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Discussion Starter #1
Hey Guys!

I hope everyone had an awesome Thanksgiving! I recently bought a 73 cb 450 (my first bike). I noticed that there are some smoke coming out of where the header and exhaust connects. Any help would be greatly appreciated! Also here's a photo of my bike! Thanks! IMG_1396.PNG IMG_1326.JPG
 

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There is (was?) a packing that slips over the outside of the header, and the slotted end of the muffler is squeezed to press against it, to make the seal. Age and flexing of the joint will allow the slots in the front of the muffler to begin leaking under the clamp. It is a royal PITA to get a good, durable seal there, but not impossible. I certainly exercised my vocabulary getting mine to seal.
 

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My SL smoked quite a bit after I dropped in the new rings,but quieted that mess down after a few running hours on them. I also know I probably need to track down the copper (I think) manifold exhaust shim gaskets, as well and I am still I.S.O. an oem type muffler.
I have debated switching it over to CL or CB head pipe and all for obvious reasons.
 

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the underside of your bike looks like its wet with oil...could be at least some of that smoke is from oil burning off and will disappear once the oil has all been cooked off. (assuming there isn't a persistent leak)
 

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I took apart the smoking header to check and yes it might be the seal where the header and muffler meets but also I saw that the metal ring that goes around the header and engine connection is split. Would this cause the engine to sputter as well when the throttle is rolled? Whenever I roll the throttle the engine sputters and the smoke intensifies. I'm thinking of getting new mufflers as well. Would this work with my cb 450? Thanks! 80-03310-vintage-cafe-racer-caferacer-bobber-brat-chopper-custom-motorcycle-exhaust-parts-12-inc.jpg
 

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OK, do you mean the 'ring' that pressed the header into the recess in the head? If so, that's how it is supposed to work. But, if the seal behind the header flange needs replacing, then, yes, that seal leaking can cause all sorts of problems.

I have similar mufflers to that slip-on; you'll find that they are crazy loud, as they are basically open tubes, with a little packing around the inside. I made plugs from gas pipe caps and three 5mm set screws to reduce the exit area, thus the volume. One more thing, that bar on the side, which is supposed to support its weight, is probably too short to reach a hard point (the passenger pegs). I had to extend them with another pair.
 

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Yes, the ring that goes around almost in the inside and around the header is split into two, not the flower looking ring that goes outside. haha

What would you recommend for a straight on short mufflers for a cb 450? Thanks!
 

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As I said, I have 'mufflers' that are very similar to what you've pictured; I just added 'lollipop' plugs to the back end to quiet them down, and give a bit of back pressure. I like them fine, now; louder than stock pipes were, but not ear-blasting. Once I had the mounts taken care of, they are solid, too.
These are early examples of the plugs; the smaller the center hole, and less grinding the flat areas, the smaller the exit area. If the area is roughly equal to the exit of the stock pipes, the volume is about the same, so you can tailor them to your preferences, if the caps start out large enough. Also, I went with headless set screws in the later versions of these; they are tightened with an Allen wrench that I ground down to fit.
 
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