Long story, had a few years trouble, head was leaking oil into the chamber, mixture lean. 1971 t120 motor.
Removed and reseated head with new head gasket and the proper large washer. Same story, sort of.
Redid it again over the winter real slow... checked head for straightness, etc etc... Had the seats machined flat where the large washes go...
Used new inner and outer head bolts as I found a little necking on one old one. Bolts were from TMS (recommended on this forum).
Torked head up, left for few days and torqued again, Ran it on a short ride for 15 minutes and torqued again. At this point most of the bolts had moved about 45 degrees from the very first torquing position (dab of white paint marking). Did tappets, etc.
I planned to retorque again after 250 miles.
But after I ran one tank of gas though (150 miles?) I heard a strange sound (like exhaust escaping) and so removed tank to inspect and retorque. I tried to loosen a quarter turn before torquing first bolt but realised there was no need as the bolts moved too easily.
I retorqued everything and found all bolts to be a little loose. The final position was now about 90 degrees for most of the bolts. I adjusted the tappets and found all to be tight, almost no clearance.
On top of that a close inspection shows that head gasket had blown and some gas was escaping from the side of the cylinder.
I'm starting to wonder if the head is not made of inferior material, or possibly was overheated and has weakened, I doubt it's the bolts as head has been problematic before.
I'm going to run after the retorque and see what happens. Either way I can probably not spend any more serious time on it until next winter so I've not got much choice but any ideas or advice greatly welcomed.
A bit depressed BMF....