After reading some other threads, I see there are some very knowledgeable people here. So it seems a reasonable crowd to toss a question to.
I have an '83 YZ250, have had it for years and love it. What I'd really like to do is tone it down and make it a better trail bike as that's 95% of what I do with it nowadays anyway. The suspension still needs some work, but I've got a handle on that. I can't find where flywheel weights are available or different spring rates for the power valve (doesn't use springs anyway). I guess the timing could be messed with, but that's an area that I know very little about. When I got the bike it was geared taller than stock, it was at 14/48 (stock 13/48) and I re geared it lower to 13/50. I recently rebuilt the top end on it and found it to be .080 over but ring gap is at the minimum spec so it's tight. In the process, I changed the stock reeds for TDR reeds and I've jetted the stock carb. It does have a DG pipe and silencer and I've added a cobra spark arrestor. I've noticed the '84 has other more modern pipes available, but this one the pipe runs off the left side instead of the right so a bit of modding would have to be done to change to a different pipe.
It runs really good and has a really strong punch in the mid range. I'm mostly curious what, if anything, can be done to broaden and perhaps mellow out the power a little more for a better trail/woods rider on this thing.