How to quiet down my '76 KZ400

Ok so unsurprisingly I was wrong. It's not all one piece, I just couldn't see the bolts from the angle I was standing to take the last set of photos. There's bolts for it to mount to the bike and what looks like a set of holes to work like a clamp but at least the left side was missing a bolt there so I was able to just slide it off. Not seeing a way to take out the baffle to repack it, but is there some type of spray foam type of thing I could shoot in there to work in place of the fiberglass material?

I think the answer is in your second picture.

See the threaded portion which sticks out about an inch? (I'm guessing that's for the rear mount.) Look about four inches away from that toward the muffler exit - I'll bet a shiny nickel that if you remove that other bolt the baffle will come out.

The spray foam idea won't work, unfortunately. The muffler will get too hot and the foam wouldn't really dampen any of the sound. Fiberglas reduces the sound because it is sort of open and porous.

Should have added that I had the same thought, took that bolt out and didn't seem to let the baffle budge at all but I wasn't really able to get more than a finger in there to try to wiggle it. If you think that's a real possibility I guess I'll take it back off tomorrow and see about finding something that I can get in there with to try to get it free.

Baffles can be very sticky to remove.  They seldom get any attention, so when they do they are often rusted and covered with carbon.  I agree with Nerdy.  Take some time to loosen them up first.

KZ400 muffler baffle tube. not sure if this is something you could use. might be kind of pricy, though. ~$65T on eebbaayy.


Here's one from Niche cycle but probably isn't available. the pic is more than a few years old.

ThatYeti wrote:

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

You can buy Emgo cans that will clamp on to the end of the header. They come with spacers you can use to take up the difference between the header and the can. 
Z1 Emgo muffler

Ok, so a little more wiggling and I was able to get the baffle out no problem. Definitely had insulation at one point...but not much left anymore. Will order some more and see how much adding that helps.

ThatYeti wrote:

Ok, so a little more wiggling and I was able to get the baffle out no problem. Definitely had insulation at one point...but not much left anymore. Will order some more and see how much adding that helps.
 

Woohoo! Yeah, that's pretty close to an open exhaust at this point; the new fiberglass will make a big difference.

You can actually adjust the coverage and thickness of the fiberglass to achieve the sound level you want. When I was a kid I had a bike with a baffle like that, and just for grins I took an old t-shirt and wrapped the whole thing on there tightly - it barely fit back in the pipe. The bike was very, very quiet but didn't run especially well.

Ya thinking about it all day I figured it had to come out and was pretty happy when it did. Ordered some of the stuff below and hoping I can just reuse the wire as I wasn't able to find more of it. Planning to pack it as tight as possible as I'd like it to be about half as loud as it is, but at what point do I start affecting the way it runs?

Ceramic Muffler Packing Exhaust Muffler Packing Kits Universal Muffler Repacking Mat for 2-Stroke 4-Stroke Motorcycle ATV Dirtbike Exhaust Spark Arrestor a.co/d/gpI5NgL

It's been a long time since I did one, but IIRC you don't want the sound deadening material to be packed down really hard: wrap it snugly but don't crush it. You'll probably want to confirm that, though.

Also before you remove the old wire, see if you can determine how thickly the baffle was wrapped when it was new. You can use that as a guide for your first wrap.

Agreed with Nerdy, you don't want to pack it tight.  The idea is just to fill the space around the perforated tube with packing, but the exhaust will still "flow" into the packing.  If you pack it tight you will effectively turn it into a small id solid tube which won't do much sound deadening.  You can use any thin wire you want, all it does is hold the packing in place as you're assembling the muffler.

Thanks and ya I'd watched a couple 'how-to' vids and seems some people don't bother with the wire, just using masking tape and letting it burn off, but it holds the material in place while you're installing it back in place.  Will try to just re-use the wire that's there but worst case I guess I'll go the tape route.