ORIGINAL: fullyford
the temps have gotten up above 300, but i like to keep an eye on it so its never there for long. had this problem for about 4 gallons. it does always seem to run awesome when first started, has lots of power, then once it is warmed up it starts boggin and not running good, i will try too lean out my lsn and richen my hsn, and see if that helps. there have been a few days where it ran great all day at 280, but i was always told thats too hot...
id guess new piston sleeve, if its 4+ gallons, if it runs at 280 and doesn't lean bog then run it man, don't be overly concerned about temps, more of an indicator then something to tune to, tune for performance then see what the temps are like. Usually as the motor gets older it has to run hotter to get the metal to expand more