Seized Stage 4 steel barrel

[jason frost]

What's the piston ? Any tuning ? Piston to bore clearance ?

[Muppet]

cant see any chamfers on any ports

[holty]

cant see any chamfers on any ports

yes thats a good spot, they look like very sharp corners to me, barrel just wants a light hone, someone suggested a cheap 3 legged one off ebay, its a good idea, piston doesnt look to have been running weak as its very black, maybe clearance wasnt correct in the first place, or hasnt been run in correctly, i wouldnt faff around cleaning up the piston, just replace it with the best one you can afford, hone barrel and chamfer the edges of all the ports,check piston clearance and ring gap,and run in very carefully, check for air leaks just in case, use a quality oil as well. sometimes jetting can be wrong and it doesnt show up unless its thrashed enough, i wrecked an engine like that earler this year, maybe your main jet is too small, i like to overjet till it bogs at full throttle, then come down to the next lowest jet that it doesnt bog on, it doesnt give the best power but will make the engine run cooler and be more reliable, ive gone on a bit there, you probably already knew everything ive just said, hope you get it sorted,

holty