Hey fellas, hoping for some sage advice.  I'm pretty sure my carb is a Mikuni VM30-SS.  It doesn't have much imprinted on it except 'Mikuni' and it is the OEM carb.  The information in Clymer is somewhat contradictory.  Which of the attached photos is correct for the needle jet setup...O-ring jet setter or round 180 jet with washer?  Also, what main jet would you recommend at 5,000 feet?  My pilot jet is 50.  I'm planning to also change the reed set from stock to Boyesen dual stage reeds...thoughts?  Thank you so much for any guidance you may wish to offer!  Pat

Welp, it doesn't look like my photos made it.

Will have an "44560" ID number stamped if OEM carb.  On a spigot mount normally on the right side below starter lever or on front boss by starter lever.  

If original, should have a jet setter, o-ring, and washer in bottom of needle jet and the hex main jet is installed into jet holder screwed into left side of float bowl.  

Factory Service Manual available in Tech Library here.

Thanks Mark!  Just went down with a very bright light and my spectacles.  On the case surrounding the kickstarted shaft it says "KICKSTARTER' and above that and a little forward it says "1200cc oil" and at the base of the cylinder it says "351CC".  On the carb, it also says "Japan" and "ISO" whatever that means.  Also thank you for the info on the O-ring and main jet.  Does it  matter if the jet is hex or round?  Pat

That's an early spigot carb so number is likely stamped on the front of the carb just under the starter lever.  You might not be able to see it with carb on the bike.

Yes, round and hex mains flow slightly different and have different threads so not interchangeable.  BUT round main threads into some early needle jets in place of jet setter.  (Hex main won't thread correctly into needle jet on those models.)  

VM 4/042 style jets 

You were right of course!  I'd forgotten that the choke is sometimes called "starter"...mine has "choke" printed on the lever.  I did eventually find the number just where you'd indicated under a patina of age after careful rubbing and having the light at just the right angle.  It says 44561 .  Also, thanks for steering me in on downloading the factory service manual.  I'm going to go with the jet setter with O-ring, needle at mid-position, and a 170 hex main jet since I'm at 5,000 feet.                
Any thoughts on replacing the reeds with the new polymer reeds?  They seem flimsy compared to OEM and the original looks fine to my untrained eye.  
Many thanks!  Pat

That's what I have...thank you Sir!

I would not install aftermarket reeds unless you needed to.  Boyesen reeds specifically give a neat improvement of off-idle throttle response but kill power in the testing I've done years ago.  Many people swear by them, I'm not one of them.  

Also do yourself a favor and read up on how the carburetor works before you go crazy on the jetting.  How far the throttle is open is KEY.   Main jet primarily affects 3/4 to full throttle opening.  Most normal riding is done at half throttle or less.  You need to give the engine what it needs (for example changing reeds often requires different jetting) and adjust the correct circuit in carburetor for the throttle opening (not "RPM"!!!) that is too rich or too lean. 

Roger that Mark, thank you!  

I lost the tiny pin that prevents the main needle nozzle from turning...any suggestions?  A tiny screw perhaps?

Pat