Sprocket Fit and Dimensions Confusion

[Scottusa]

I have a Mini Baja which I understand like the Coleman products use different size bolt holes in their sprockets and they may also have
different size bore holes as well. It might even be that they are metric vs the USA SAE measurements but I am not sure.
View attachment 247756

View attachment 247756 The major internet vendors dont do very well explaining what sprockets they are sell fit what minibikes
and which size chains they are designed for or at least tolerate. All it would take is a few diagrams with dimensions shown to clear it all up
but darn if I can find them. Take a look at the following image I pulled from one of the vendors websites. Clearly stamped is a size and then
the marked dimensions do not equal the stamped measurement.

 

[Scottusa]

 

[danford1]

The 2-1/8" means it has a 2 1/8" hole in it. It takes a 420 chain and has 60 teeth and has 2 different bolt patterns.
The numbers in yellow are a reference for you to use to figure out if it fit your bike.

 

[Scottusa]

So far, I have seen from two vendor websites that MiniBaha and Coleman adult size mini bikes have the following large sprocket measurements

4 holes 3/8"
3.150" Bolt Circle (straight across)
1.580" Center hole ( a little more than one and a half inches )

OldMiniBikes says Mini Baja and Coleman sprockets require
Center hole diameter: 40mm [1.56"]
Mounting holes: 57mm [2.23"] center to center [side by side] (same as 2 1/4” )
Mounting holes distance: 80mm [3.15"] straight across

So for the sprocket illustrated above, it appears that the center hole is much larger than 1.5 inches amd is not compatible with MiniBaja