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  1. #1
    Newbie
    My Bike(s)
    2003 Rm 250
    Location
    Hillmond
    Posts
    3

    Exclamation 03 RM bogging at mid-high revs

    I purchased a 03 rm 250 last summer and thought i could fix the problem of it bogging out at mid-high revs, i was wrong any help would be greatly appreciated!

    Alredy cleaned carb ,rebuilt top end , new stator coils, good gas, dont know what else to do.

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  3. #2
    Clunked into first gear
    My Bike(s)
    2000 yz125 race prepped
    Location
    bentonville, arkansas, us
    Posts
    230
    whats the spark plug look like?
    I'm guessing it is black and kinda wet

    first set your float
    if it still bogs
    try raising the clip on the jet needle to fix the mid-range
    go to a smaller main jet for the high-rpm bogging

    keep watching your sparkplug, if it comes out white you have gone too lean, it should be a tannish mocha color

  4. #3
    Found second gear by accident
    My Bike(s)
    I'm lucky, I've got alot
    Location
    minnesota
    Posts
    328
    I'm thinking jetting or carb adjustments, from your posts that's all that's left.

    MOTO GUZZI

    loud valves save lives


  5. #4
    Newbie
    My Bike(s)
    2003 Rm 250
    Location
    Hillmond
    Posts
    3
    Thanks for the imput ill try that right now

  6. #5
    Special/Abusive Title
    Posts
    1,313
    imput?...............nah im just messin

  7. #6
    Newbie
    My Bike(s)
    1980 RM 125
    Location
    Crystal River, FL. good ol' USA
    Posts
    16
    yeah, carb tunning/jets. Look for a maintenance book for you bike...always a good investment. you can practically build a bike from my Clymer manual. best of luck. thats an awesome bike!

  8. #7
    Newbie
    My Bike(s)
    2003 Rm 250
    Location
    Hillmond
    Posts
    3
    before i buy a new main jet woudnt it run good on factory settings?

    because its at factory and im thinking its not the carb because i ajusted the clip on the jet needle and didnt see too much improvement.

  9. #8
    Clunked into first gear
    My Bike(s)
    2000 yz125 race prepped
    Location
    bentonville, arkansas, us
    Posts
    230
    from the factory, bikes are jetted for sea level, and usually safely rich. its not very likely a bike will come jetted perfectly from the factory-there is usually much to gain in properly jetting even a stock bike

    there are so many factors that effect your jetting that it makes it a big suspect for your bogging, especially considering what you already replaced-top end, stator coil -and i assume since you did those you also have a clean air filter and correct sparkplug

    at this point, if it were my bike, i would return the clip and ride it around using only half throttle, if it runs good and doesn't foul the plug, leave the jet needle alone (now i'm guessing the bog is more in the higher revs, if not let me know). Is the sparkplug black, wet, or sooty? do you have spooge coming out the silencer? if so, the bike is too rich, go down one size at a time on the main jet-they run about 5 bucks each
    if the plug is white or looks burnt-that is a lean condition-which can cause bogs but also has a sound you would probably recognize - known as pinging. check your plug-what does it look like?

    jetting is very trial and error- do remember though, that a rich bike will only foul plugs, but a lean bike will detonate-which is why i always go down one size jet at a time
    Last edited by the_privateer; 05-17-2007 at 11:59 PM.

  10. #9
    Seat Tester
    My Bike(s)
    2008 YZ450
    Location
    NOVA SCOTIA
    Posts
    70
    I have to jump in here. I have the same bike, and the jetting from factory is way off. Bogging at mid-high reves I assume that means half to full throttle or there about. Do you know what number the main jet is? While you have the carb bowl off check the float height-turn the carb upside down, the floats should stop the flow of fuel when they are parallel to the flat of the carb where the bowl mounts. I think the measurement is 6.5mm(+-1mm).Also check the float jet. But before you do all of this, on the left side of the cylinder there is a dial that is held in place by 2-8mm bolts. This is a pre load for the powervalve. If you back the bolts off the dial should be horizontal when there is no preload on the spring, to a half turn clockwise. Will the bike go in the powerband at all? Here is what my 2003 rm250 is jetted at

    pilot jet is a 42, main jet is a 162, stock needle at second clip down. I run 50:1 mix w/motule 800, and I mix my supreme gas(which is only 91 octane here) with 25% race fuel.(so 20 liters of fuel is 15l of super and 5l of race fuel).

    Let me know how you make out.

  11. #10
    Seat Tester
    My Bike(s)
    2008 YZ450
    Location
    NOVA SCOTIA
    Posts
    70
    Nice link to setting floats "the privateer" just seen it.

  12. #11
    Seat Tester
    My Bike(s)
    2008 YZ450
    Location
    NOVA SCOTIA
    Posts
    70
    Here is a 2003 rm250 hopup guide that I got my dealer to get for me. They still call for big jets. I tried it and fouled a couple of plugs. Also the power valve setting is half a turn in either direction. Didn't know that......
    Attached Files


 

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