Pro-x vs Sphinx jetting

[phil_koliss]

I have a 344 Sphinx ported by Arlan at LED(mx low port).I have his hand coned big bore pipe and muffler (built 2015) and intake,  He suggested/recommended me 48 pilot, 178 main with  a DEL 3rd or 4th clip at 2000-2500" elevation as I run a 38mm A/S. Now, I know a few guys that have similar set up with pro-x/ESR type cylinders and bigger carbs recommend way richer jetting, and tried but seems more sluggish and plug looks rich. I feel like I could lean it more, but dont feel like burning a piston to learn just to go with my gut, I'm not that stupid lol.
What I have I  here right now is 178main, 48 pilot with CEL 3rd clip. I'm happy how it runs, just deceivingly fast. Just want feedback by guys who really knows engine dynamics,  I don't feel like bothering Arlan. Busy guy and too much respect, as I know how it is to stop what you do to answer 1001 questions, which some of them might be deemed as stupid.  
So basically my question is better flow smaller jets makes sense?(sphinx vs pro-x) Stronger intake signal also equate smaller jet(38mm carb vs 41.5mm)
Sorry for the essay but read so much this is how I see it. Just want to be corected if I am wrong, too much money in this to just have it blow up on me.

[Jerry Hall]

If Arlan recommends DEL needle, why are you running a CEL needle?  I would try his set up first and start tuning from that point.

Keihin theory says that the main jet controls the fuel flow to the engine in the 3/4 to full throttle position but needles can/will affect the main jet.

While dyno testing we often see the carb take the same main jet size with different needles to get the same fuel flow and power at wide open throttle.  Some needles may take a 200 main jet to get the same fuel flow to the engine where a 170 was optimum with a different needle or even moving the clip a few positions.  

Start off with a large main jet and work your way down.

 "C" series needles have less taper than "D" series needles.  As a result of less taper, the "C" series needles usually have larger diameters at the small end of the needle.  A larger diameter at the small end of the needle most often will require a larger main jet than when using a steeper taper "D" series needle.

[phil_koliss]

Thanks to make it so simple Jerry. Makes more sense now. Only reason I have  CEL and not  a DEL is availability. I have to order and has to cross the border to Canada. Plus my local shops can't figure out what DEL means so when I will order from Sudco more jets, I will buy a few more needle just to make shipping worth it. Asking keihin jets and they look at me like I have a nipple on my forehead. If it doesn't have valves and 2 wheels, or minimum 2 seats, not worth it.
My plug reads a bit on rich side and my temps are 180 when cruising 4 or 5. 3 gears in tighter stuff it flirts with 210 the highest I seen it on ESR gauge. Seems to be fairly close to my infrared temp meter I have for work so cant be that far off.
Thanks again Jerry for your wisdom

[Jerry Hall]

Jetting that is lean enough to burn a piston will not increase the coolant temperature significantly over jetting that is spot on.  Coolant temperature is more dependant on the amount of power the engine is making, condition of the radiator, the air temperature flowing THROUGH the radiator and amount of air flowing THROUGH  the radiator.  

Look at the Sudco catalogue at the Keihin needle charts.  It will show you the dimensional difference between a DEL and a CEL needle.

[phil_koliss]

DEL installed. Had to give local shop owner sudco part number to find it. Thanks again Jerry for your time clarifying temps for jetting. Now for part 2 of the question,  will different porting(mx vs dune eg.) or cylinder(ESR vs Sphinx eg.) of same displacement have pretty close jetting assuming other variables are same(carb, pipe and builder etc.) Just curious.