As said the idle jet size also controls the fuel mixture above idle for a fair way.
Idle jet size should be selected to get it running clean just above idle without an acceleration flatspot. If the idle screws need to be screwed a long way out the jet is too small, as feral said..
Fer example, in my case (Dellorto 45 on a 1310, then 1360) I ran it for years (34mm chokes) with 50 idle jets, but when I went up to 36 and then 38mm chokes I had to upsize the idles to 55s.
Check what emulsion tubes are in it, but if it was OK before they are probably right. Usuals on a Weber for a Mini are F2, or maybe F16.
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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.
