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Thread: SLX 1200 Speed?

  1. #1
    D007's Avatar
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    SLX 1200 Speed?

    Hey Everybody!

    Took out my slx today for the first time since i bought it in february, ran good, idled good... but top speed on the mfd was only 57 . Conditions were pretty good and very little chop. Put it back on the trailer and took out my 900 to see what that got for comparison purposes and it was running 61 on the mfd.

    I know that a properly running slx 1200 should be in the mid 60's+ on the dream-o-meter so i was just wondering if anybody had ideas of why it would be going so slow? It has the rd grate on it and i hear that can slow it down, but i didn't think it would be that much slower with that grate on. Carbs were rebuilt and set at factory specs, rpm range seemed good, and played with various trim levels, but it did porpoise a bit at higher speeds.

    Overall ran good with no problems just seemed slow compared to my 900 for top speed.
    Dont have a stock grate to try and im thinking that may be the problem, or the mfd is off, I know they're not accurate. I know its not a ski for choppy conditions so i might swap out with an OE grate and see what that gets.

    Any ideas, thoughts, or tunning tricks much appreciated


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Intake grates can also affect the displayed speed.

    Check speed on both watercraft using a GPS unit. GPS readings is the only reliable way to compare speeds.

    What RPM were you seeing at WOT? RPM is a better measure of engine health than speed display.

  3. #3
    urugol's Avatar
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    I lost 10mph going from a stock grate to a performance Solas grate on my 900 - yes 10mph less! If you don't have a spare stock grate lying around you could just switch them between the 900 and the 1200 and test the theory.

  4. #4
    Now this is an appropriate speed limit sign. dragon129's Avatar
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    Definitely don't worry about what that speedo tells you. I have something somewhere in the system that's not registering the full water pressure so mine shows it's going slow, but I had the GPS on it and it's fine.

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    casey67's Avatar
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    These work good, it will wrap around the handle bar pad.
    http://cgi.ebay.com/Garmin-Forerunne...item3f0a157d8e

    You should see 6700 rpm,that will determine what to check. My SLX with a slightly bent impeller did 59mph @ 6900 rpm. With a good impeller I saw 63.5 at 6700 rpm.
    With the R&D "650" grate ,My slx lost 1 mph.

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    D007's Avatar
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    Tried today with the swap of the grates and saw 63 on mfd @ 6540 rpm for a brief second, sorta choppy water though, rough ride. Conditions were about the same as the first time i rode it. Havent had a chance to get it on straight glass yet so hopefully its just the chop. Seemed to gain a little with the swap of grates but did seem squirley and unhooked alot tho higher up in speed compared to when the rd was on it. Only time it would hit 6700 is when it bounced up a little then went back down, when it got hooked back up it would go back down a little in rpms.

    What does it mean since im not getting into the 67 range? Pump looks mint so i dont think it has anything to do with the pump, out of tune on the carbs or somethin' maybee? Idles between 14-1500 rpms when just sitting in the water.

    Thanks, and I appreciate all the info anybody can give!

  7. #7
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    You will hardly ever reach max speed in choppy conditions. Especially on a 2 seat SL hull. They aren't the best hulls for rough conditions. (likes to porpoise) So you generally set the ski up for the conditions you NORMALLY ride on. It doesn't make much sense to set the ski up for top speed if you're never going or hardly ever going to reach it due to conditions. So you set it up for better acceleration and keeping the pump hooked up for the most speed possible for the rough conditions. Things like the extended ride plate, scoop type intake grate, sponsons, impeller, etc... That is why you'll read some guys will say their top speed was X "in race trim" because it's set up for rough conditions.

    If you're not reaching max RPM, you may have a carb adjustment problem, your impeller may be too tall of a pitch, your compression may be low, reeds may be bad, jet pump bearings are going bad, things like that.

    Start with a compression test and let us know what you get.

    Then check your piston wash and see if you're running lean or rich on any cyls and adjust your carbs accordingly.

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    D007's Avatar
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    I think im gonna set up the 900 for chop and the slx for glass, seems so far havent had any glassy conditions yet tho. I'm the only one that rides them so figured i'd set one up for each condition.

    Compression is 120-120-120, cant really see the whole piston thru the plug hole but looks sorta lean, not seeing much wash, but havent had the heads & domes off for a full look. Carbs are set at factory spec - 1 1/8 turn out. Really responsive and accels very nice.

    Maybee im just premature to the speculation its goin slow since i havent tested on straight glassy water yet. Just sorta thought it seemed slow in the chop when my 900 seemed to be going faster. MFD's do lie though, and I probably wouldn't be able to feel a 3 mph difference much. Looking into one of the gps units for the handlebars for some accuracy.

    Thanks for the replies, all the info is great!

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    D007's Avatar
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    Hey everybody, sorry for the long post in advance....

    Took out the ski today and still having problems getting the rpms up where they should be. Was only getting 6340rpm's on almost glass.

    Piston wash looks decent, little richer on the cen cylinder so i adjusted the mag and pto accordingly before i went out, they were set at the factory spec of 1 1/8 turn out before i rode it today. How long does it usually take to see a "wash" start to develop? few rides?

    Also, I noticed that the mag and cen cylinders were getting hotter than the pto, does this indicate anything? Poped off the cooling rail when i got home and nothing appeared clogged. wasnt overheating just noticed the difference after riding. Does one cylinder being cooler indicate anything in relation to how lean/rich a cylinder is? Ran it in the garage after it had cooled to warm it up and it felt the same as after i got off the water.

    Compression is still decent 120 across the board
    Pump/impeller appears good - factory impeller - thought maybee it was an aftermarket that was maybee to steep but looks to a stocker.
    Trimmed up the plug wires and getting good strong spark - new plugs also
    Gets up and accelerates excellent - just not getting up to the rpm range it should be
    Only time it goes past 6340rpms is when i hit a wake or turn and go over a wave I made and bring it out of the water a little

    If anybody has any ideas/tips on getting this thing tuned i would much appreciate any suggestions, or if anybody else with a stock 1200slx has what their carbs are set at just for comparison purposes, I know each ski is different though. its driving me crazy not being able to get it just right. Wasn't near this difficult to tune my 900 to its sweet spot which ran like crap when i first got it. maybee im overlooking something or it is something more in depth.

    Thanks

  10. #10
    Click avatar for tech links/info, donation request K447's Avatar
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    Have you gone through the cooling system to confirm all is correct?

    Plastic mesh screen in place in jet pump nozzle?

    Thermostat and pressure bypass present or removed?

    Original water bar or replacement?

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