Muffler Repair for Honda Forman 400 ATV

[Don52]

The muffler on my customers Honda Forman 400 ATV rattled. A new muffler from Honda cost $629. (However, an aftermarket version would be less expensive). I have had good luck repairing mufflers, even though you would think the high carbon from exhaust would make it difficult to weld without cracking. First, I cut off the end of the muffler using my favorite Super Slicer Plus cut off wheel on my Matabo 6” grinder. Picture 4 shows the loose pieces that were rattling around. Picture 5 shows one of the bulkheads of the muffler with a large piece missing. If you look carefully at the bulkhead beyond this one, you can see a crack in the bottom. I did not bother to repair this one because the muffler was not too loud and it would have significantly increased the scope of the job.

1. Entire muffler
2. Cutting off end cap
3. End cap cut
4. Loose pieces in muffler
5. Broken bulkhead

[Don52]

I bead blasted the bulkhead plate to remove the rust and carbon. I sanded the ID of the can with a Scotch Brite pad soaked in Acetone. In picture 6, you can see the new piece in place that I eventually welded to the can and the existing bulkhead (sorry I do not have a picture of this weld). Picture 7 shows me welding the next bulkhead in place. Notice the orange spot on the outside of the can of the muffler indicating good heat penetration. Picture 8 shows the washer that I welded to the bladed bulkhead. I added a washer because the outside of the bulkhead was thin but the center was solid. I wire brushed the bulkhead and cleaned it with Acetone, but in hindsight I should have bead blasted the vanes of this bulkhead to better clean it up. As you can see, the weld has some contamination in it. The weld in picture 9 that attached the washer to the ID of the can went better because it was cleaner. The last picture, #10 shows the weld to attach the end cap to the end of the muffler.

1. New bulkhead installed
2. Welding new bulkhead
3. Washer Added
4. Washer welded to muffler
5. End cap welded back on

-Don

[MAC702]

Productive project and a nice pictorial!

[Don52]

Productive project and a nice pictorial!

Thanks, I appreciate your comment.

-Don

[Noel]

I second it, job well done. If you posted for inspiring others, you did and almost made it look too easy.
Lol... maybe It was for you? But still a bit of work. Good on you for repairing it.

With your tutorial of explanation and pictures, " I " thank you.
I'm sure others as well. Some one some where is going use it to justify buying a "Mig" welder for the garage.

From those about to weld, we salute you!

[FusionKing]

Great thread. At least some people (us) will be able to view all the hidden craftsmanship in that project. Thanks for sharing... I love all your projects!!
How did it sound??

[topgunner]

Awesome project! Wondering how it sounds.

[Don52]

Great thread. At least some people (us) will be able to view all the hidden craftsmanship in that project. Thanks for sharing... I love all your projects!!
How did it sound??

Nice and quiet.

-Don

[Taw Paw]

I like it!!!!
Awesome work.