1000J jetting: 1983 vs 1981/82

Currently restoring a 1983 KZ1000J3 and I checked the jetting in parts diagram. MJ are written to be 117.5 while 1981/92 have 127.5. PJ are 37.5 for all 1981/82/83.

Anyone knows why a drop of 10 on MJ for 1983?? Looks like a major step down to me.

Airbox is the same and while LH & RH mufflers do not have the same p/n between 1983 and 1981/82, I'm skeptical as why they would require a 10 drop on MJ.

Thanks!

Jet needles and needle jets are also different.

Agree with Texas that the needle and needle jet differences can be the cause in main jet differences.  I do not know this as fact but it could also be there are differences between the air jets for the needle/neelde jet/main jet between the years.

Thanks for your comments!
I found the original MJ of my J3; they were in the jet kit box I got in the parts coming with the bike when I bought it. And they indeed were 117.5.
I will install back the original needles (also in the jet kit box) and will start tuning with the OEM jetting.
The jet kit is Dynajet and the PO installed the largest MJ (138 DJ) supplied in the kit... Looks like he did not had time to ride the bike with such a jetting as they are still brand new unstained brass.