Monday, November 2, 2009

Exhaust and Tires

Saturday it was time to install the new exhaust. Since one of my pipes had broken-off I have one bad and one good OEM muffler. Since I haven't found another header I decided to see if I could remove the good muffler and salvage and both headers for potential re-use if we ever want to go back to stock.

With the header pipe and a destroyed muffler to use as a test dummy, I pulled the bad exhaust off the bike. I found you could rotate muffler on the header pipe which meant the muffler was not welded onto the header. The only thing holding the two pieces together was a steel ring that was pressed on to create the seal. With my vice grips and bench grinder I was able to chew through the ring and the two pieces simply slipped apart!

I decided to create my own slip on system so everything could be taken back apart. My system consisted of a 6" length of 1-1/2 diameter exhaust tube purchased at Pep Boys, a couple of pan-head screws and some Exhaust System Joint and Crack Sealant. The 1-1/2 tubing was a nice tight slip fit right over the header. I left the flange on the header applied a liberal amount of sealer and just butt fit the two pieces together. I drilled a 1/8" hole and locked the two pieces together with a sheet metal screw. The sealer forms a "weld-like" bond but it is one that can be cracked apart for disassembly.

The mufflers have an 1-1/2-ish intake. This is not a slip fit, my guess is its 1-5/8" or some crazy metric size. So I made a run down to Autozone to "borrow" an exhaust spreader. (Autozone allows you to borrow tools, just leave a deposit and bring it back within 5 days.) The plan was to expand the exhaust tube to get a good tight slip fit. The problem was the 1-1/2" expander wouldn't fit into the 1-1/2" exhaust tube they were the same diameter. I would need a smaller size expanded which they didn't have at Autozone.

I decided to go the other direction. I pulled out my Saws-all and cut two cross cuts the width of the blade into the new mufflers. These cross cuts allowed me to reduce the opening to a tight slip fit on the exhaust tube. The exhaust pipe goes in about twice as far as the cuts and bottoms out on the slip in baffle.

The mufflers come with a chrome universal mounting bracket with one hole drilled in it. The muffler has a bolt sticking out the side and you need to find a place to hang the steel strap. To keep the stock rear peg mounts I needed to re-use the stock muffler brackets which have two holes. So I drilled a second hole in the strap and bolted it to the stock bracket. Then I measured and drilled a third hole in the strap for the muffler to bolt into. This process had me taking the exhaust on and off the bike multiple times to make sure everything lined up correctly.

Once it was all dry fit, I pulled the exhaust and drilled a 1/8" set screw hole in the muffler and exhaust pipe. Then I pulled it apart applied more Exhaust System Joint and Crack Sealant and put it all back together. Finished exhaust... no welding.

With two exhaust pipes in hand I pulled out the 1" wrap and proceeded to wrap the pipes. I was taught to start at the muffler and worked my way forward. This way the air is flowing over the seams not running into them. Think of it like rain going over shingles on a roof.

Two wraps at the base of the muffler and a hose clamp to keep it in place. I continued wraping by overlapping each wrap with 1/2 the width of the wrap and finished about 3" from the head of the exhaust. You need to leave room to get the exhaust clamp and clamp locks in place. I finished the wrap by crossing the last wrap under itself and carefully cutting off the "tail" with a box knife this in effect creates a knot at the end of the wrap. Then a second hose clamp over the knot keeps it from untieing.

The end result is a cool old-school exhaust with a header pipes that could be reused to remount stock mufflers. These mufflers create a little deeper exhaust note and I think they sound pretty good! It'll be interesting to see if we will need to re-jet the carbs to make up for the lower restriction exhaust.


  1. Hey, I have followed your blog for a few things and found it very useful/interesting (especially the Clubman install...). Anyways, what do you think about the shorty exhausts on the 200? How much louder are they actually than the stock exhausts, and did you ever find that you had to re-jet, or did you leave the carbs as-is?

    Nice looking bike. I have a '75 360t that I am slowly beginning to cafe....

  2. Better make sure that your installed muffler will
    give you increased engine efficiency, performance, power output, and simultaneously decreased overall wear and tear on the engines' components