1980 CB750k Delkevic Exhaust

Piczker08

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Hey all,

Back early in the summer I bought the Delkevic Megaphone Exhaust for my 1980 cb750k. Link below.
(http://www.delkevic.us/index.php?ro...r+and+Stainless+Steel+4-1+Headers&SKU=COM270V)

I rode through the whole summer and absolutely love the exhaust, except that its a tad bit tooo loud. Now that winters upon us I figured i'd try to get around to silencing it a bit. I contacted Delkevic to see if they sell any silencers but they do not, unfortunately.

Does anyone know any effective and safe ways that I could silence the exhaust a bit more.

Any advice appreciated,
Thanks! :D
 

amc49

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You could try to make up a baffle tube that goes into the front section just before the rear cone if you have any skills for that.

The problem there is that the rear cone is too short and the bigger angled baffle takes up too much space inside it. The outside cone has about half as much internal area outside the baffle as a normal longer cone does and airspace outside the flow path is what you need to kill noise. Adding more packing helps kill noise until you then close up all the sound absorbing spaces in the packing, then the more solid it gets the more noise it does NOT soak up.

Incidentally, one can go to any Home Depot and pick up a 'project insulation' package of regular old Pink Panther Owens-Corning pink colored house wall/attic insulation and have enough insulation to do several pipes for far less money, simply stuff or wrap the baffle with that and masking tape to hold the pack in place until inside pipe and it works like gangbusters. I've used it for years. The commonly sold reload packs the bike places sell are highly overpriced.

The insulation is all pretty much the same, the degree of tightness you pack with has more to do with how much sound gets killed. More insulation is better until you begin to pack too tight then the sound comes back similar to oil soaked packing which gets louder again. The sound deadening small airspaces are clogged up and then don't work.
 

Carbs4Life

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I have this same exhaust on my '81 CB750C. I took it apart and found the outer baffle was packed pretty tight. Maybe a little looser pack will have better effect. Has anyone been successful quieting this exhaust?
 
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