YZ125H Carb Help: Mystery Pilot Jet

Hey guys how's it going. I have a little story to tell. The year was 1980 about a month before Christmas. The place was a Yamaha Dealer in West Palm Beach, Florida off of 45th street. My parents purchased a brand new 1981 YZ125H as my xmas present from the owner Ray. The price was $1,199.00, after tax, prep and paperwork we got it out the door for $1,347.94. I raced Florida Trail Riders and local motocross, use to come up against, D.Longwell, K.Keylon, D.Porter and a few other old schoolers in my day and quickly noticed the the factory H model has this frequent stutter before hitting the power band. After a few FTR Hare Scrambles and a few races at Stadium Motocross in WPB back in the day, I realized it had to be something with the way Yamaha set up the carburetor circuits.

So it's spring 1981, I bounce down to Ray's Yamaha shop for a top end kit and explained the stuttering issues and Ray smiled and said "Give me a minute, I'll be right back". He comes back to the counter and holds up a little brass pilot jet and say's "here, drop this in your water pumper and your troubles are over, free of charge." So I get home, dropped in this new pilot jet and BAM!!!! No more low end stutter when ya put the crack open the throttle, it was like a new machine. Even though this motor had ZERO low end when that power hit with the new carb setup, it was explosive and no more gig-gig-gig-RAAAAAAANT.

Anyway...

Moving forward 40 years later, I just purchased a pretty decent mid life crisis 81 H model last week for a grand to semi-restore it and sure as I remember to this day, this bike has that same stutter. I assumed right off the bat, this machine's fuel system is completely stock and was never diagnosed and updated with this wonder jet. So my question is, does anyone have any idea or remember what that pilot jet number might have been? I know this was a minor manufacturer issue that was not revised by Yamaha, so others had to be aware of it. Was hoping to avoid having to buy up all the pilot jets I can find for the Mikuni 34SS and try them all out till I get the right one. So I decided to ask on here to see if anyone remembers that Pilot Jet and if there is a part number someone can shoot me. Hoping someone can save me a few hours of test and tune. Thanks in advance...

-TFNG

P.S. is rob.boucher.547 still around? I know everyone and their mother must blow him up for YZ125H help and ideas over the years, however his thread is like 7 ears old, not sure I want to resurrect it...