Dueling Kz400's

Here's the pile of pipes. Two factory headers (with extensions already welded on). Two crappy headers that came with the bike. And the aforementioned U-Haul table leg. We also used some conduit scraps from work that we salvaged, but they are not in the photo.



I took a bunch of measurement photos for reference.

We ended up cutting everything with a hacksaw and shaping with hand files. Yes we have power tools but there is a bit of zen peace you get from cutting and shaping by hand when it comes out just right. I may have used a grinder here and there for quick touch-ups but almost everything was done by hand.

These washers were cut down and filed to be the endcaps of the mufflers.






This was a test fit onto a sample of conduit for the inner baffle.

Here are some more extension pipes, inner-baffle conduit with holes, and the table leg cut in half to make the cannisters.


Welding fixtures.





The table leg had some thin-rusty spots that would blow out with the welder, so I had to build up blobs to put some metal there.

I'm using a flux-core, wire-feed, that I don't know how to use, so don't expect anything pretty.

End caps tacked.




Things have to be done in the right order. Once it's welded, it's never coming apart. so don't screw up!
Remember this is only to square up the inlet cap... don't weld it to the cannister yet!

We didn't have any muffler packing, but we had a ton of that terrible fiberglass muffler wrap. I figured we should put something in the cannisters to reduce resonance, so I loosely used some wrap around the baffle pipe. The fiberglass dust got on everything. Ugghh. Not fun stuff.





I used a long threaded rod and spacers and nuts to hold the cannisters together for welding. We shaped the endcaps with a chamfer so the tension on the rod would naturally form the cannister-wall into a seal when it was pulled tight.

Because the metal was prone to blow-through, I assembled everything with tack welds instead of beads. It gives it that rustic look.




The outlets don't need to really be sealed air-tight since I expect the entire back end to get covered in soot eventually anyway.




There will be more tacks to seal up the inlet.


We will use these extensions later to bridge between the headers and mufflers.

The hangers are scraps from the dumpster again. They will be hanging off the passenger pegs. They are little overkill, so I'm not sure how permanent they are. We just need something to work for now.

Some test fitting.







We had to precisely grind the connection pipes between the headers and mufflers to get everything to hopefully match on the left and right sides. That took some time.

My buddy did some the of the welding on the connector pipes. He has a tig setup while I was using my flux-core. So there are some differences in the welds. Sometimes the tig was better and sometimes the mig was better.




When two people are in a rush, it really multiplies the chances for errors. We did most of the work in little bits of time just before going to work. So there was always a hard deadline. Racing the clock does not make for great quality work, but we're both so busy it was the only way we could do it. I was glad to have him take some of the welding load. He was already on another deadline to get the U-Haul camper done before he and his wife went on a two-week road trip.

One snafu was due to a miscommunication. of what areas were ground (to remove zinc plating etc.).


We lucked out in that most of the botched areas were in areas that were going to be out of sight.

And it's done.





Hobart Handler 140.


We did already have new studs and gaskets as part of the budget. We knew we would need those earlier.


Here's the leftovers.

So I don't have a great photo of the exhaust yet, only this one.

Notice there is a little blemish on the tank. That was not there when we bought the bike. That is a harbinger of the sorrow to come.



In the mean time, you can give a little listen to how it sounds at idle with a couple rough revs.

Are you happy with how it sounds?
I'm planning on making a similar exhaust for my scrambled Z400, but going for a high level stainless steel system with both pipes on the same side.
I'm going to use 1.5" going into 2" muffler packed with exhaust wadding, so I should think the sound level will be about the same as yours.