T6 bottom end with t140 barrells and heads

[Metalmad]

Firstly hello to everyone I am new to the forum,although I am a skilled automotive technician I am a relative newcomer to the world of British motorcycles.I would therefore like to ask for people's opions on a fault I have on my bike.Its not strictly a triumph but is a triton with a triumph t6 bottom end and t140 barrells and head it is a pre unit from 1950s I believe.I did not build the bike but purchased it from the owner who had owned it since 67 he told me that the engine was rebuilt ten years ago using nos barrells and pistons and head and rods etc, it has since done about 2k the issue I have is smoking from the left bank (blue so its oil) worse on tick over and it fouls the plug when I look in the bore and into the intake the piston crown has a build up of sticky residue and there is engine oil in the intake track.I am thinking its a leaking or loose valve guide or a piston oil control ring fault before I pull the heads and barrells I just wanted to make sure I am not missing something obvious also the right bank is fine thank you for you're help .

[largeviking]

I've had a similar issue, mine is t140 head and barrells on a t120 bottom end. There was some play between valve and guide and the gap on the piston rings was over what it should be. These have now all been changed but was still smoking. Could have been residue left in exhaust or bedding in of valves and rings but since I drained all the oil out of the sump it seems to have stopped smoking.

[dunboyne]

probably sorted by now but in case not

see if its wet sumping for some reason , or if the oil is not draining from the head quick enough (possibly blocked hole in tappet block) this causes the oil to go up over the valve guide and of course down the valve as theres no seals. its more noticable on the left typicaly as the sidestand leans the bike that way .
hope this helps