It's suddenly started running better, what's wrong?

[Eltoon]

Spanish 413 on original carb. Always started fine and idled slightly erratically but steadily so I never messed with it. Did notice than particularly on a downhill it would pop pop pop in the exhaust a fair bit on the overrun so I've always vaguely wondered if it was worth investigating...but not got round to it - there's always something else to sort! The other day after a successful ITV/MOT following steering box adjustment, I took it for a ride out and couldn't help but think it was running better than usual, seemed a little jauntier and responsive compared to normal and, as the run took me over our local windy mountain road, I realised afterwards that I hadn't heard any popping on the downhill stretches. The other thing I noticed was that the idle speed had risen significantly to about 1500 rather than the usual 700 - 1000 give or take. So, not really a problem as such.... and knowing my luck it'll be back to normal next time but any ideas what could have occurred here? I remember reading a comment/saying many years ago in me motorbiking days along the line that 'If your bike suddenly starts running really well, it's a sure sign of imminent breakdown'...

[ROBBIE]

The auto choke on the original carb normally goes wrong, which affects the idle. They are a pain to fix so most people just replace it. Popular replacements are SU hif 44 or a webber

[fozzie52]

The idle changes with the load from the alternator so if the lights are on/off this could affect the idle speed. Ive had my sj for 4 years and its got faster and faster each year just from being used regularly. Just an idea.