I have installed the Riva stage 1 kit plus the vortech gen I SC Impeller w/ blowoff valve two years ago, and i was beating the RXT-X models all summer last year.

I just ordered the Gen II impeller, OPAS pro-series block off kit, SS wear ring, steel washers, Riva thermostat kit and the pro series reduction nozzle last week. With these mods installed I have a few tech questions:

What kind of performance changes might I expect; such as out of the hole, mid and/or top end?

Is the impeller I have (SRX-CD-14/17R) adequate for the applications that i have and will soon install?

I have the older style Riva Supercharger Blow-off Valve Kit; should I also have the newer style you have or is the older one basically the same?

What kind of performance changes would i see in addition to any from the above MODS if I also added the Riva water box and rear exhaust kit?

Lots of questions, I know.

Thanks in advance.

Chuck H.

nce whats your top speed

Garmin GPSput me at 71.5 mph last June/July. Later on in the summer when air and water temps were up i lost about 2 MPH and dropped from 8100 rpm down to 7850 - 7900 rpm.

I am hoping with addition of these other mods i ordered I can squeeze out a little more in the low - mid range. The RXT-X's were getting the early jump on me last year out of the hole but as soon as I planed off I really walked past them.

My top speed last year was 70.5, not as I previously posted as 71.5. sorry for the bad info. RPM infor was correct. I should re-read before I hit send.

70+ is great for a Stage I RXT! Our Supercharger Impellers do more for bottom-end and mid range acceleration.

Typically we've found that when installing our GEN-2 SC Impeller you need to go up in pitch on the pump impeller. Even when adding the Pro-Series Nozzle. One nice thing is you will be able to dial in your rpm using the interchangeable nozzle rings.

The Pro-Series OPAS Block-off's, SS Wear Ring and Thermostat Kit won't affect your prop selection. The Block-off's will improve handling. The SS Wear Ring will improve acceleration through reduced cavitation. And the Thermostat Kit will help prevent heat fade which will help keep your speed numbers up as it gets hotter out.

Our Rear Exhaust Kit and Pro-Series Water Box help with acceleration primarily. Plus they make the craft sound a lot better (throatier, but not annoying).

All of the engine mods you're adding will help significantly with acceleration. You should see some benefit in top speed as well. You may continue to run the Performance Blow-off Valve Kit up through Stage II. If you upgrade to Stage III you will then need to upgrade to the Pro-Series Blow-off Valve.

RIVA:

Thanks for the reply. I just got off of the phone with your parts department and ordered the power cooler, rear exhaust kit and the impeller for the stage II kit along with the other parts I ordered the other day. I'll bypass the water box purchase and save that for next season.

With all of the new upgrades I'm going to try and give the X and IC models hell on the water this year.

Thanks Again... I'll keep anyone interested in speeds, etc. as I get the parts on run it.

Chuck H.

I had the Stage II kit along with the Riva Thermostat, SS Wear Ring, Pro Series Nozzle kit and Pro Series Block off kit installed at a Sea Doo dealer last week. Dropped Ski in the water yesterday; 75 degree air temp, 63 degree water temp, light wind, full tank of fresh 91 octane and a 160 lb rider; I could only turn 7800 RPM and acheive 68.5 MPH on GPS. My Ski ran faster with my previous Stage I + set up.

Obviously there is a problem, I'm just not sure what it could be. I have new plugs, the Riva clutch washers and had the Sea Doo dealer check the clutch slippage when the Stage II kit was being installed. Last year in salt water (June)I was turning 8050 RPM and clocked at 70.5 MPH,later on in July, in fresh water I had dropped to about 7800 RPM and about 68 mph. I assumed the drop off in both RPM and speed were caused by the higher air and water temps.

Sorry for the long story.... I guess in a nutshell I'm looking for some suggestions. After spending $3800 in parts and labor I am a bit dismayed as what to do or where to look for answers.

Check all the hoses coming off the supercharger for loose connections, you may have a boost leak..

How many hours on the clutch/shaft assembly of the supercharger, at 100 hrs it is recommended to replace (not just change the washers).

I wouldn't recommend trusting the dealers for supercharger maintenance!!!

I have 53 hours on the ski.

I've spent all week looking everything over; there doesn't appear to be any boost loss/leak that I can find, the BOV seems to be functioning properly, I looked up into the grate for signs of a mis-aligned seal (none seen), checked the new plugs for signs of fouling (none), adjusted throttle cable and made sure oil level was within the proper range.

Dropped ski in water today and same result as last week; RPM's ranged from 7760 - 7820 max, speed 68.1 MPH.

Any suggestions as to what to do next? I went from a Stage 1+ to a Stage II+ and now i'm turning less RPM and less speed than before the upgrade.

The ski is an 06 RXT with 53 hours, serviced regularly and stored inside when not in use. As I stated in an earlier post, i had the heavy duty SC washers installed with the Stage II kit.

What am I missing?

Thanks

What pump impeller did you end up going with? As I stated in my previous post you will need to go up in pitch on the pump impeller to take advantage of the new mods. The Pro-Series Reduction Nozzle alone won't be enough.

I went with the one that comes with the stage II kit, ultimately that what i have installed.

OK, maybe we have overlooked the obvious, what size nozzle ring are you running? If your not already running the 83mm it may be worth a shot!!!!

I started with the 83mm ring. I chaned to the 82mm and then put my stock nozzle on just because i was out of ideas. I've never been more at a loss. I just ordered a re-build kit for the SC and will install this week.

What king of plugs are you running? I got some Iridian <sp> plugs from Riva last month.

OK... the story continues. Spent the money and bought the SC rebuild kit, had the SC rebuilt at a nearest Sea Doo dealer. Dropped ski in water and RPM's were 7680 and speed was 67.3. WTF is going on? This is getting worse not better. Suggestions? I'm now $4,300 into this stage II modification (parts and labor).


Thanks

Please call our tech rep at 954-247-0705. Explain everything to him. He's good at asking the right questions. A lot of times it's easier to figure out what's going on when discussing it verbally vs. posting back and forth online.

UPDATE:

If you've been following this thread you basically can see the problems I have been having, or thought I was having.

Back to the beginning....

Last year i was running 6080 rpm in salt water on the east coast, speed was 70.5 on GPS with a stage I kit.

Dropped skin in fresh water in mid-west (kansas) end of last summer rpm was 7800, speed 67 - 68. Thought it was time to change S/C clutch washers, oil, plugs etc.

Dropped in the stage II kit plus thermostat, SS wear ring and pro series block off. Dropped skin in the same mid-west Kansas lake a month ago, rpm was 7600 - 7700, speed 67.

During the last month I gave been going nuts checking and double checking everything looking for the reason I cannot get to the rpm/speeed listed for the stage II kit.... no luck. Spent an additional $500 on parts/labor for a supercharger rebuild thinking this was the problem.... after rebuild, no change. Total frustration at this point.

Sorry for the history, but it's relevant and maybe helpful to some of you.

It's 4th of July weekend and I'm taking the ski back to the east coast for my annual race week. At this point I'm sure the ski is not running up to par.... and im going to get my ass kicked by the x boats this year.

Drop in water today (salt water, same as place last year) and absolutley take off like a rocket... acceleration is un - freakin real, rpm 8060 and speed (on garmin GPS) is 73 MPH! Holy crap..... I kid you not, I pounded the crap out of an rxt-X.

The only things I can see that are a difference between mid-west and here are: salt water versus fresh and elevation.... elevation is Kansas 1350 feet, elevation here 0.

I would have never guessed..

Any comments on this phenomenon? I am truly shocked at the difference in this ski and the performance...

That's why I suggested you contact our tech rep. That one little detail (altitude) was overlooked by all of us and it plays a major part in how your craft will perform. Everything from how the engine runs to impeller pitch.

Glad to hear it's sorted out and your craft is running up to par. Thank you for posting the follow up. Hopefully someone with a similar problem will find this and it will help them out.