Cracked exhaust

[Ivan]

I have a Mac 4 to 1 (I think, it was on the bike when I got it) and it is cracked at the rear mount. Since the PO was gracious enough to gut the muffler portion, I was thinking of cutting the tube off and doing away with the megaphone style and getting something more stylish. Would an automotive "Cherry Bomb" type muffler work ok? I have seen them nicely chromed, and could probably find one that would slip on the exhaust tube. Might even be quieter.

[TopCatGr58]

IF straight pipes will work on these things, the cherry bomb on the end of your 4-1 collector should also work! My Mac megaphone is a simple center louvered baffle, essentially an expansion chamber, and I've drilled holes in the end plate to allow more "TONE" anyways.

The Cherry bombs are lined with fiberglass, the muffler section expands but then narrows again at the end. It seems to act like a pistol silencer absorbing "some" of the exhaust vibrations, without being very restrictive.

The stock harley mufflers folks put on their stock pairs of 2-1 pipes does essentially the same thing, just in smaller scale.

Take lots of photos, and a video with sound for us!!
T.C.

[Ivan]

Been looking at it, and I think a Cherry Bomb #87408 will work, I'll just have to pull the exhaust at the header. Probably use a flat band clamp, and maybe a nice tip on the end. Not sure. I'll see if Autozone has them tomorrow.

Anyone have a definite answer on what size the pipe is? I tried measuring around it and come up with a 2 1/8" outside diameter, so I am assuming it is a 2" exhaust.

[Ivan]

Well, I finally got it done. almost.

I used a 87048 cherry bomb glass pack. It is a slip on for a 2" exhaust. Ironically, the header is also that size. Just a tad bigger. It was an odd ball size and I couldn't figure anything to make it work, so I took the header and the muffler to Midas and asked them to swell the muffler to fit over the exhaust. Thankfully they swelled the header instead, so if I ever need to go back, I can't.

I tried a 2" and a 2.5" easy seal clamp and neither one worked, no place in town has 2.25" clamps. I finally cabbaged the 2" enough that it kinda works.

Any way, the sound is like a sport bike. The glass pack is surprisingly good at muffling the sound, and although there is snow flying here today, I can tell that the bike responds to throttle much quicker than with the Mac muffler on it. It really does sound neat. I don't have decent recording equipment, but it sounds a lot like the video of the XSs with the Yoshimura exhaust.

Last thing I need to figure out is a way to mount the muffler to the rear of the frame somehow so it isn't just hanging off the header.

When I get it all finalized I will see if I can find someone with a video cam and post it up on youtube.

[trbig]

They make a coupler to join 2" pipe.. sorry to hear he stretched out the header pipe.

Last dealings with cherry bombs was when I was a teen, but I remember them being made from a pretty stout steel. Seems you could weld whatever type of ear you needed to the outside of it without having to worry about burning through the muffler.

Are you leaving them red?

Tod

[Ivan]

Yeah, its a pretty close match to my tank, so I will leave it red.

I think this muffler is made from 1/8 sheet. Pretty stout. I have a buddy that can tig an aluminum can back together, so I can get something welded if I need. I was thinking of just making a hanger that would serve dual purpose as a clamp to hold on a nifty tip instead of just the end of the muffler out there. Although, it doesn't look too bad the way it is.

The 87048 is a 21" overall length, with an 11º degree offset in both ends. It tucks in nicely. It is close to the tire when it is all mounted up, but that is at full suspension travel. With my fat butt on there, it will be ok.

Pics to come...

[Ivan]

Where is a good place to put audio files so I can link to them?

[Ivan]

Well I cobbled together an exhaust hanger and let it rip today for an hour or so. The straight through muffler definitely has a better sound on the road, probably even quieter. Doesn't sound like a tin can.

The top end was noticeably more powerful. It pulled hard to redline. Much more so than with the Mac can on it. The low and mid ranges didn't seem to change at all. First gear redlines at about 50 with the 750 FD, hard to tell, it don't take long. Second redlines about 80, and third was above the century mark and still pulling. I hit fourth at 110 indicated (probably about 105 actual) and still pulled hard. Fifth was too much for a fat guy with a coat that acted more like a parachute than insulation and she wouldn't pull anymore. Out of fairness to fifth, I was only pulling about 5500, so I may have been below the HP curve.

Probably will need to work on main jetting again come spring time. It sounds kinda soggy on the top, and I get a good puff of black smoke when I goose the throttle.

[bikerphil]

exhaust mod

The top end was noticeably more powerful. It pulled hard to redline. Much more so than with the Mac can on it.

I'm running a Mac on one of my bikes and I'm interested in your glasspak mod. Got any pics?

[Ivan]

I will snap some soon. It looks kind of horked up, since I couldn't find a good way to hang the back end of the muffler on short notice, so I used some autozone stuff. it was too nice to not ride yesterday.

I will try to get some pics today.

[trbig]

so I used some autozone stuff

Ahhhh... the ol' bailing wire, duct tape, and zip ties method. Now you're talking my mechanical abilities!

[Ivan]

Pics and some video of the sound. My camera didn't record very well, so the sound just isn't done justice.

My exhaust album

[trbig]

Ivan...

Sounds OK... But man, I gotta be honest. That's the ugliest thing I've ever seen on an 11. Well.. besides Prometheus.

[Ivan]

You talkin about me or the muffler?

Either way, $50 can only get you so much in the looks department.

[trbig]

$50 can only get you so much in the looks department.

Ummm.. Not touchin' that one... lol.