Dustdevil
Race Dog
A client have recently asked me to replace his entire exhaust system on his 85 G/S.
Naturally there is nothing of the shelf to fit these bikes locally and BMW only supplies header pipes.
Getting a generic tail piece to fit using Powerflow headers and collector box ended up being the last resort.
Nothing to be said about Powerflo, it sucks....like usual! The collector outlet angle is completely off. The only solution is to cut it of and re-weld. Not an easy task as the material lost from grinding leaves large gaps to be filled. Fortunately they use such heavy gauge material it is much easier to weld, but then the parts themselves are much heavier than what they really need to be.
The tail piece is a Spark GP Style from Motobakker
What a pleasure working with the Spark components. Real great quality but made from very thin wall S/S. If you don't want to burn through the material there must be no gaps in fit-ups....I mean nothing, nada, zilch!
In the pics below you can see the huge hole formed through having to rotate the outlet to eventually point in the right direction. Cutting the Powerflow open was an eye opener as these guys do not even bother to remove the cutting burrs on the inside of the tubing much less do any purging.
Some might wonder what purging is. The short explanation is that when welding really thin stuff the metal on the inside of the tube also melts to an extend and when in direct contact with air it forms a crystal like structure on the inside of the tubing. This stuff makes ridges that interferes with the flow of the gasses but where tubing must fit over each other it will make it impossible for the smaller tube to fit into the bigger one.
Purging is a simple process where one purge the air out of the tubing or exhaust system with the same gas used for TIG welding. Argon is heavier than air so by closing of the ends of the tubing with masking tape and running a small tube that blows argon straight into the exhaust, the air is forced out the top where a small hole is punched in the masking tape.
My simple purging system connects inline to the gas supplying my welder. A small clamp is used to regulate the flow of gas.
Naturally there is nothing of the shelf to fit these bikes locally and BMW only supplies header pipes.
Getting a generic tail piece to fit using Powerflow headers and collector box ended up being the last resort.
Nothing to be said about Powerflo, it sucks....like usual! The collector outlet angle is completely off. The only solution is to cut it of and re-weld. Not an easy task as the material lost from grinding leaves large gaps to be filled. Fortunately they use such heavy gauge material it is much easier to weld, but then the parts themselves are much heavier than what they really need to be.
The tail piece is a Spark GP Style from Motobakker
What a pleasure working with the Spark components. Real great quality but made from very thin wall S/S. If you don't want to burn through the material there must be no gaps in fit-ups....I mean nothing, nada, zilch!
In the pics below you can see the huge hole formed through having to rotate the outlet to eventually point in the right direction. Cutting the Powerflow open was an eye opener as these guys do not even bother to remove the cutting burrs on the inside of the tubing much less do any purging.
Some might wonder what purging is. The short explanation is that when welding really thin stuff the metal on the inside of the tube also melts to an extend and when in direct contact with air it forms a crystal like structure on the inside of the tubing. This stuff makes ridges that interferes with the flow of the gasses but where tubing must fit over each other it will make it impossible for the smaller tube to fit into the bigger one.
Purging is a simple process where one purge the air out of the tubing or exhaust system with the same gas used for TIG welding. Argon is heavier than air so by closing of the ends of the tubing with masking tape and running a small tube that blows argon straight into the exhaust, the air is forced out the top where a small hole is punched in the masking tape.
My simple purging system connects inline to the gas supplying my welder. A small clamp is used to regulate the flow of gas.
