Slow RXP Riva Stage 2

[idizzy]

After alot of effort it appears my ski is running strong but slow. I am running a full stage 2 with riva block offs, skat 3 bearing pump, and ss wear ring. I am running 8100rpm's and my best numbers were 73 and change on an empty tank???? I should be over 75, whats wrong?

[meirvin]

I too just got a stage II and am running 73.5, how is your air installed, mine is normal postion if yours is I think we need to think about a way to get it up and into fresh air

[Water4fire]

What air temp? Those are good numbers if in a 95+ degree weather.

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[Green Hulk]

idizzy, are you porpoising?

[idizzy]

I was porpoising but I put a pair of riva pro block offs on and it stopped. My air is inside the hull. It was warm but I know it can do better. Friends of mine with similar or equal setups are doing much better.

[Green Hulk]

The unfortunate thing about our skis is no two are created equal. Variances in assembly such as pump shoe and ride plate angle play a huge role in how your ski performs.

This is why we see two skis with identical mods perform differently.

One thing you may want to check is to ensure your grate fits flush with your ride plate.

[Vern]

Are you spinning a box stock 15/20 impeller to 8100 rpms? With most Riva Stage 2 setups, with a 14/19 impeller, people are running 73 - 74. Those who are running the 15/20 impellers at or near 8100 rpms are usually getting 75 mph or better. Do what Jerry said ... put a straight edge on the bottom, make sure your intake grate and ride plate line up and don't hang down.

I have the same setup plus a modded waterbox (I don't think that adds speed) and a 15/20 (trailing edge pulled back 2 mm) with Skat nozzle and with the 82 mm ring (1mm less than my stock nozzle), I turn 8000 - 8050 rpms and run 75+ mph with a full tank and 76 mph with 1/2 tank or less. But I have the full stage 2 setup including the wedge - are you running the wedge?

[jawz]

Pull the leading edge of the impeller down(less pitch) THEN Add 1mm to the trailing edge . Your pulling in too much water to accellerate the velocity of the water.

[idizzy]

I am running the complete stage 2 including wedge. My prop was tweaked to hit 8100 by Howard. My pump/intake are not perfect. But they are close and sealed with right stuff. I am going to relook at my intake and try a larger ring to see if I am underpitched.

[Green Hornet]

Have you checked your impellor cone? If you have the green one, solas, they tend to come loose.