Drilling out the slides for quicker carb response?

Was reading up on this Mod for the 38 ML Diaphram style carbs for I assume quicker
response especially the low end between 2000 to 3000 rpm.I notice my bike has a slight
flat spot in that rpm range.If I crack the throttle of the line it will pull hard all the way to red line or
if I'm running along at 4 grand and crack the throttle it will pull hard up to red line.But run in a high enough
gear were the rpms are at 2 to 3 grand and hit it hard it won't pull as hard like theres a slight dead spot were its either to rich or to lean, not sure.I am running 30 pilot(up 2 sizes) stock middle setting on needle(middle)
and 135 mains.I have tried dropping the needle 1 clip but had to go back to stock middle setting or mid range felt flat.Big difference. The 76 and 77 had really rich mid range needle jets compared to any other year and
what works for others doesn't seem to work for mine. Talked to MMM and he advised me to try drilling out
the slide and/or dropping the pilot one size.Anyone try this slide mod and can comment, from what little I could find this sounds like a Minton Mod.

If you care to dig the old Rider site had some discussion about it. IIRC XSJohn tried it and felt he ruined a set of slides BUT those were 34's.
There was also some discussion about tying two or three of the spring coils together with zip ties to mimic the effect. Don't count on my memory though.

D, you write that low rpm throttle response is lacking only when running "in a high enough gear." With all respect, the problem may be in your expectations rather than your carburetors. At 2K or 3K rpm the XS650 motor isn't making much power, and at those revs you'll get a strong reaction to the throttle only in the lower gears. And yep, even with some fairly strong hop-up mods, you're probably one step fat on the PJ's.

As to those "lean" NJ's: there's an inverse relationship between MJ and NJ selection. The difference in size between a Z-6 and a Z-8 is a single step (the only odd number in any Mikuni letter sequence is -5). The performance impact of that single step in the very fat Z jets is negligible; from the fattest Mikuni NJ of the series to the next-to-fattest.

I guess my question is; will it pull well if you smoothly roll in the throttle from 2K up into the powerband in a high gear? If so I'd suspect the slide is already going up too fast. But I know little or nothing.

I have a friend with same bike, same compression, carbs and ignition ect( only difference is his has the old Mac pipes with stock head pipes)
I have the Mikes xs pipes.His feels really strong all the way thru at any speed or gear, no flat spots.His doesn't need to spool-up like mine,
its always there.He is running the stock gearing and I'm running a 33 rear.Not sure if that could be the reason.He has the pilot up 1,needle in middle and running a 132.5 main.Could the pipes account for the difference.I have ridden a few of these and his 77 runs really strong and smooth, amazing really.
I will try dropping a pilot size,nervous about drilling the slide.MMM stated that that it will either work or not but won't make anything worse.
Thx for reply

Dropping a single tooth at the wheel won't have a large effect on acceleration. When you write "the Mike's XS pipes," do you mean the Mike's XS replica exhaust system, the Mike's XS 1-1/2" chrome pipes, or the Mike's XS 1-3/4" stainless steel pipes? Are you running those pipes with a muffler or without? Once again, eliminating the muffler entirely will result in a narrower power band, and 1-3/4" pipes will move the torque peak up in the rpm range.

Another thing to consider is ignition. If you use a system that retains the OE mechanical advance, that can be a source of trouble.

1.5" Headpipes with tipped up ends (from Mikes) and Commando mufflers( from Mikes).He,s running the stock head pipes and Mac exhaust. I think there less restrictive
and definitely louder.Yes I have the original mechanical advance with Mikes xs springs (which suck) He has the same but with original springs (big difference in smoothness off the line and at low rpm riding in first gear. Apparently those Mac mufflers are set up for better low and mid than the Commandos so he stated.

I doubt that mufflers are making the difference. The OE head pipes are double walled and have smaller ID, but again, the 1.5" pipes work very well. Springs aren't the only issue with the mechanical advance. What happens under the strobe?

Just did another check on Timing with my New Timing light (finally) Idle at right side off F but within the 2 lines.
Full advance approx 1 mil retarded off advance mark.Checking the advance while slowly revving engine looks like its
starts moving around 1600/1700 rpm and hits full advance around 2900/3000 rpm.Hard to do by myself, need an assistant, maybe one
with nice legs! Lol .Strange thing with this new Timing light is it will stop strobing when the advance gets near the full advance mark, wont do it
at idle or off idle.Is that normal, never had one of these before, strange.I would think it would keep strobeing until I released the trigger.
I realize this isn't a bike question but if anyone has experienced this with there Timing light.