I slept on this and came up with an accurate way to measure the ratios, please see below...

FYI - These tests were on my 2015 Grizz with only 300km so the belt is fairly new

2.40:1 - Stock Sheave with stock 21 gram weights
2.48:1 - Stock Sheave with stock 21 gram weights and with .5 mm shim
2.56:1 - Stock Sheave with stock 21 gram weights and with 1 mm shim
2.64:1 - Stock Sheave with stock 21 gram weights and with 1.5 mm shim

2.35:1 - Stock Sheave with Dr Pulley 18 gram weights
2.43:1 - Stock Sheave with Dr Pulley 18 gram weights and with .5 mm shim
2.50:1 - Stock Sheave with Dr Pulley 18 gram weights and with 1 mm shim
2.58:1 - Stock Sheave with Dr Pulley 18 gram weights and with 1.5 mm shim

2.69:1 - JBS Sheave with 18 gram Dr Pulley weights
2.77:1 - JBS Sheave with 18 gram Dr Pulley weights and with .5 mm shim
2.88:1 - JBS Sheave with 18 gram Dr Pulley weights and with 1 mm shim
3.05:1 - JBS Sheave with 18 gram Dr Pulley weights and with 1.5 mm shim

I installed two indicators, one the primary and the other on the secondary, gave it an additional 1/2 dozen turns to ensure belt was at its max in secondary, marked both starting points at indicators and measured the difference. The circumference of the primary sheave was measured to be 65.5cm +/- mm.

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Advantages of JBS:
- JBS machined sheave ratio is a tad bit better than 1.5mm shim mod on bottom end torque
- Machined channels improves or maintains top speed
- For 2016 Grizzly owners a .5mm shim can be installed safely (according to James) others installed a 1mm shim safety. Install at your own risk!
- For 2015 and prior, a .5mm shim can be added safety with the purchase of the 1XD Viking cage (according to James) or possibly a 1mm shim, others have filed the stock cage the required amount to achieve adequate clearance due to the shim install. Install at your own risk!
- Can be either grease or greaseless

James, Niki and his team are great people and have invested allot of time and money into this product, it is of excellent quality with awesome service.

Feed back welcomed and if you need any measurements while I have the cover off please let me know, thank you for reading!