From Isky web site:

http://www.iskycams.com/springbook.pdf

125 at 1.900"
145 at 1.850"
So at 1.88" that would be about 133 lbs seat

And at 0.590" lift from 1.88, ie 1.29" open
365 at 1.300"
385 at 1.250"
So at 1.29" that would be about 361 lbs open