Just rebuilt my scrambler 400 4x4, and I did a compression test I get 140 psi. That seems high to me. Should I be running high octane in this machine. Or is this okay with 87 octane? I always thought that 125 psi was stock. Any advice thanks.

 

You should be ok with that on a newly rebuilt engine. I think stock is around 135, the minumum is 115, so I would say you are in good shape. If you didn't do any mods or running higher than factory compression ratio's, you don't need higher octane fuel.