250cc harrison question

[fbref5269]

hi all,

welll i may be getting wet again this time in the 250 class. i picked up an '84 250cc kay harrison yamaha, etc on a pugh hydro. the number on the boat is f7. my question is this.... there is some contraption on the stack side of the engine that looks like it is connected to the stacks somehow. as the stacks go back the contraption moves. i've attached some pictures of it and was wondering if anyone knows what it is and where it goes? i thought it attached to the bar on one of the stacks but it won't fit. any idea who had this rig in fla and any way to contact him?

thanks for your help. lock haven here i come. also bringing the quincy a looper and takinfg it for a ride alomg with a 125 quincy z engine. i starting to feel like bobby thornton. reffing a high school football game friday night then driving to lock haven.

frank

[Mark75H]

I'm surprised Mike Schmidt hasn't beat me to this ...

its an exhaust port control, lower port for lower rpm's; higher for higher rpm

If I could see it in person, I'm sure I could correct the hook up

Mike may know it well enough to tell just from the pic, I think he built the same thing

Do both pipes have brackets like the one we can see? Looks like the cable might go

to the common connection between them with a little bracket that helps you adjust the

length to the rack.

What I am saying is ... I think a bracket is missing that sits on the struts that go to the pipes.

The end of the cable looks frayed, it may have originally been long enough to reach all the way

back to the common connection point; but you would still need a length adjustment feature to

make everything work together

[fbref5269]

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

[GarE-12]

The long bracket, bar, is a standard connection between two pipes in conventional staggered, configuration, it ties the two pipes together so they move as unit.

[Bill Van Steenwyk]

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.

[Mark75H]

The long bracket, bar, is a standard connection between two pipes in conventional staggered, configuration, it ties the two pipes together so they move as unit.

I think the set up is the same as the Kaw that Matt Nolette has/had.

So the bar connects to the other pipe closer to the motor? The port control cable shouldn't have much trouble connecting to the left hand side pipe

Gary, do you know where Matt's boat is? Is it for sale?

[GarE-12]

You have to make sure the pipes move together, then just clamp down the port where the thing will run. I may be there to help out and there is no joy like fabricating complicated mechanical systems in the pits with bailing wire and beer cans.

Did the pipes come with the motor and/or were they used with that motor?

Will check my sources concerning Matt's boat.

[John Schubert T*A*R*T]

Frank,

I sent 2 e-mails to you about the transom pad installation tool, but haven't had a response. Probably too busy to check your e-mails.

[fbref5269]

john,

going out this morning.

frank

[Dave-4Q]

That was Matt Notools boat !!