How to quiet down my '76 KZ400

Not sure exactly what exhaust is on it but I'd assumed it was factory, save for how loud it is. Not looking for whisper quiet but something a little more tame wouldn't be bad.

Is it possible to bolt in some kind of baffle? Or add some fiberglass insulation? Or do I need to cut and weld in a different muffler entirely?

Thanks in advance 

 

Those aren't the factory mufflers, must be aftermarket.  Maybe one of the other members can identify them.

Seemed to be one piece up to the engine so I figured they must be stock but I guess not.

If the baffles are removable, there should be a bolt or screw head near the open end, on the side toward the motorcycle, where we cannot see in the pictures. If they exist, it may be possible to remove the baffles and replace the packing. It will likely take a lot of good penetrating oil like Kroil or Liquid Wrench and a good bit of heat and patience.
If you get them out, I suggest not using ordinary house insulation. Get proper muffler packing.

Otherwise, plugging up some or all of the oval openings may reduce the sound a bit.

i took the "baffles"  more like a series of pipes in a secondary chamber and replaced it with a baffle i bought off of ebay.
I wrapped it in fiberglass and screwed it to the exhaust pipe.
Not too bad but taking out the stock baffle was a pain as it's spot welded in place.

Just do an ebay search for "exhaust baffle"
 

Appreciate that, but is there a way to get the old one out that I'm not seeing? Don't appear to be any bolts of fasteners of any kind that I can see.

Not sure how much you want to spend, but you could try these:

MAC 1 1/2" Chrome Slip On Kick Up Taper Tip Mufflers Fits: Kawasaki 74-77 KZ400
https://www. [ebay].com/itm/361706080721

If you cut off the bell-end mufflers you should have a header pipe with an outer diameter of 1.5" - best to measure that, though.

As already mentioned, there should be screws holding the baffles in.  Look near the end of the exhaust on the side closest to the rear tire.  If there is no screw then I'm afraid you are screwed!  But if you're looking for an improvement you could always spend some time cleaning those engine cases.

Thanks will double check but didn't see any screws before and plan to clean up the engine cases but don't think that'll really help in quieting it down at all

Ok, but if I cut off what's there do these replacements need to be welded in their place?

My baffles had to be cut out.. Kawasaki welded the things in there, but I had a KZ440.

stock KZ440 baffle design 

ThatYeti wrote:

Ok, but if I cut off what's there do these replacements need to be welded in their place?
 

No - you can go to an auto parts store and get a couple of muffler clamps that fit a 1.5" pipe. Be sure the mufflers you buy have an inner diameter of 1.5". This will allow the existing header to fit into the inlet of the muffler, then you can apply the clamp to hold the two pieces together.

I recommend you look for stainless clamps; they are available on Amazon and likely elsewhere. Regular automotive clamps will probably be made of mild steel, which means they will rust.