1st post, with a lot to learn....

When removing bafflers... do you have to adjust your carburetors air / gas mixture for proper engine use?
With no bafflers in your pipes do you lose power in high or low end, or gain power in low or high end?
How about when adding a wider tire?

 

Generally speaking, no mixture adjustment is required.
Removing the baffles will cause a loss of torque in the low-mid range. Since that's where you spend most of your time if your riding on the street, it's not the brightest of ideas, unless loud is more important than performance.

Wider tire? Since you don't list what bike you have, or what you have in mind, No Comment.

 

Thanks. I am on a 2000 Sportster 1200 XL C. I will be upgrading my present stock rear end to a new 250 set up.

 

He must not be worried about performance. I bought mine with no baffles. The dude I bought it from loved it that way. I wont lie, at first I did to. But after a week or so I had had enough. I bough some baffles from my local indie. I could for sure tell a difference. I took them back out and drilled the holes out a little more and it gave it a little more sound. They are not my first choice of exhaust but also not my first on my to do list. No baffles is not that great.

 

Razorback Rob, Thanks for your reply. Did you feel a difference in performance? How noticeable was that for you and would that change your influence over sound? Thanks. A

 

if you remove the baffles doesn't that kind of make the pipes straight? (or straight through?) and if this is so, couldn't an increased air intake make it run well? not trying to hijack the post, but i thought one of the few things i understood was the relationship between intake and pipes....

 

Adding the high flow a/c would indeed alow it to flow more air, but straight pipes with no baffles are called "drag pipes" for a reason. They are good for wide open throtle high rpm runs down the drag strip. Straight drag pipes do not allow for proper scavenging of the exhaust which kills low end power and torque. Technically an adjustment of your fuel trims would also be needed because the improper scavenging will actually push exhaust gas back into the exhaust valve and cause a lean condition if you are running short pipes like most sportster owners do.

 

Actually, reversion has two aspects. One is pushing a little burnt gas back into the cylinder. But that's a minor aspect of the pressure wave. The big thing is that the sonic shock wave often doesn't stop in the cylinder. During the valve overlap period, that shock wave goes in the exhaust valve, through the cylinder and back out the intake valve, back out the intake manifold and clear back out of the air intake. On a carbureted engine, the next intake stroke sucks back in that air/fuel mixture, and the carburetor being a stupid mixing valve, takes that incoming fuel/air mixture and efficiently mixes in another dose of fuel. The intake charge reaching the cylinder now has a double dose of gasoline, all of which cannot possibly be burned with the oxygen available in the cylinder. It is like running one cylinder on full choke. All that gas has to go somewhere. Some of it condenses on the cylinder walls, and the rings scour the cylinder gas-coated walls and you have cylinder wash-down and completely unseated rings in that cylinder in short order. That's just a start. Then the gas gets down into the oil and contaminates the oil, and starts washing down the other cylinder. The thinned out gas now leaks past the unseated rings and oil consumption goes up. Increased blow-by past the unseated rings produces higher crankcase pressures, and the engine starts spitting the thinned oil out of the breather tubes, and black stinky oil starts dripping from the air cleaner. Are we having fun yet? The super rich mixture in (usually) one cylinder often repeatedly fouls the spark plug. Gas mileage goes further down. The oil being spit into the air filter, coupled with the reversion shock waves inside the air cleaner, saturates the dry filter element with oil from the inside out, clogs up the filter element, decreasing air flow and further increasing the already rich running engine.

Not one good thing comes from running a Harley with reversion.

If you've pulled your baffles or have some straight shooter whodunits, you might want to remove your air cleaner and gently rev the engine a few times. If you see a cloud of fuel being puffed out of the throat of your carburetor or air intake, well, welcome to the wonderful world of exhaust reversion. Take a sniff of your oil. If it smells like its full of gas, it probably is. Just imagine what that thinned out contaminated oil is doing to the crankshaft roller bearings. Nothing to smile about. The bearings don't like it either, which they'll make you aware of in about 10 thousand miles if you keep running it that way.

Once you get rid of reversion and change the oil filter and put in fresh, clean oil, and thoroughly clean your air filter, it takes right at 400 miles of moderate riding to get the rings re-seated again.

The good news is that if you catch it and act on it in time, you can have an engine that runs clean again, doesn't spit oil into the air cleaner, and consumes maybe a pint of oil between 5,000 mile oil changes. I know this from experience born of stupidity and pig-headedness. But my 96 883 now does not spit, drip, contaminate or consume oil, it no longer fouls the rear plug, the oil smells like oil, and the air filter no doesn't smell like an old gas rag.

Same carb, same jets, same everything including the original 1996 air filter, except I made some changes to the exhaust system to get rid of reversion. Those changes were made 10,000 miles ago, and the engine runs stronger than it ever did, and without puking or consuming oil.

Just my 2 cents. FWIW.

 

You will notice a significant difference in mid-range torque without the baffles. I once rode a bike that was identical to mine, as far as engine, air cleaner, etc. The only difference was I had Cycle Shack Mufflers, which have small baffles, and the other bike was running drag pipes (straight).

His bike didn't really sound any louder than mine, and the performance of my bike was far better. The real kick in his pants what that he had paid about $100 more for those drag pipes, than I paid for the Cycle Shack Slipons.

 

ugh,
In order to actually have drag pipes effective for low end torque and such, Your going to need to add a few internal goodies to make some extra air flow out.