Still very new... Got questions about mufflers.

So I've been looking at new mufflers but am unsure as to what each muffler does... sort of.

I was looking at a 4 to 1 and 4 to 2 and was unsure exactly what the difference is between the two. I was also wondering how easy it is to take off and replace a muffler?

 

4-into-One and 4-into-2 describe whole exhaust system configurations; mufflers are just the thing(s) that go on the end. A 4-1 exhaust system means that it has 4 head pipes that join into one pipe that a single muffler attaches to. A 4-2 system means that the four headpipes join as pairs and exit via TWO pipes, each with its own muffler. The XJs that use a "collector box" system are technically what is known as a 4-1-2 system. That's because the four pipes join into one (the collector box) and split back into two pipes, each with a muffler on the end. When you see a listing, for instance, for a MAC 4-1, it generally means the entire system, including a muffler, or pair of mufflers in the case of a 4-2.

On your bike, if it has a stock exhaust system, it's not so easy, but not horribly difficult. Each muffler is welded to the "pair" of pipes for the side it's on. You'd need to cut them off, leaving enough pipe to clamp a replacement to. Then you can clamp on your choice of "slip on" replacement mufflers.

Individual replacement mufflers are referred to in the industry as "slip ons."

Your bike (again, assuming stock) has a "pair" of 2-1's with a crossover pipe. Each pair of pipes (#1 & #2; and #3 & #4) join into a common pipe that the muffler is welded to. Those two "common pipes" are joined underneath by a crossover pipe. So your system is actually a 4-2-2.

Confused? Look at your bike's exhaust in the fiche; then look at the exhaust listing for the 650 Seca or the 750s, which have the collector box.

 

Also check out the jc Whitney muffler posts in the mod forum for some cheap slip on options.

 

Well after reading bigfitz post I went out to check my muffler, which is not stock, and I'm not sure its properly on. But I can see the welds are not welded completely or at least weren't done efficiently.

So that, plus getting my carbs cleaned will be my next project...

Which should I do first? Clean carbs or new muffler?

 

Bobby does your bike run poorly bad mileage idle rough?

 

Mileage isn't THAT bad, but not what I expected, but yeah it does idle pretty rough.

Also, I'm not sure if this was clear in my initial question, but what does a 4-1 do that a 4-2 doesn't or vice versa?

 

In my opinion NOTHING it's just a matter of looks. If I had my way I'd trade my 4to1's for stock. My XJ750 came with 4to1's on it.

 

In theory, 4-1 should provide some improvement in power IF combined with correct jetting. It will also change the sound and generally be louder.

The reasoning for the power improvement is that four cylinders exhausting into one pipe, with the correct header lengths, is supposed to give a more continuous flow - i.e. the velocity of gas exiting out from previous cylinders pulls the gas out of the currently exhausting cylinder.

The reasoning for the jetting change, is that carburetors don't have much flexibility in fuel metering at a particular engine speed. Changing much of anything about how freely an engine breathes in or out will usually mean that jets, jet needles, and pilot screws will need to be adjusted or replaced.

 

4-1 feeds half as many mufflers. ya just carved off 15lbs easy. The 4-1 header itself is generally lighter too. Not that we XJers have any right to be concerned with grams and ounces of unsprung weight or anything... and what SQL said.

For ratters like me piecing together rotten bikes headed for the heap, aftermarket entire headers are generally significantly cheaper in the 4-1 variety. Very little if any manufacturing change is needed to adapt them from one bike to another so economy of scale kicks in. 4-2 and such with their cross overs and collectors need to be made just so in order to fit a given model and often aren't even all that available.

If your headers are good then I'd say that nothing I have to comment on the matter really has any bearing.

 

Bobby your one of the luckier ones if you have a bike that cranks and you can ride, most newbies come here with bikes that wont even backfire. I would not mess with the carbs till I did some other things first . Before you even mess with anything do a compression test and record the numbers just so you have a baseline. Next thing you will want to do is adjust your valves its an easy job but it looks daunting in the manual really its one of the easiest jobs to do once you get started and if you pull all the shims the first time and record the sizes it will make the next time even faster. Then do another compression test and record the numbers. Then you can evaluate the carbs.

 

thanks for catching that Waldo.

He speaks the truth.
-Adjust valves.
-Clean carbs and/or confirm they're clean (pass clunk test and flow cleaner through all passages)
-Seal vacuum and exhaust leaks - futz with intake/exhaust mods.
-Adjust / tune carbs

in that order or else you'll be chasing your tail all over.

 

Back to the mufflers:

I just looked at your pics.

Somebody has already cut the original mufflers off and replaced them with slash-cut slip-ons. MOUNTED BACKWARDS. YOU HAVE THE LEFT ON THE RIGHT AND VICE-VERSA.

I suspect the PO couldn't get them to fit so he flipped them around; all you need to do is remove those mufflers and install them on the correct sides. You may need to fabricate a way to slightly lengthen the brackets, which like I said is probably why the IDIOT installed them backwards.

That's about one of the silliest things I've seen done by a PO yet.

 

Ha! He did a lot of DUMB things to my bike!
He intalled the wrong spark plugs.
He painted the tank twice, while still attached to the frame, so in places I have speckles of sparkly blue paint on the engine and other its orange?
He had attached the wrong throttle cable, incorrectly.
And those are the things I found on my own...
Someone told me the muffler was backwards, but after getting a 2nd opinion, I was told that they weren't neccessarily, so I'm glad you noticed also... cause it does look weird to me.

But I digress, she's mine now, and I'm gonna do her right. BOBBER!

 

Fix the mufflers and get it running right before you start cutting.

 

Ha! He did a lot of DUMB things to my bike!
He intalled the wrong spark plugs.
He painted the tank twice, while still attached to the frame, so in places I have speckles of sparkly blue paint on the engine and other its orange?
He had attached the wrong throttle cable, incorrectly.
And those are the things I found on my own...
Someone told me the muffler was backwards, but after getting a 2nd opinion, I was told that they weren't neccessarily, so I'm glad you noticed also... cause it does look weird to me.

But I digress, she's mine now, and I'm gonna do her right. BOBBER!

 

previous owners will corn hole ya every chance they get. I think I had occasion to say that three of four times today alone.
Heck I just tossed some plastic bits across the garage, not a PO...
Went to a bike shop which admittedly I KNOW has a bad rep for service but I go there to buy what I need and GTFO. Asked for some spark plug caps. Told the guy bike year blah blah. I also told him what the resistance rating was supposed to be on each. (two are 10k ohm, two are 5k) and he goes "yeah yeah there's two different ones, here ya go, these are the OEM listed ones" and hands me a pair of one little box and a pair of another little box. "okay" pay and go.

Just got around to putting 'em on and sure 'nuff. two sizes but all 5k ohm.

Trust no-one but yourself with your bike. and double or triple check your own work to boot.

Sorry for the off topic ramble.

 

OK,I stopped laughing,Fitz is right,mufflers on backwards.