I have two 1998 TS770 boats. New to me. Purchased not running, but otherwise in good shape. One was run with the injection pump removed but no oil in the fuel. I just installed an SBT engine into this one. I currently have the other apart due to some internal noises which turned out to be piston slap do to wear on original 17 year old engine. There was so much residual oil in this engine and exhaust system, I am pretty sure sure the previous owner put the premix in this boat and the raw gas in the boat with the injection pump removed. I am about to order a top end/cylinder kit and crank seals for it this one along with some other parts to get them both ready to go for summer.

I have read in the service manual that if you use Oxygenated gasoline you should bump the jets up one size or you will damage the engine.
I have also read that you are supposed to increase jet size when switching from oil injection to pre-mix. I am removing the oil pump so both boats will be the same.

The Question....

The dual MiKuni 38's currently have 57.5 low and 125 high jets. Can you suggest proper jets for this situation? Do I need to change both or just the High speed jet?