While cleaning the carb on one of my DT360As I noticed that the low speed and idle fuel circuit outlets do not align. I'm curious as to whether it is important that they do align. They do interesct but not on-center. I'm thinking the part of the at-idle airflow that does flow under the slide is concentrated to the middle of bottom of the carb bore but must flow around the needle jet shroud so it is likely trubulent enough to make a precisely centered location unimportant. Comments wellcome.

What's important is that the front hole intersects with the hole under the slide down inside the carb.

Hole under slide ("bypass") doesn't provide fuel at idle. Fuel starts to flow from the "bypass" hole under the slide as the slide lifts. (Small diameter carbs don't have the "bypass" hole.)

I don't think it matters that they are not in line... unless they don't connect inside the carb body.

As Mark says.
Think they're called a progression hole or something, & bridge the gap in carburation between idle & fuel being drawn up past the slide needle. Feel free to update me anyone, guessing a bit lol.

Actually 'no', just thought again & i'm wrong, & if i'd read Marks properly i'd have realised before making a fool of myself again lol.--- progression hole is straight up & the angled one is the idle hole. Think it's possible to alter the progression a bit if say it's a bit lean just off idle, then if you go a step larger in the pilot & you can then lean off the air screw a bit to correct idle but still have it richened just off idle if that's what you're wanting. Mind you slide cutaway then has some affect -- i give up. You'll have me checking all 'my' carbs now.

Yes, lean was the issue.

While cruising in high gear on secondary roads in the 45 to 50 mph range the bike chugs along easily with barely any throttle. However it would misfire like there was an ignition system issue until the throttle was opened further.

While inspecting the low speed circuit of the carb the misalignment was discovered.

Last night I put a freshly cleaned carb on from another in-progeess DT360A that has the idle circuit port on-center.

During inspection before install it was found to have a #60 pilot. The one with the off-center idle port has a #45. The service manual calls out a #60 in the General Specifications section and a #50 in the carb section and parts list.

I'm happy to report the on-center idle port carb with the #60 pilot cleaned up the misfire. I suspect it is because of the larger pilot and not because of the idle port centered location.

This weekend I'll put the off-center port carb back on with a #60 pilot for a more apples to apples comparison.

Ok, interesting times. from how you described it i'm sort of thinking needle clip position might come into play, or cutaway. Bit of trial & error but interesting what you found changing carbs. Was that using the original slide with needle set as it was. Needle jets 'do' wear but only real way to prove that is replace that [emulsion tube] & needle.

Right, I left the slide and needle attached to the cable when the carb swap was done. I should have mentioned this. Thought about mentioning it but got lazy and didn't!

Haven't tried moving the clip, yet. I did do the drill-bit-shank-in-needle-jet-bore check on the first carb and it looked round with no discernable out of roundness. The needle looks to have an even finish with no polished areas. I have not been able to find the needle as an available part but the needle jet is available.

I'm looking forward to putting the larger pilot in the first (original) carb and evaluate it this weekend.

Moving the clip down a notch would be an interesting test as well.