ZXI Removed Oil Injection

I have a 1995 Kawasaki JS750 ZXI Jet Ski. The previous owner removed the oil injection system with Oil Pump Block Off Plate and mixed it the gas 40:1. I was wondering if it is worth it to put the oil pump back on? Or if it would be better for the machine. If not what is the best fuel ratio to run, and is there anything I should check to make sure the owner did everything right when he took off the oil system?Also, my machine doesn't seemed like it is as quick or fast as it should be. Is there anything else I should check, Like impeller or reeds.
Russ

Russ, Reasons for removing oil pump is that Oil pumps can fail and You are able to pre-mix to a precise measurement as different oils offer different mixtures. I usually go 40:1 with standard oil and 50:1 with Synthetic oils.
  I would definitely check the Kawasaki impeller for nicks in the blades and the gap between the Jet Ski impeller and pump housing. If they have any issues that could defiantly cause a speed issue. Your ski is pretty old and I would recommend putting in some new reeds. I would do a head compression check and make sure all three cylinders are within 5lbs of each other. If they are more then 10psi between them you will need to do a rebuild top end piston kit.
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