Update:
I got the supposed 24mm Mikuni today....Port size at attachment flange is right at 25.72mm ...SO 26mm... HOWEVER, it matches the bore of the manifold VERY well and the manifold matches the engines intake flange as well....No problems to this point.... My problem with this carb is the VENTURI looks too small to be a 24....Here's my calculations and method:
First, I picture the actual opening at the venturi as two half circles (one top, one bottom) with a rectangle in between..... This means the area of the venturi is the sum of the rectangle and one full circle....
Width of opening is 16mm....length of opening is 25mm....This gives me an r= 8mm circle, plus a 16 x 9 rectangle.....
Area of the circle is Pi x R squared, so 3.14159 x 64 = 201.06 sq mm
The rectangle adds 16 x 9 = 144 sq mm.....= 345 sq mm total......
Divide by PI and take the square root will give the equivalent circular radius....=10.479... the equivalent diameter is twice that, or 20.958 (approximately 21mm).... Not close enough to 24mm in my books...
Even allowing for measurement error and rounding during calculation, that means it is at best a 22mm venturi equivalent carb..... Certainly NOT what I ordered/purchased, but actually perfect for my needs.....
LOL.... looking closer, it has 22 , (and several other numbers) stamped into the flange (including 230, s3, and 3847)......
Anyhow,...To the point of this post, ....Anyone have jet sizing that works on a 125 engine with a "24" mm Mikuni???....Currently has a #15 pilot and a .95mm main (seems about right on the main...Or maybe a 105?).... Might save me some time and $.......
Thanks, Steve