Firstly I am new to this forum, and new to CB750's. My bike is a 70's era chopper with a rigid frame and a springer front end. My question is regarding the 2 bolt exhaust flanges that attach the headers to the ports in the head. I've had a 4 piece exhaust system made, which has all separate pipes with fish tales at the ends. The system was made in another state of Australia using another engine. When I try to fit the exhausts to my engine the two outer pipes want to sit at the wrong angle to the two inner pipes. From photos I know what the system looked like when it was made, and all 4 pipes sat together, running the length of the bike. Is there a chance the other engine may have had had different exhaust flanges fitted. Are there different flanges or are they the same for all CB750's. I am currently in discussions with the builder of the pipes and I am trying to make some sense of it all. Any help will be appreciated.