OK Eddie now that I have done some looking around I can give you the info that you need to help me out.
Info on the bike and conditions
92 RM 250
Elevation: Reno Nv, 4000 ft to 6000 ft depending on the area riding but mostly 4000-5000ft. Temp 60-70 F. Humidity 15-25%. Type of riding General desert trail and hill climbing.
Modifications: FMF Gold head pipe, FMF turbine core II. Air box is stock. Air Cleaner stock style Uni. Carb is stock currently running Boyesen power series reeds in stock rad cage. Engine is stock with fresh top end maybe 6 hours of ridding time (Wiseco Pro lite) 67 MM with 2 ring style piston set up.
Stock jetting 370 main 45 pilot. Bike is currently set up with 290 main 37.5 pilot, stock jet needle 2.60 mm. Jet needle set at #2 position from the top. Air Screw is currently 1 1/2 turns.
Running issue: Rich condition, fouls plugs after 3-4 hours of ridding. Fuel Oil mix at 32:1 per my suzuki service manual.
Changes in issue: No choke required to start unless really cold out side. After warm up period (2-5 min) blubbers badly up through the gears till about 3 gear then clears up through 4th and 5th. Will start to load up during technical trail rides. Will clear out if I open it up hard on a hill climb or straight section. Exhaust smoke is white during load up and tapers off but still visible during clear out runs. I always try to do a plug chop at the end of my riding and the plug electrode is a very dark mocha to near black color and slightly oily. Bike has a nice idle speed and has crisp throttle response (in neutral) with no hesitation or blubbering unless its loaded up.
All of these conditions started after I rebuilt the top end. Before my top end rebuild the carb was set up with a 40 pilot and 330 main jet with the jet needle set at the leanest setting. Plug chops revealed dark tan to light mocha colored electrodes. It just really baffles me why the bike would run more rich with fresh top end than it was before I rebuilt it.
