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  1. #1
    PWCToday Regular thetmaxx's Avatar
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    Jun 2011
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    Reviving a 650 in a Waverunner III

    I bought this Wr3 for 240$. knew it wouldn't run, no battery, etc.. Cleaned all the start/stop contacts, got it cranking. has 3 gallons bad fuel. filled her up with good fuel (premix, because auto lube has been removed 50:1) still wont fire off. Spark looked super weak, so I did some voltage tests as per a Yamaha tech, and looks like a bad coil. replace coil, still fairly weak spark But it did run, although very rough,

    Check compression, got 25/145psi. WHOA!! problem solved. Found a broken ring. ordered std pistons and honed the cylinders. Now I had 140/145PSI.

    Today was the first time on the water. Idled good, ran it easy for a half hour or so. then slowly opened up to WOT, running good but I don't know much about 2 stroke so I was scared it would lean out and burn up... I also reset Carb settings to what is in the factory Yamaha manual.. something like 1.5 High speed, and 1 turn out on low speed.

    So I tried to richen it a bit to see if it would run better/ worse... No change, but it wouldn't idle, like it was loading up. so my buddy talks me into richer on the low speed, no go... way worse. so back to factory spec and now it feels like the over temp sensor is kicking in... lots of hesitation/missfiring check all of the water flow, and the engine isn't even that hot to the touch, ruled that out.

    Then I thought it felt like it was running on one cylinder and the other is just kicking in and out monetarily. So took it home, and 130/135 psi is my compression. looks like it dropped a bit after breaking in, but still pretty good i thought...

    removed the plugs, and they are very dark brown on the ceramic part inside the spark plug. also lots of black carbon build up for as short of a time as i rode it. Now I'm thinking it was too rich, and fouled the plugs??? cleaned them and it seems to run better, but this is no load so it's really hard to tell.

    I was getting some blue smoke at trolling speed if that helps. Any input about anything? I was trying to get it set for camping, and I'm thinking I just need to bring some new plugs (a few sets) and lean it out a bit?
    Last edited by thetmaxx; 07-04-2011 at 03:59 PM.
    93 Yamaha Waverunner 500 (Quadra Fin Ride Plate, Pro-tec Intake Grate, Solas 13/18 Impeller, Jetlyne Waterbox, Ocean Pro Vortex Flame Arrestor, Pro-tec Jet Nozzle)
    94 Yamaha Waverunner 3 650 (Quadrafin Ride Plate, Westcoast Intake Grate, Solas Impeller, Ocean Pro Vortex Flame Arrestor, Pro-tec 1/2 Pipe, Westcoast 28cc Head)

  2. #2
    PWCToday.com Is My Home Away From Home ZMANN's Avatar
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    Re: Reviving a 650 in a Waverunner III

    you never opened and inspected the carb?
    http://www.pwctoday.com/image.php?type=sigpic&userid=15348&dateline=1238301767

  3. #3
    PWCToday Regular thetmaxx's Avatar
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    Re: Reviving a 650 in a Waverunner III

    Yes, I did open, and clean the jets and needle valves. as well as ensured all the rubber components were operational, cleaned pop off valve. Inspected the fuel pump side, looks very good however I did not see the fuel filter in there, and did not know of its existance until i was browsing the service manual yesterday. But I believe the carb is all clean.
    93 Yamaha Waverunner 500 (Quadra Fin Ride Plate, Pro-tec Intake Grate, Solas 13/18 Impeller, Jetlyne Waterbox, Ocean Pro Vortex Flame Arrestor, Pro-tec Jet Nozzle)
    94 Yamaha Waverunner 3 650 (Quadrafin Ride Plate, Westcoast Intake Grate, Solas Impeller, Ocean Pro Vortex Flame Arrestor, Pro-tec 1/2 Pipe, Westcoast 28cc Head)

  4. #4
    I dream skis jonny72888's Avatar
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    Aug 2010
    Location
    Mass
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    Re: Reviving a 650 in a Waverunner III

    I run mine at almost 1/2 turn lean from stock. I have a water box, reeds, and msd. I found that stock was holding it back.
    '85 550js (sold)
    '87 650sx
    '95 SeaDoo SP 580
    solas x
    '90 WaveRunner III (sold)
    Msd enhancer,Boyesen reeds,Solas 14.7/18.5
    '92 550sx (sold)
    210psi, .5mm overbore, SBT crank, cdk2 40, Factory half pipe, Boyesen reeds, West coast box, Solas 13/18, Blue printed and Bored pump, PJS toploader, Dual cooling, Foot holds, , Ocean pro rideplate, Blowsion tornado, Flow control valve, MSD TL
    '87 300sx (sold)
    Flatdeck,650 pump w/trim, 750 big pin.
    '96 SeaDoo XP 800
    Solas X, Top loader, blowsion tornados

  5. #5

    Re: Reviving a 650 in a Waverunner III

    While it's not correct, I never send anyone off without a box of plugs and wrench. 2 strokes tend to eat plugs for breakfast, and I tend to let them go a couple of sets of plugs before I get too worried about changing anything, especially if it's been sitting around a while. Sometimes bad gas and evil spirits go away after a couple of tanks and a couple of plug changes.

    Without a popoff tester, it's hard to know if the needles & seats are actually OK, or if they just look OK. I have a real mistrust of needles & seats that have been sitting around... but that's probably just me.

    If the plugs consistently get dark fast, and it smooths out with a plug change, then I'd start pulling the screws in a little.
    Alan Kroeper
    EJF Engineering/jetsurf-r.com

  6. #6
    PWCToday Regular thetmaxx's Avatar
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    Re: Reviving a 650 in a Waverunner III

    So does dark plugs indicate that it is rich enough? Thats kind of what I gathered from the Mikuni manual anyways. I think I will be taking more plugs and leaning it out if so, I appreciate the feedback and confirmation that It might be ok after a while.
    93 Yamaha Waverunner 500 (Quadra Fin Ride Plate, Pro-tec Intake Grate, Solas 13/18 Impeller, Jetlyne Waterbox, Ocean Pro Vortex Flame Arrestor, Pro-tec Jet Nozzle)
    94 Yamaha Waverunner 3 650 (Quadrafin Ride Plate, Westcoast Intake Grate, Solas Impeller, Ocean Pro Vortex Flame Arrestor, Pro-tec 1/2 Pipe, Westcoast 28cc Head)

  7. #7

    Re: Reviving a 650 in a Waverunner III

    In general, the dark plugs indicate it's rich enough in the rpm range it was running most frequently. You can certainly have a boat that is lean on top and rich in the middle confuse the plug readings, so it's not a "written in stone" analysis, but pretty good.
    Alan Kroeper
    EJF Engineering/jetsurf-r.com

  8. #8
    PWCToday Regular thetmaxx's Avatar
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    Re: Reviving a 650 in a Waverunner III

    Thank you guys so much!! I normally run @ sea level basically in Sacramento on the river, we took it camping @ 4900 ft, I leaned out the screws a bit and put a new set of NGK's in it. (I brought 4 sets as per old-man-on-couch recommendation) WOW!! it ran so good!! except the Pump is cavitating like crazy but I started a new thread for that rebuild.

    After a few hours of riding it with completely consistent performance and a thumbs up from SWMBO while riding next to her (LOL) the plugs had a brown color to the electrodes but the rest of the plug was much cleaner with no carbon build up.

    Now that I'm back to sea levelish I will probably have to richen it up a bit, but how do you guys determine going lean enough for good performance but backing it up a bit for long long longevity?
    93 Yamaha Waverunner 500 (Quadra Fin Ride Plate, Pro-tec Intake Grate, Solas 13/18 Impeller, Jetlyne Waterbox, Ocean Pro Vortex Flame Arrestor, Pro-tec Jet Nozzle)
    94 Yamaha Waverunner 3 650 (Quadrafin Ride Plate, Westcoast Intake Grate, Solas Impeller, Ocean Pro Vortex Flame Arrestor, Pro-tec 1/2 Pipe, Westcoast 28cc Head)

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