1982 250yz power valve

[JJDirt]

I just redid the engine on my bike, deglazed it replaced the gaskets, piston rings, and o rings. I put all back together but when i went to finish up with adjusting the lever on the power valve i noticed the power valve itself sat one of two ways, 180 degrees different. I'm assuming the concave is either facing in or out, but the manual i have for the bike mentions nothing about where it should sit, it just tells me how to adjust it with the lever.

Anyone able to tell me how it should go?
Ex. Concave in at TDC.

This is my first time tearing down an engine, I don't want to blow a gasket because it isn't sitting right.

 

[whenfoxforks-ruled]

When would you think the exhaust would need to be bigger? At idle or wfo? Vintage Bob

 

[JJDirt]

Well I would assume there would be more exhaust when your full out but compression would increase the power so having it closed or partly closed would create more power, I don't know enough to make any bets on it, and the guys at yamaha won't tell me without them ripping the engine apart and assemblying it to "guarantee" it's done right, since I don't have the money for it and I would rather do it myself so I learn, that isn't happening. I'm not even sure if it can be explained or if it depends on certain variables. I'll try to upload some pictures so I can show what I mean.

 

[whenfoxforks-ruled]

WFO means wfo on the exhaust valve also. Off idle, smaller area means better bottom end. If you really want to learn, the shop manual for that bike is in order. After that, check out the books from Eric Gorr at Forward Motion. If you are still interested, check out Professor Blair. If you are too thrifty to buy a owners manual, how on Earth are you going to keep it going/routine maintenance? I am as cheap as it gets! And sorry, I do not have a manual for that bike. A parts micro fiche can help, but there are specs in the book, and some parts have to be put in in sequence and lining up timing, of sorts. The exhaust valves on some 2 strokes can get pretty complicated, and finicky about being put in wrong. Vintage Bob

 

[JJDirt]

I have the manual, and this is the first time i've ever done something like this so I am looking for a little bit of help from outside sources. I've talked to the mechanics at yamaha and they can't tell me what to do without tearing it down. Also talked to a bike mechanic but he's unsure of it because it's older than what he works on. I can feel it when my exhaust is off, either theres a concave or theres not. I'll check out the books from Eric Gorr if I can get them through a library but thanks for the help I'll keep searching for some info.