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Thread: 500 RMK Help MPG

  1. #1
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    Default 500 RMK Help MPG

    OK I've been beating my brains out on this sled all winter

    cleaned the carb, new floats, rebuilt the fuel pump rejetted.........now that plugs are CLEAN but I'm still getting 4MPG on mellow trail riding.....

    I keep thinking there MUST be a leack but I can't figure out where the gas is going (especially now that the plugs are clean and look good!!) and I don't see or SMELL leaking gas????

    somebody said track tension or clutch adjustment????????

    could this really knock me down to 4-5 MPG??

    The sled seems to run fine.........I've had it going 85 MPH on a lake

    seems peppy but I'm afraid to go on a lengthy trip .....ran out of gas once already (47 miles to the 11 gallon tank)

  2. #2
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    Default 4mpgs

    im not an expert by any means although i can fix almost anything, it would seem that if your engine is running good, and everything is working properly, you may look at the clutch. may be slipping excessively. i went riding with a friend and he had an older skidoo that the belt was slipping alot, the belt looked ok but the clutch was engaging at higher rpm, as engine speed stabalized the clutch just started letting go of the belt. after 20 miles the gas tank was more than half gone, had we a more experienced rider on it we may have known sooner that there was a problem. just an idea.

  3. #3

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    What year is this sled, also...which 500 is it? This could be a number of things.

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    Default it's a 2000.....

    thanks for the ideas....

    I'm digging into the clutch next

    it was initially hard to start and the plugs looked like crap so I was hoping that was the problem......

    on the plus side at least I'm learning a lot about my sled......

  5. #5

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    Pathfinder, you say your plugs looked bad. Your clutching may or may not be right, but clutching has zero impact on how your plugs look. If your plugs look bad, it is most likely a carburator problem, my guess would be it is too rich, as polaris is famous for letting their sleds go this way. If it runs good, and the plugs are a nice brown, then yes, clutching would be a good place to look. Also, someone above mentioned track tension. If this were way too tight it could affect gas mileage, although I have to run my track tight and I get great mileage for what I ride. I would look at the mains.

  6. #6
    Member MARV1's Avatar
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    Check your needle position, #3 is stock, #2 leans it out a bit from top. Fuel screw out1.25 turns, or even 1.
    The emphasis is on accuracy, not power!

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    Default Thanks for the out of season reply!!

    If anybody else sees this I never did get the problem fixed before the weather got warm and the snow disappeared.........

    Still sucking gas BIG time

    Seemed like when I took the carb apart (the last time) to check the float levels..........one side was FULL of gas the other side had a little bit

    I had already replaced both floats mid season $$$$$$$$$$$$

    Is there something else which would cause one bowl to "flood"?

    Yes we already checked the needles and the gas screw

  8. #8
    Moderator AKmud's Avatar
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    Default

    Sounds like you could have a leak in a gas line. If the engine is running OK it may be leaking out onto the snow when the engine is running and pumping gas through the lines. I had a 500 EFI SKS that would routinely get 130-140 miles out of a 10.2 gal tank. Heck, I get 100 miles out of my 700 RMK (also 10.2 gal) now when I run the trails and limit the powder runs.
    AKmud
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    The porcupine is a peacful animal yet God still thought it necessary to give him quills....

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    Default Ditto

    I know it seems like that must be the case but on the snow or running on the trailer or running in the driveway there's ZERO sign of a gas leak

    My son has a 700 RMK and while I'm on the trail (mostly) he's out there pounding the powder and putting probably 20% -30% more miles on his sled than I am......

    I use twice the gas he does......

    this is reminding me I also rebuilt the fuel pump, synched the carbs, checked the reeds.........

    also aligned the clutch and checked the track tension

    learning a lot about my sled but it STILL seems to be sucking a huge amount of gas

    if I'm remembering correctly when the season ended last year one plug was looking good and one was almost looking washed out by gas like it was getting so flooded it wasn't even firing

    that's when we noticed one carb bowl full of gas and the other one with a tablespoon or 2........

    all I can think to do is put on new spark plug wires and caps (make sure it's getting sufficient spark)

    and then maybe swap the floats and see check the plugs again.......

    I guess the good news is if I ever get this issue resolved I should have one FINE running mo-chine!

  10. #10
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    Default cdi

    Next unit to check is the cdi. Someone you might know may have the same sled you have to swap out the cdi and give that a try. On my Escape when it was new the cdi to a crap and was stuck in retard mode after overheating. It would run ok on the bottom end but had no topend speed or anything past 1/3 throttle. Your's may sound like it is running ok, but the ignition might be retarded(lol) and not be burning the fuel properly.
    And yes the needles and floats are one assembly. Dirt lodged in one will allow your bowls to fill with fuel. Good luck with it, think snow!
    The emphasis is on accuracy, not power!

  11. #11
    Moderator AKmud's Avatar
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    Default

    I've been thinking about this and I'm not sure how it could be an engine/carb problem if the engine is running ok. If the carbs are flooding, then the engine won't run worth crap. Even a clutching problem should be easy to find simply in machine performance. You said you got 80+ mph out of it which for a 500 is pretty good. If the clutching is so bad it is affecting the mileage, I would think you would notice a big performance problem either at low end or high (mid range clutch problems are rare). Your max RPM (ideal) should be about 7800-8000 depending on what spring/weight setup you have. Clutch engagement should be around 3800-4000.

    I'm still thinking there has to be a leak somewhere. Maybe it doesn't appear until the engine RPM is high and the fuel is under more pressure? You might try blocking the machine up and running the engine from mid range to full and back for a few minutes and see if a puddle develops somewhere. I'm having a hard time swallowing this being an engine/carb problem though.

    It's a good puzzle though
    AKmud
    http://i78.photobucket.com/albums/j96/AKmud/213700RMK1-1.jpg


    The porcupine is a peacful animal yet God still thought it necessary to give him quills....

  12. #12
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    Default yeah just what I need a puzzle!!!!!!!!!!!

    well the plugs DO look crappy..........especially one so I guess I can look there

    but you're right............4 MPG is just a butt load of gas pouring through there

    I've never EVER had a sniff of gas and I did stop and check a lot but that's a good idea to maybe block it up and check it a little........

    one thing that happens is when I sit on the sled the tank "wheezes"...........which my sons RMK does not

    I don't see any gas leaking anywhere but when you sit on the seat or move around on it there is definitely air "whooshing" out the top............

    if I ever figure out what it is I'll post it here

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