Working on an ‘81 Panther with the 440 fan. Sled’s in great shape @ < 400 original miles. Bogged when I first purchased/ran it. Oil injection check valve appeared to be bad/flooding case with oil, so disengaged linkage to carb/ran pre-mix and replaced fuel lines, pump, cleaned tank/carb, and some minor touch up - usual stuff. Now it won’t even fire. Both cylinders have 130+ lbs (haven’t done a leak-down, but bad seals shouldn’t cause this…?). Had to adjust TSS, but it’s fine and have good/solid spark on both plugs when grounded to fan shroud. Pump is pushing fuel and cleaned carb looks good (float/needle/jet/Venturi all appear to be fine). Even with a little fuel in the cylinders and starter fluid through the intake (which is clear), not even chugging/firing at all. Never had this issue with a sled that had air/compression, fuel, and spark. Wondering about a timing issue, but haven’t done anything to impact timing from the original issue, where it ran, just bogged at higher rpm. Would really appreciate any input/thoughts…., Thanks.