The early Hinckley Triumphs are now in any case youngtimers.
The three- and four-cylinder models from the time before they got petrol injection had the reputation that they were rather inspired by Kawasaki. Scholars can argue about that, the fact is that the British were breathing in by Mikuni carburetors.
And there was - and is - a catch in those Mikunis. The gas works behind the Triumphheads tend to make the engine run very rich over time. Because 1 on 10 for a three-cylinder, that's big. Yet?
The venom appears to be in the plest float units, in the O-rings of those things. Replacement of it makes such a Brit roar again as it was intended.
Kawasaki used the same Mikuni carburetors at that time. And at Kawasaki's they never gave / give problems.
Those Japanese, anyway ... Would those cunning Japanese have simply delivered second choice to the British?