tok-tokkie
Race Dog
I wrote this for Chain Gang so some American words are used.
The twin spark Dakar exhaust has left and right mufflers each with outlet holes. In fact the left exit is closed so all the gas comes out the right muffler. Previously there was a small 'pea shooter' exit in the left muffler; just take a look at yours to see which one you have.
Here is a diagram of the twin spark exhaust
I wanted to free up the space taken by the right can for a toolbox so I needed to open up the left can. I bought a 27mm hole saw; it slides neatly into the outlet pipe. If you look into the closed stub tube you will see that the sides of the pipe are squashed together to form a 4 pointed star & welded shut along the edge. I wanted to cut this off with the hole saw.
There are three different types of stainless steel: 1. Martensitic which is what your Leatherman and knives are made of. 2 Ferritic which is magnetic (as is martensitic); your kitchen sink & fridge (if it has a stainless box) is made of this type & 3. Austenitic which is non-magnetic, this is the type used most commonly in engineering. There are several grades of austenitic but the most common are 304 & 316 (all the austenitic grades are in the 300 series & the ferritic are the 400 series (I belive).
The Dakar exhaust is non-magnetic & therefore austenitic. The big thing to know about austenitic stainless steel is it work hardens and this has a big bearing on doing this mod. Work hardening takes place when a cutting tool such as a drill or saw slides on the surface instead of cutting. Once stainless has work hardened it is too hard to cut with a drill or saw â?? all you can do is grind it with a stone in a high speed tool such as a Dremel or vaporise it with an oxy-acetylene flame.
I therefore did not attack my exhaust with the hole saw fitted to my hand drill. Instead I took some trouble in devising a way to clamp it to my drill press so I could run the saw slowly and apply constant firm pressure and cutting fluid while cutting. It is not very clear in the photo but I removed the table from the drill press and clamped the muffler using a v-block on top of the 45mm cross connecting pipe (that is the brass block with a slot) and a really good clamp I have. I greased the hole saw so it turned freely in the stub tube of the muffler. The hole saw is white so does not show very clearly.
Once I had cut through the crimped end I tried to pull the cut off piece out with long nosed pliers. Although it was completely cut off it would not come out. I lit my oxy-acetylene torch & blasted lots of Joules down there â?? except they are calories when you get across to your side of the pond â?? sufficient to make that little stub bright cherry red. Then I squashed the stub some more and yanked it out of there. Here is what it looked like once I got it out.
Those 2 pieces left by the saw were hooking into the steel wool packing in the end of the exhaust which prevented me from pulling the plug out.
I then pulled all the steel wool out; that required the application of more oxy-acetylene heat. Cut off the cross connecting tube & welded on a piece of stainless to close the hole. Fitted the muffler back onto the bike.
The exit hole is just the same size the previous one but the gas path is much shorter so there is less restriction. The noise is up quite a bit â?? I would not pull out the steel wool if I did it again. Now when riding on country roads people walking can hear me coming & don't get a fright when I come past. It could be a bit quiter but it is much quiter than some of the aftermarket pipes. I think the throttle response is better but I also know that if you hear instant response you believe you have better response. I also believe the fuel consumption has increased a bit- yellow warning light comes on at about 290 km instead of 310 km before â?? but again that could be different roads. I did a trip together with my wife â?? she on her F650GS and I put in 13litres when she put in 12 litres but I had panniers with all our luggage whereas she had no luggage.
I have since changed to another exhaust so this one is available should anyone want to try it out
The twin spark Dakar exhaust has left and right mufflers each with outlet holes. In fact the left exit is closed so all the gas comes out the right muffler. Previously there was a small 'pea shooter' exit in the left muffler; just take a look at yours to see which one you have.
Here is a diagram of the twin spark exhaust
I wanted to free up the space taken by the right can for a toolbox so I needed to open up the left can. I bought a 27mm hole saw; it slides neatly into the outlet pipe. If you look into the closed stub tube you will see that the sides of the pipe are squashed together to form a 4 pointed star & welded shut along the edge. I wanted to cut this off with the hole saw.
There are three different types of stainless steel: 1. Martensitic which is what your Leatherman and knives are made of. 2 Ferritic which is magnetic (as is martensitic); your kitchen sink & fridge (if it has a stainless box) is made of this type & 3. Austenitic which is non-magnetic, this is the type used most commonly in engineering. There are several grades of austenitic but the most common are 304 & 316 (all the austenitic grades are in the 300 series & the ferritic are the 400 series (I belive).
The Dakar exhaust is non-magnetic & therefore austenitic. The big thing to know about austenitic stainless steel is it work hardens and this has a big bearing on doing this mod. Work hardening takes place when a cutting tool such as a drill or saw slides on the surface instead of cutting. Once stainless has work hardened it is too hard to cut with a drill or saw â?? all you can do is grind it with a stone in a high speed tool such as a Dremel or vaporise it with an oxy-acetylene flame.
I therefore did not attack my exhaust with the hole saw fitted to my hand drill. Instead I took some trouble in devising a way to clamp it to my drill press so I could run the saw slowly and apply constant firm pressure and cutting fluid while cutting. It is not very clear in the photo but I removed the table from the drill press and clamped the muffler using a v-block on top of the 45mm cross connecting pipe (that is the brass block with a slot) and a really good clamp I have. I greased the hole saw so it turned freely in the stub tube of the muffler. The hole saw is white so does not show very clearly.
Once I had cut through the crimped end I tried to pull the cut off piece out with long nosed pliers. Although it was completely cut off it would not come out. I lit my oxy-acetylene torch & blasted lots of Joules down there â?? except they are calories when you get across to your side of the pond â?? sufficient to make that little stub bright cherry red. Then I squashed the stub some more and yanked it out of there. Here is what it looked like once I got it out.
Those 2 pieces left by the saw were hooking into the steel wool packing in the end of the exhaust which prevented me from pulling the plug out.
I then pulled all the steel wool out; that required the application of more oxy-acetylene heat. Cut off the cross connecting tube & welded on a piece of stainless to close the hole. Fitted the muffler back onto the bike.
The exit hole is just the same size the previous one but the gas path is much shorter so there is less restriction. The noise is up quite a bit â?? I would not pull out the steel wool if I did it again. Now when riding on country roads people walking can hear me coming & don't get a fright when I come past. It could be a bit quiter but it is much quiter than some of the aftermarket pipes. I think the throttle response is better but I also know that if you hear instant response you believe you have better response. I also believe the fuel consumption has increased a bit- yellow warning light comes on at about 290 km instead of 310 km before â?? but again that could be different roads. I did a trip together with my wife â?? she on her F650GS and I put in 13litres when she put in 12 litres but I had panniers with all our luggage whereas she had no luggage.
I have since changed to another exhaust so this one is available should anyone want to try it out
