I would have thought it pushes the piston down a bit further with the main effect of idle enrichment due to higher air speed across the jet - apparently not - but I have another idea. If the jet is worn (I‘m sure I checked a few years back) then the biggest impact of this wear would be around idle (fatter). But it would also enrich the next zone, with idle adjustment correct it would lean out at the top end, and maybe the UB masks that… oh it’s complicated. I‘ll try timing first.
1 Like