Exhausting Work but Worth the Effort

With the frame done it was time for the exhaust. I really wanted something nice and Scott really wanted a rest but there isn't anything nice for BMW's on the market - it's all basically 2 into 2 systems with crossovers. There's nothing really wrong with it but there's nothing really right either. I spent some more time in Photoshop considering options and then made some phone calls. We were going to have to build this part too.

Michael Moore of Euro Spares put me in touch with Craig Hanson of Hanson Racing Technology (check out Craig's BMW or his other bikes) who knew a lot about racing BMW's and has built some very stunning bikes. Craig created a "kit" for me based on the displacement, cam and cam timing and several days later I got a box with a bunch of curved tubes and some drawings from Craig giving me the critical dimensions that I needed to adhere to. My job was to figure out how to make 100 some inches of exhaust pipe fit on the bike. Craig's instructions were that it could be as twisty as I wanted (think F1) but I had to make the lengths EXACTLY as he specified otherwise all his dyno and flow work were worthless. I wanted the system to be as short as possible for to show off the single sided swingarm so I cut vacuum cleaner tube to length and began to play with options. By taping aluminum welding rod to the tube I could get it to hold position. From there it was a matter of cutting the 180° bends to create curves to match my mock up.

Scott holds the completed exhaust (bottom) - one serpentine and sexy collection of tubing. The goal was to match the initial down angles of the headers as they came out of the engine and then try to match the curves while getting the headers to end together. By using the natural offset angle of the cylinders we came up with a very attractive and perfectly matched and tuned header. Now we ship it off to HPC in Oklahoma for a "polished aluminum" ceramic coating (to match the tank) that will look good, protect the pipes and supposedly add some performance by helping to extract exhaust gases.