thought something might be missing
sam,
i'll look thru some other things i got with this setup to see if i can see anything that might fit. there is a long piece on the one pipe but i can't see anywhere it would fit. i would like to get it set up before the race. i did however pput a few squirts of fuel in the carbs and did get fire and got the attention of my grandson.
frank
engine has movable "eyebrow" exaust port
The short cable with the bolt attached to the end attaches somewhere (maybe the flat piece with the hole in it) so the "eyebrow" in the port raises and lowers as the pipe is moves back and forth, effectively raising and lowering the exhaust port timing. If I'm not mistaken Brinkman and Harrison gave up moving the "eyebrow" in conjunction with the pipe most of the time, as they found there was not much advantage versus the problems of keeping the pipe and port syncronized. I had this type set up on a 125 made with a Honda cylinder with same type port, but we used a second cable wrapped around a capstan to move the port more positively and you could also vary the timing between the port and pipe. On that smaller displacement engine (1/2 of what you have) it was advantageous to move both at the same time. We also had to have a positive connection in some manner to hold it at the highest position if we weren't moving it with the pipe, or combustion chamber pressure would "blow it down" and the engine had no power.
Short and sweet, you might be better off to just tie the port up (highest location) and move the pipe only. That is what I would try first if you cant figure the linkage out. There may be very little to be gained the other way.