I had my 1970 Norton 750 engine rebuilt MAINLY because it leaked oil from the case halves after 45 years. After spending $1700 CDN to rebuild the engine ( a 2 cylinder only ! ! ! ) completely right down to main bearings, it does NOT leak from the case halves any more, however, I had to completely remove the top end again and replace the rings as the mechanic broke the oil scraper spring tip off during his repair job rendering the oil scraper useless. It burned so much oil I could not see. The base gasket was also so damaged that the oil poured out of the front of the engine. The combustion chamber on one side had aluminum chips inside and one was stuck to the valve seat causing it to backfire. This mechanic was recommended as being good at rebuilding vintage British bikes by a vintage parts supplier. Just be very careful. Watch out for the dirt floor and the chipmunks running around on the workbench. Never liked poetry very much either. He's much better at that than rebuilding vintage bikes. :-O.
Oil drips from British bikes can be fixed,but not without completely dismantling the engine and chamfering the relevant holes (the ones around the oil) also,gasket sealer may be used.
British bikes leak oil because the crankcase bolt holes need chamfering,because,metal is pulled up into the gasket when bolts are tightened, causing leaks,not particularly easy to fix,but if you can dismantle a engine succesfully,it can be done,of course you must put the engine back in running condition.
Interesting about the bolts pulling the surrounding metal up into the gaskets. Never heard that. Makes sense. What was your source for that info? I guess everywhere there is oil, chamfer the bolt holes?
Wow! shows its possible! I plugged a leak around a head bolt ( yes i know it shouldnt leak there ) only for the one on the other side to start leaking, telling me its a lot to do with oil pressure. 😯
Why do british bikrs leak oil? The gasket between the two crankcase halves gets ruptured by the metal rising from the female side of the crankcase which can be cured by chamfering to prrvent this condition.