent checked the plugs as yet
BUT!
It DOES INCREASE fuel consumption! My fuel usage has DOUBLED on the same run as I have always done!
Does it increase HP or Torque? Cant guarantee due to lack of a Dyno tester in my living room.........
BUT the ole '78 pulls HARDER and revs FASTER than ever before.

Considering the INCREASED fuel flow, and the INCREASED rev I HAVE to assume it WOULD effect the balance of EVERYTHING else!