Ultra 250 IMPROS IMPELLER TESTING
As some of you may know........I have been testing 2 Impellers for the Ultra 250X. A modified OEM unit and a Sea-Doo RXP IMPELLER on a Kawasaki Hub.

I have been testing them since early summer. I have sent the props back and forth acrosss the country testing one while the other was in shipment getting inspected, repitched, and returned. Recording data and testing almost daily. This information has been a long time coming. But I recorded eveything myself, good and bad.

Final testing temp was 72. Humidity 65%

Oem stock ski......63.4 mph......7500-7550 rpm
Ram Air modification that works!
LX Pump wedge 64.3 mph at 7500-7550
Riva ride plate with LX wedge 66.6 mph at 7550-7600
Intake Grate Center bar removed 67.1.
HOLESHOT WAS GREATLY IMPROVED/VERY QUICK OFF THE LINE
IMPROS OEM MODIFIED-PRO-SERIES-CUT-MOD/PITCH......68.4 mph at 7850-7900 rpm.
wet pump modification 7900-7950 69.1 MPH
My engine is completely 100% stock. No intake and no exhaust modifications I do have a mechanical boost guage on the hood........it reads right on 11.5 psi at full throttle.

The work and time we have spent doing R and D testing on these impellers has now paid off. I have documented all of this on the same day from 11/20/07. The best way I could be sure it was fair with FULL tank of fuel on the ski. Never had a chance to run the unit with low fuel..............too much wrenching going on.

As noted above the IMPROS modified stock gave me a 1.3 mph increase in top speed and kept the rpms right were I need them. 7850-7900. With cooler air and lower humidity I feel that I can scratch the 70 mph club.

Dave Stewart asked me not to disclosed the impeller pitch on my unit as we have changed it several times.
Also Dave also stated that the impeller trailing edge has a different cut that improves flow through the pump that makes it more efficient. It actually flows close to the same amout of water with less blade area and less drag on the engine and drivetrain.


The modification for the ULTRA 250 OEM Impeller is 125.00 and you pay shipping back and forth. I also had to pay an addtional 25.00 to have the impeller welded and trued and spun balanced.

MANY OF THE ULTRA 250 IMPELLERS ARE HITTING OR/SCRAPING THE HOUSINGS. THE IMPELLER YOU SEND IN COULD REQUIRE OUTSIE DIAMETER WELDING AND SIZING. "MINE DID" . THE BEST CLEARANCE WE FOUND WORKED THE BEST WAS .07 ON EACH SIDE OF THE IMPELLER. iF YOU LOOK IN YOUR PUMP HOUSING FROM UNDERNEATH AND THERE ARE DARK SPOTS IN YOU WEAR RING AREA.......THE REAR PUMP BEARING IS OUT AND THE IMPELLER IS WORN ON THE OUTSIE EDGE AND NEEDS SERVICE. TO WORK PROPERLY.

OK WHILE YOUR IMPELLER IS OUT TO GET THE Impros Super Tune U250 mod cut. Which is only about a 3 day turnaround this time of year. Lets MOd you pump with a WET BEARING SET-UP!

WET BEARING SET-UP Sooooooooo EASY!!!

1.0 remove pump assy with nozzle.
2.0 remove tail cone from pump. "twist off"
3.0 Place pump shart in a vice or use the OEM tool.
4.0 remove impeller and lay aside.
5.0 inspect rear pump housing for water droplets of moisture in the pump cavity by looking in the cone area with a flash light.
6.0 If pump is dry you are good to go. The seals are working well. If not new seals are a brezze to install.
7.0 now the modification:
8.0 using a long sharp pic, remove the innner dust seal on the insde of the pump housing and if you are going to use a new bearing "which the new bearings being very easy to install I reccomend it . The bearings can be removed and installed in just minutes. Remember only the inside dust shield on the bearing in the front. Remove BOTH dust sheilds for the "new bearing you just installed in the rear for 13.50. Plus about $8-10 for the Gear-Oil . an that is all of the cost to get free power.

DO THIS MODIFICATION AND DO A BEFORE AFTER TEST WITH A FEW PEOPLE AND SEE WHAT THEY THINK.......30% OR MORE LESS DRAG!

HURRICANE 1000
9.0 At this point you need to put a heavy coat of grease around the o ring on the pump shaft so no damage happens to the o ring during installation.
10.0 Turn the pump upside down and put your finger in the impeller side on the bottom where the stainless sleeves protrude out of the cavity that the impeller shaft uses. keep oil from coming out.
11.0 Only use BEL RAY GEAR SAVER 80/90 WT/OIL
trust me on this oil. When we replace the fingerfull of grease in those pump bearings with oil that is thin but rated excellent. 80/90 weight.
12.0 Fill the pump housing full of the BELL RAY Gear Saver oil all the way to the top.
14.0 The pump shaft should be installed with the new bearing pressed on the shaft.
13.0 While the pump is full of oil install the pump shaft pushing down toward your finger sealing the bottom.
The pump shaft will push into place and the 3 oil seals we checked earlier will seal the shaft so no leaks.
14.0 However, there wil be some oil leaking our because our purpose is to fill the cavity to nearly 90%.
15.0 Install the rear cone and o ring and you are in business!


THE RESULTS ARE FANTASTIC!....30% LESS DRAG ON YOUR IMPELLER TURING IN THE PUMP HOUSING WITH THE OIL IN THERE INSTEAD OF THE GREASE.

JUST REMEMER REMOVE TWO SEALS AND FILL HER UP WITH THE BEL RAY GEARSAVER 80/9O WEIGHT. IT IS THIN AND LOOKS LIKE TRANSMISSION OIL. LESS PUMP/IMPELLER drag more power to the water..........

12.0 Install the pump shaft slowly and when you feel pressure just give it a good quick push it will go right in there and the o ring will be sealed. You will spill just a few drops of oil as the sharf pushes throgh.

13. Reinstall pump shaft assembly in the vice and install the new reworked impeller andtorque to 72 ft lbs and remove from vice .........as there will be a few drops of oil again...........

14. reinstall the pump cone and then reinstall the pump assembly being very carfull to clean the rubber seal with soap and water, as it usually has so much grease on the seal it causes cavitaion. Clean them really well and clean the inside of the pump are where the pump seals against the hull with brake cleaner. Wipe dry....important.

15.0 Then spray the inside of the pump cavity and the outside rubber seal on the pump with windex heavily and the pump will slide right in as long as you get the splines lines up. You are good to go.
That is the best tip I have ever had that worked REALLY GREAT!

Give Dave Stewart a call at IMPROS for more information at 909-370-4900

The ULTRA 250 Mod is 125.00.
Welding if needed .......25.00.

150.00 worst case . 1.4 mph for my ski.....Runs Great.

Then picked up .5 with the wet/pump modification that is almost free!

See Above1

My final conclusion 1.4 mph worth the money.
Third best mph gain for your money.

Hurricane 1000.................

If you have any questions fell freee to send a message I will respond.