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  1. #1
    i will get all the rest i need when im dead corkycat's Avatar
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    Yamaha supercharged mods

    Just a brief thread to let anybody interested in the Yamaha sho jetski performance findings, I live in the UK and have found that some performance mods for the sho work well and some are not needed.


    My ski started life in standard form when I purchased it with 12hrs on it


    my first mod was the exhaust and air filter along with the intake manifold mod (ribbon removal) these mods are necessary for allowing the ski to breath better and also if you are modding any further are also a requirement I found that these mods let the ski breath a lot better and the throttle response was more clear

    next was the intercooler core this was a waste of money and I wish I had put the extra towards a bigger intercooler the flow rate through the standard intercooler is small when the ski is standard it is adequate but once you start to add on then this intercooler will soon become your weak link I saw no noticeable gain apart from shiny metal hidden inside a housing!!

    Next was the r&d water cooling kit, this may be needed in the us but is not needed in the UK, r&d recommend you remove the thermostat when fitting the kit...all this did was make the ski run rough as the engine never got warm, thus running rich all the time. I have re-fitted the thermostat the ski still runs very cold even after hammering the ski for long periods of time the temp of the cooling outlets is cold to the touch I am leaving this on though as it will help me when I take my ski abroad later in the year.


    I then added the powershot, in my honest opinion this is not needed in the UK for adding fuel as our water is so cold, the ski always seemed to be overfueling and even when switching it off it made no difference I inspected the plugs on several settings and the plug burn was fine and actually better once I removed it. After several tests I kept the powershot on as this was helping the boost limiter problem (has a built in boost override) but I can also increase a touch of fuel at different stages or decrease it where needed, again hardly noticeable in our cold climate
    I added the c3-11 supercharger wheel this gave me much more boost and power mid range and throttle response was much better, supercharger spool was increased and although there is a very slight lag when powering down it is next to nothing. This is one of the best mods to do in my op
    I also added the hks bov to protect the clutch this is a must as the boost increase is massive over stock, while installing the c3-11 wheel I also added the upgraded supercharger shaft from Riva, sat side by side next to my original shaft I could not see any difference in appearance or colour (I work in the oil industry and the difference in metals when they fatigue I.e. making them stronger metals you can usually see a slight colour difference ) suppose I will take their word for it.

    I had already added a 13/22 prop as one of my first jobs after adding the c3 I removed this and then added a 13/25 prop to get me off the rev limiter once I added the c3 but neither props would do this, I even got a 15/22 turned to a 17/27 from a well known guy on the greenhulk but again this still didn't get me out of the limiter although it wasn't far off! I had to bite the bullet and purchase the ecu remap from r&d this has worked a treat and have kept the 13/25 prop installed. As the 17/27 was far to steep


    Power delivery from standstill is similar what the ski was before as there is lots of cavitation because there is so much power going through the drive, once moving (roughly 10mph) and you nail the throttle the pull on your arms is like nothing I have experienced before it is difficult to hold on as you are ppppropelledom 0-60 in what seems like a second, mid speed riding is mainly the same as before with no nnnnoticeable uncomfort and no sudden unpredictable jolting as you go a touch faster, you get the same arm wrenching pull no matter what speed you are going when you nail the throttle, even at just off wot and you nail it there is a massive surge of power most of my riding is in choppyy waves (2ft sometimes 6-8ft) the ski before when wavejuming was no slouch but I found you had to nail the throttle and ride up the wave (as you do on any ski) now only half throttle is needed, and if you want to launch out of a wave then on ly a blip on the throttle is needed.
    In my opinion for rec riding all that is needed is the remap, the supercharger wheel, a decent true 13/25 prop and your usual handling mods. For the UK but this is my own personal opinion on the 5 months of constant tinkering I have done,
    Fuel economy on a full tank is greatly increased I am getting far more riding time now to a full tank than I was before with the same riding style..






    Please bear in mind this info is from my own personal findings and is by no means slatting anybody, im just being honest with my findings


    still to come, this week I am testing my ecu on a slightly modded sho to see what differences we get WITH A DIFFERENT PROP and I am also going to test my original prop 12/20 to see what gains, losses I get. I will post my findings


  2. #2
    JFizzleJR's Avatar
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    colder water will make the ski run leaner; therefore the powershot would be needed more, not less than in a warm climate. plug burn is not a good gauge of AFR on 4 strokes. you need a real AFR monitor for tuning these high HP/modified machines.

  3. #3
    Antiguan FZR's Avatar
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    Whats your top speed like with the Reflash, C3 and 13/25?

  4. #4
    hitman's Avatar
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    Quote Originally Posted by JFizzleJR View Post
    colder water will make the ski run leaner; therefore the powershot would be needed more, not less than in a warm climate. plug burn is not a good gauge of AFR on 4 strokes. you need a real AFR monitor for tuning these high HP/modified machines.
    100% agree

  5. #5
    RichieFZR's Avatar
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    Quote Originally Posted by hitman View Post
    100% agree
    +2 Agreed.

  6. #6
    Correct! colder water = colder/denser intake charge = needs more fuel.

  7. #7
    i will get all the rest i need when im dead corkycat's Avatar
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    Quote Originally Posted by JFizzleJR View Post
    colder water will make the ski run leaner; therefore the powershot would be needed more, not less than in a warm climate. plug burn is not a good gauge of AFR on 4 strokes. you need a real AFR monitor for tuning these high HP/modified machines.
    ooopps, i was thinking the other way round either way the powershot seems to do nothing as for afr im well aware of this and knew this would be one of the first points made, i was just using the plugs as a rough guide, a true afr guage is on its way. we are using 99 octane fuel over here

  8. #8
    i will get all the rest i need when im dead corkycat's Avatar
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    Quote Originally Posted by Antiguan RXP View Post
    Whats your top speed like with the Reflash, C3 and 13/25?
    we saw 1 good run at 81.7mph using garmin gps and an average of 76mph

  9. #9
    Addicted Member 5001craig's Avatar
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    Great thread and info Corky.

    Thanks!

    Oh, and I understand that cooler air needs more fuel but when the engine is running cool (upon startup/when in cool water/with more cooling supplies than stock), I thought the ECU compensated for this and richened things up a bunch???

  10. #10
    RichieFZR's Avatar
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    Cold air and 99RON I would lean more of the fuel out , there is just power sitting there! Thats just me....lol

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