Mac Header Reconstruction

[Jontheguru]

I'm in the process of finishing the immediate modifications to my 83 1100E. I purchased what I believe is a mac header, it looks almost identical to the ones for sale in dennis kirk. The baffle is nothing more than a squished pipe leading into a chamber than exiting out the end in an "s" shaped flow. I opened up the filter end of the air box so there is no restriction while still maintaining the integrity of the box immediate to the carbs. I have a stock replacement K&N filter for high flow into the latter chamber. I installed a dynojet jet kit as instructed. I tried various main jets and ended up with 127.5. It would not accept the 132's and was too lean anywhere else. The mid range was a punch, very strong, but the bottom end was non existant and would not run. I put in the 160 air jet to lean out the bottom end ( as instructed ); better, but still ran like crap. I pulled the baffle out of the pipe and was stunned to see the wacked configuration of the system. It was a risk especially when considering the complexity of pipe design but I had to try something. I cut the two pipes out of the two round baffle plates and welded in the same diameter pipe, except I ran it straight through. I than drilled holes in the newly installed pipe and wrapped packing around it and reinstalled. It looks very close to the design of the kerker header my brother has on his 86' GSXR. Most oldschool performance pipes have straight through baffles, just like I made. It took only a few carb adjustments and now it runs smooth and comfortable, even on the bottom end. The needles are on the 4th from the top and the air screw is out to 4 turns. I'm not sure how much of a difference it made on the top end because it wasn't dialed in before I made the change. The mid range doesn't seem as strong but that could be due to the drastic punch that was made from a non existant bottom end to a powerful mid. The true difference is that it actually runs pretty darn good on the bottom end and overall. In retrospect, I wish I dialed it in before the change so I could properly gage the difference, oh well, It's got plenty of power and is quite smooth. If anyone has any comments please let me know. p.s. I'm at sea level here in Portland OR.