Don't know anything about Kombi's, but type 3's with twin Solexes's always had a bigger air-corrector jet on the LH side (passenger's side) carb. (Except '71 on according to one Manual, but not the other). I eventually decided this must be as the main on that side was always slightly bigger -- in order to make no. 3 cylinder slightly richer (so it runs cooler).
VW must have got worried about no. 3 cylinder early on as all later AirCooled engines seem to have at least some bias to helping it run a bit cooler. The type 3's spec's above were for air corrector jets of 155 or 150 on LHS, and 120 on RHS. The corresponding mains are only slightly different eg. 130 LHS & 127.5 RHS.
Air Correction jets are only meant to affect the running of the engine at higher rev's, and so probably have nothing to with flat spots at low to mod. revs. Maybe one of the mains is partly blocked, or an accelerator-pump not working?
If you're going to change jets, there's a good technical article at
www.aircooled.net "How to Jet your Carburretor/s". Describes the function/s and characteristics of idle, main, air-correction, and accelerator-pump; & how to experiment. We've fiddled around with jet changes recently. Came back to settings exactly as per the Manual on one car (1600; single Solex 34 PICT-4: 127.5 main), BUT had to use at least 140 mains instead of the standard 127.5/130 on a 1640 with twin Solex 32 PDSIT's. Probably depends on the individual engine! (I think you should have any other "issues"/faults sorted out before you start to fiddle with carb's.)
[ Edited on 19-1-2006 by ACE_76 ]
[ Edited on 19-1-2006 by ACE_76 ]
