Bird Brains – Generator Exhaust Stack Kit (This set up will work on 87-89FC35 w/Onan - may need slight modifications for other FC’s) Since I made up this unit - I modified it by adding a second 90 degree elbow so the stack would clear the rear awning. The below instructions includes this change.
I purchased the below items from Home Depot in the electrical & plumbing departments & I bought 2 – 1.5” inside diameter 90 degree exhaust elbow pieces from Pep Boys


1 ea 10’ section of white PVC or electrical PVC conduit 1.25 dia. (Inside Diameter)

2 each 1.25 dia., conduit screw connection joints (grey color in the electrical department of HD) (each connection consist of 2 pieces - threaded joints 1 male & 1 female)

1 each 3” 1.25 dia., straight line conduit connector (non-threaded)

1 each 1.25 dia., white “T” joint - white PVC (plumbing department)

2 each 1.25 dia., 90 degree elbow connectors (plumbing department)

I took the 10’ section and cut it into 3 equal sections of 40”.

1. I first glued the 2 threaded screw connection on one piece of 40” PVC so I could screw either of the other two sections to make it fool proof. I glued it with the 2 female ends, one on each end of a 40” PVC section.

2. Next I glued a 3” straight connection joint to one end of the second 40” section and the male end of the screw joint to the other end.

3. On my third piece of 40” I first glued the male section of the screw joint to one end.

4. I took one 1.5” ID – 90 degree elbow and shoved it onto my generator exhaust pipe and ran it parallel to ground & I stuck a 2nd elbow to that one pointing up. This set up will set about 7” from the skin on my bus (88FC35 8KW Onan). (With this configuration I did use a #12 x ¾” self tapping screw for the 1st elbow, to hold it up and it can stay while in this position while traveling)


5. I screwed the three sections together with the straight joint end sitting on top of the elbowed exhaust section.

6. I climbed to the top of the bus to see how high I wanted the exhaust to protrude above the bus line. I finally cut that section to be about 30”. I then set NOT GLUED the “T” section to this piece and glued the 2 - 90 degree 1.25 elbow joints to the “T” section at about a 30 degree downward angle. (This would prevent any rain going down the exhaust stack.) (Once you get it all glued up there is only one way for it to work on the exhaust elbow so you can’t screw it up)

7. I painted the whole thing with the grey primer because I used both white & grey PVC pieces. (Final color to your choice)

8. I took a 1/8” thick x 1” wide aluminum strap and fabricated the top bracket which connects to the goat rail in the left rear corner by 2 - 9” ball bungies. The bracket is held together by 4 - 5/16” x ¾ bolts. The distance from the corner of the goat rail to pipe connection point was approximately 16” which puts the stack about 7” off the skin of the bus.

Total build time about 1 hour or less. It actually took me longer to find my pipe cutter then it did to fabricate this setup.

Tools needed: 2” pipe cutter & hack saw, electric drill, 5/16 bit, ½” wrench, medium/fine grit sand paper, & a can of PVC cement.

Total cost: Under $20.00 before the bracket but around $27.00 with the top rail mounting bracket

After about 4.5 hours of run time on the generator the bottom section did slightly warp but it never collapsed. If I were to run the generator or dry camp for several days I think I would want either aluminum tubing of light weight steel tubing for a solid or more rigid stack .

Bird Brains 88FC35 John - Louisville, KY/Jeffersonville, IN 812-282-7253