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  1. #1

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    RR ecu and props

    a couple of us in Ca have been messing with our Rxp's for a while and after about 3 month of various testings we have put together some info that might be beneficial for others if they are going to modify there rxps.

    mods include rr ecu, intercooler, thermostat, riva air intake, riva sc impeller, impros solas 14/19.5, stock,r&d,waterbox mod on one of the ski, and riva intake grates(though these changed gps speeds, they really didn't have as much effect on rpms). I also did some little extras that gave me some more rpms but doesn't really affect what I'm about to describe.

    during initial install we found the 3 biggest problem of the setup were riva impeller supplied with the wrong nut, intercooler plumbing kits were too short making it difficult to completely seal intake between sc to intercooler to throttle, and with plumbing kit, it was almost impossible to install stock exhaust hose from waterbox to outlet without having major kinks in the hose. since these issues have all been talked about alot and manufactures have since corrected or have solutions for the problems, I won't go into them but if you have any of these three problems, it will be almost impossible to get your ski to run the way it should.

    I've found this setup to be very sensitive to water temp, altitude and prop size.
    after initial install, we went to a local lake around 90 degrees,1600 ft , and water temp was in the high 60's. the ski would turn around 8100 (and getting from around 7800-8100 took around 3 seconds so in any conidition besides really calm waters, I only saw around 7800 since everytime it came unhooked, it would need a few secs to climb to 8100 . put stock prop back in came up to 8300 rpms.

    we than went to the river around 100 degrees, 700 ft, water temp high 50's. with stock prop, it was hitting the rev limiter. installed solas back in spinning at 8300-8350 with no midrange problem at all. in between each time I rode, I removed and checked stuff and figured I must have done something that fixed it.

    went back to the local lake around 2 weeks later, 95 degrees, 1600 ft, and water temp was now in the low 70's. with solas prop 8000 rpms max. did not try stock prop, figured rr ecu just doesn't like this lake. 8000 with a 14/19.5 will still give you some respectable speed and since everyone else is in the same condition, I figured just leave it alone.

    we than went to the river again (july 4th) , now around 110 degrees, 700 ft, water temp's are now around 64 degrees. solas prop, 8250-8350.

    went back to the local lake, 100 degrees, 1600 ft and water temps were now in the mid 70's. with solas prop 7650 max. I figured here we go again. nothing was changed between the last river trip and this local lake trip and this is on 2 different ski's. could 900 ft difference in elevation and water temp difference of around 10 degrees cause a 600 rpm difference? air quality is different but on our friends stock ski with just riva air intake , the rpm difference between the river and local lake was around 150 rpms. we have tried better gas(50/50 91 and 110) to eliminate chance of knock sensor retard and it made no difference. we did install stock ecu and picked up some rpms however we put the rr ecu back in as thats the setup I want to figure out. I have spoke to Mark, Glen,Dave(impros) and Nils about this. I think it all comes down to the prop. I have not retried stock prop at local lake and will this week based on all other testing, rpms should be back in the 8200-8300 range.(however it cavitates so bad out of the hole, it's not even worth riding) the concords are big props to begin with and it seems like the rr ecu just doesn't make power between 7650-8000 . I have also got a new concord 14/19 out of the box and will test that probably today. I have been using concords in my 2 strokes for years and have never had good luck with them being modified. I mean that the concords are good for speed and whenever they get touched, I get the rpms but lose alot of the speed that they are good for. I'm not knocking impro's as the ski runs good at the river but I think for the sake of testing, it would me much easier with an unmolested prop.if I can't get this ski to run good with that prop, I'll start messing with the nozzles and have one nozzle for the local lake and one for the river.

    I posted this because if I had just purchased this setup and only ride at the local lake, I would be pulling my hair out right now. 7650 would be the best rpms I see and I will have a post on here asking why my ski runs like shit with this setup. because I have seen it run good at the river, at least I know it's not the ski and no amount of wrenching and checking would have helped at the local lake except the prop and that would have been the last thing that crossed my mind especially when it runs decent with the stock ecu. if anyone is going to do one of these mods on there ski, I would highly recommend leaving the stock prop is in there and getting it to run good first as everyone's riding location is different and I have seen such a big difference in performance(600 rpms) from 2 different locations. once again all testing was done on 2 different ski's with similar results.

    Terry, I read your post. this applys to you alot. If you live in vegas, I'm assuming you ride Mead. try a stock prop if you have a chance or better yet, go to laughlin and try your ski out. I bet you pick up around 400 rpms.

    Mike


  2. #2
    Site Admin Green Hulk's Avatar
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    Thats great info Mike. I have seen people have so many problems when installing the RR setup because they get a Solas, have it pitched and expect everything to jive when the put everything together.

    I think the best thing you can do is leave the stock prop in place and then tune as needed from there.

  3. #3
    Moderator Franko's Avatar
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    Great info Mike. Unfortunately for me, the RR ECU is sensitive to some, yet undetermined variable other than the prop. I get 7650 RPM with every prop I've tried: stock, stock repitch, Solas Impros 14/20. But I'll keep looking.

  4. #4
    way2fast's Avatar
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    Mike; You posted a lot of info on water and air temp, elevation, RPM etc, but no GPS speed readings. Why? You can turn super high revs with one prop and yet be going a lot slower than with another one at lower RPM's Speed is not always determined by engine revolutions.


    Richard

  5. #5
    Quote Originally Posted by way2fast
    Mike; You posted a lot of info on water and air temp, elevation, RPM etc, but no GPS speed readings. Why? You can turn super high revs with one prop and yet be going a lot slower than with another one at lower RPM's Speed is not always determined by engine revolutions.


    Richard
    I tried something different yesterday. I have an '05 rxp with the riva stage 2 - the wedge and the solas 15/20 it came with. With that i only manage 7700 (didnt have gps for speed) at the most. The lake i ride at is at 2600 msl oat 95 and water temps between 83-85. I then put the stock prop on and turned about 8050 to occasional rev limiter at 71.5 at best.Does this sound normal. Would the rr ecu give me more power or is my ski a lemon.

  6. #6
    Quote Originally Posted by aviator921
    Quote Originally Posted by way2fast
    Mike; You posted a lot of info on water and air temp, elevation, RPM etc, but no GPS speed readings. Why? You can turn super high revs with one prop and yet be going a lot slower than with another one at lower RPM's Speed is not always determined by engine revolutions.


    Richard
    I tried something different yesterday. I have an '05 rxp with the riva stage 2 with the solas 15/20 it came with minus the wedge. With that i only manage 7700 (didnt have gps for speed) at the most. The lake i ride at is at 2600 msl oat 95 and water temps between 83-85. I then put the stock prop on and turned about 8050 to occasional rev limiter at 71.5 at best.Does this sound normal. Would the rr ecu give me more power or is my ski a lemon.

  7. #7

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    Richard, I didn't post speeds because I didn't want this thread to turn into any kind of bashing. 600 rpms loss with the same prop(solas 14/19.5 through a stock 82.9mm nozzle) caused around a 6 mph loss. because all good results came from the river(colorado) and current speeds there vary because the width of the river changes, it's very hard to post accurate speeds. but if I was to average it out running in both directions, I'm pretty comfortable to say in calm conditions it is over 75 while at the local lake it's around 69.

    Franko, did you ever intstall a boost gauge? also I doubt this is your problem but when you have a chance, take a look at the pump where it mounts to the pump shoe. do you see a yellow tab sticking out of the top rear left corner?

    Mike

  8. #8
    Quote Originally Posted by seadoo1120
    . do you see a yellow tab sticking out of the top rear left corner?

    Mike
    now wait a minute? are you missing your reducer? (the little yellow tab you were referring to). If you are, that may be some of the cause of your headache.

  9. #9
    Moderator Franko's Avatar
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    Mike, I will check that out tonight when I get home. But I know for sure it was there when I did my first prop change. It fell out and I had to put it back in. I guess it could have fallen out again.

  10. #10
    Moderator Franko's Avatar
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    Quote Originally Posted by seadoo1120
    Franko, did you ever intstall a boost gauge?
    Mike
    I have a boost gauge that I am installing when I put my engine back in. Any tips on hooking up the electrical?

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