High Altitude Sea Doo SP

Hi Guys, I own a 1992 Sea Doo SP, which I love, To give it some boost I have made several modifications. My Sea Doo has a Skat-Trak 15/20 impeller, Aftermarket head with 31cc domes, Westcoast pipe and waterbox, one mikuni 46mm carb, aftermarket flame arresters, an MSD rev limiter (7500 RPM), stock timing, stock cylinders, a top loader intake grate, and a modified rotory valve. I pre-mix 40:1 and use NGK spark plug BR8EV and92 octane gas. These mods were great at sea level, but now I run at 4,000 feet. The low end is extremely sluggish and I dont rev more than 5900 RPM full throttle. I tried to adjust the idle and low screws with a little success. Are my mods in sync with each other? What should be my idle RPM.
​Oscar

Oscar,
Your SP is suffering from a rich condition and loss of head compression. I would recommend changing the head compression domes to bump up compression aprox 40lbs and re-jetting the carbs for the altitude.
​Tech Talk