Sure can't find any info on a starter jet.
Is it located in the hole where the plunger
is?
Upon further review, the last page in my old
Sudco book shows a starter jet or at least 
has a reference to it. I always thought the 
orifice was fixed on these carburetors.

2 & 1/4 is getting a fair way out for the mixture screw. I wonder where that wright up came from. Still only showing a 25 pilot.

Starter jet is in well in float bowl and not replaceable on that carb.  Don't worry about it.  Only used for starting cold.  Has no effect unless knob is pulled.

I'm sure there are a lot of bikes with original spec needle and main installed.  I think you're correct that revision leaned it out a little.  Make sure if you get new needle that you use main that goes with it!  (And stay away from keyster jets/slide needles)

Thanks for the help on this. Will order the correct stuff
from Sudco on Monday. D

Here are the Yamaha part numbers in case you need them and location of starter jet. 



 

I think the starter jet size might actually be a #40 drill bit?  Most Mikuni fuel jets (main and pilot for sure) are marked with a precisely calibrated "flow rate" but some air jets and maybe starter jet is drill diameter. 

 

Thanks Mark, good info to have!