1996 RM250 carb fouling plugs

Discussion in '2-Stroke Discussion' started by anthony96rm250, Oct 18, 2008.



  1. anthony96rm250

    anthony96rm250 Rookie DRN Member

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    1999 Rm 250 Plug probs JEtting


    i have a 96 rm 250 runs great and exellent power but there is a bit too much spooge and fouls about 3 plugs on a full day ride and smokes ok but hate having ot change plugs // and i went riding today and fouled about 3 plugs!

    1996 rm250

    Socal High dessert riding elevation about 3000 ft. "summer winter " summer 85 f to 100 degrees F in summer and winter about 80 degrees i ride in the open dessert half the time really pushing the bike most wide open
    and dessert trails kinda fast

    mods are " fmf turbince core 2 silencer " stock everything else " air lid cover on

    carb jets stock
    main jet 172
    slow jet 58
    needle clip position #2 from top
    stock needle
    idle adjustment about 1 turn out
    air fuel screw about 1 or 1 1/2 out

    "just repacked the silencer " Spark plug ive tried "br9eg " does ok too much spooge / and ive tried br8es good but fouled out 2 today in my ride // i want to try br8eg or br9eix iridum. IVE NOTICED THAT THE HOTTER THE PLUG THE LESS SPOOGE AND IVE CHANGED SPARK PLUG GAP A BIT BIGGER GAP IT WAS RECOMMED BY FRIEND IT HELPS! BUT NOT ENOUGH WILL A BR8EIX HELP THE PLUG FOULING ?




    Running cond. needing cured it that i dont want if to foul plugs and less spooge / and im running maxima super m at about 36:1 "previous owner said to run 42:1 on golden spectro " havent tried that yet

    ive noticed that plugs are wet black oily and sinced i changed the gap it looked better


    my reeds PICS
    [​IMG]

    [​IMG]
    Last edited: Oct 19, 2008
  2. bwood

    bwood Rookie DRN Member

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    The lower the number on NGK plugs the hotter. The factory plug for the 96-00 RM250 (according to NGK) is a R6918B-7 and they are expensive $25+. If you have been using BR8ES, the BR8EG will work also. The ES is a standard plug and the EG is a racing plug with a "Fine Wire Nickel Alloy Center Electrode".

    But, it really sounds like a mechanical issue weather it be jetting, a leaking right side crank seal, bad reeds or a worn top end. I checked FMF's jetting center and they show similar jetting. Do you have to top your trans oil off often? THis could be a sign you are burning trans oil due to a leaking crank seal, simulating a lean condition.

    Also remember that your oil mix and your jetting are two different things. Your oil mix refers to the amount of 2stroke oil in you fuel and the lubricating properties of the mix. 32:1 (16oz of oil to 4gal fuel) is 32 parts fuel to 1 part oil and 40:1 (16oz of oil to 5gal of fuel) is 40 parts fuel to 1 part oil. The more oil you run in the fuel, the better the bottom end and rings will love you.

    Your jetting refers to how the carb mixes the fuel/oil mix and air that feed you cylinder. A rich mixture is a fuel to air mix with excess fuel. This will put more fuel/oil mix in the cylinder than it can burn at a certian rpm. Running rich generally will not hurt an engine, nut it can have plug issues and excess exhaust spooge. Running an engine lean means the fuel to air mix has excess air and is using less fuel for combustion, but remember less fuel in the cylinder means less lubrication. Running an engine lean will cause premature failure of the bottom end, piston/rings and possibly powervalve components. Also it can cause overheating and inconsistant performance (mainly due to overheating).

    My 99 CR250 was a little lean on the bottom end to allow low speed woods riding w/o loading up and blubbering when it was time to open it up. Then was more rich on the top. I always used the BR8EG, it was also the stock plug.

    I would start with failed parts first (ie crank seal or reeds), then doulble check the reeds. I believe there are some jetting links somewhere in the "sticky posts". Search them and see what you find. I would also recommend a service manual of some sort if you don't already have one. A Clymer manual will run you $32.95 at Tucker Rocky dealer (most bike dealer a TR reps).
  3. anthony96rm250

    anthony96rm250 Rookie DRN Member

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    no bad crank seal / i dont know about reeds and top seem very good are stock what about the br8eix iridium plugs those are race plugs ,are they really good agianst fouling ?heard they were.
  4. bwood

    bwood Rookie DRN Member

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    Nothings going to hold up to excess fuel or oil fouling. It might last longer than the last one but it will still foul. @ $7.00 ea( http://www.oreillyauto.com/EW3/Disp...archFor=5044&bid=1224392174713&cycleCount=921 ), it could get expensive quick. No disrespect intended, but how are you sure the top end and seal are not to blame? Stock components wearout also. The bike is a 96, so if the piston was changed twice a year (not racing, just recreation riding), you should be on your 24 piston. Racing, well the engine would have been completly rebuit a few times.
  5. dirt bike dave

    dirt bike dave Sponsoring Member

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    FWIW, I've heard some of the RMs had serious carb problems that developed over time. The way I've heard it, the carbs develop microscopic cracks between the float bowl and the venturi. Not visible to the naked eye. Fuel gets sucked through the cracks, causing excess fuel consumption and plug fouling. Regreablly, the solution is a new carb. Not sure if your year is one of he ones affected.
  6. anthony96rm250

    anthony96rm250 Rookie DRN Member

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    yeah i dont know the bike is stock and has been never open i have looked at piston from pipe ehuast outlet and carb cleaned
  7. bwood

    bwood Rookie DRN Member

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    Just looking at it from the exhaust/intake port doesn't mean everythingis ok. I just means nothing is tearing up the piston and cylinder yet. The way to be sure would be to remove the cylinder head an check ring gaps and clearances.

    How long have you owned the bike?
    How often do you ride?
    What have you done to it since you bought it?

    These are some things to think about when guessing/estimating the wear on engine components with out tearing it down for inspection. When I rebuilt my 99CR, I torn the top end down about once every two months just to see how it was all wearing. I rode a couple times a week and raced some cross country about once a month or so, sometimes more. I found that about the 5-6 month mark things were wore enough to replace. I made this the standard for my bike and style of riding. If you are spending time in dusty sandy conditions like desert riding wear my be increased.
  8. anthony96rm250

    anthony96rm250 Rookie DRN Member

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    owned the bike for about a year / i taken to ride the bike about 6 times to the desert and the previous owners took on some slow trail rides and first owner hardly used it the bike has low hours and very taken care of // i have done tranny oil clean my silencer , pipe "very little carbon buildup", cleaned the carb 2-3 times , havent clean air filter yet / still think it is good , new throttle cable ,
  9. bwood

    bwood Rookie DRN Member

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    Ok clean you air filter. Its easy, you should do it every time you ride in any kind of dusty conditions, the oil will begin to breakdown over time which can cause the filter to do the same and it is you first defence in protecting the engine. Has it been fouling plugs since you got it?
  10. anthony96rm250

    anthony96rm250 Rookie DRN Member

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    yes it has when we bought it" the previous owner used to ride at mountian trail rides at high elevations , and they had a br8eg plug in it so when i bought it i ran 927 maxima at 32:1 and fouled out and cracked the br8eg and never tried a br8eg agian but im going to clean the air filter today and buy br8eg and br8eix
    " the previous owner said to always carry a extra spark plug with me" hint hint it was fouling plugs on him too
  11. bwood

    bwood Rookie DRN Member

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    If you are positive its not the crank seal or reeds, definitely look at jetting. I would check the jetting sticky link http://www.dirtrider.net/forums3/showthread.php?t=42618 and go from there. Jetting definitely changes with altitude. An owners manual will usually show necessary changes in a jetting chart.
  12. anthony96rm250

    anthony96rm250 Rookie DRN Member

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    just finished cleaning air filter,
    not sure need to check the reeds later // just rode yesterday will check my tranny oil if it is losing oil.
  13. _JOE_

    _JOE_ Subscriber

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    What fuel are you running?
  14. anthony96rm250

    anthony96rm250 Rookie DRN Member

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    um dont remember it was either 87 octane or it was 91 octane it was problably 91 i dont remember with maxima super 2 at about 36:1
    with br9eg ran ok but too much spooge fouled out after 45 minutes then went riding yesterday and ran two br8es and ran good too but fouled out after about 45 minutes on each im gonna go get the br8eg or br8eix later since i ran out of spark plugs yesterday
  15. anthony96rm250

    anthony96rm250 Rookie DRN Member

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    looked at reeds today took pics what ya think

    [​IMG]
    [​IMG]
  16. bwood

    bwood Rookie DRN Member

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    Take your reeds and look through the carb side, and if you can see light at the lip, they need to be replaced. Those look like Boyseen Super Stock Fiber Reeds. They are very flexible and don't seem to seal very well. I have run into issues using these without rejetting. I would recommend Boyseen Super Stock Carbon Fiber Reeds if the reed block is in good shape. If the reed block looks burned or has inperfections around the sealing area it needs to be replaced. If so I recommend, the V Force 3 reed valve http://www.rockymountainatv.com/pro...el&webTypeId=80&webCatId=16&prodFamilyId=3275 . This was the best upgrade I made to my 99 CR. Between this and the FMF setup I had, it wasn't the same bike.
  17. bwood

    bwood Rookie DRN Member

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    One more thing, I would recommend always using the highest octane gas you can get from the pump (here is Texas is 93). Most MX bikes are designed for 91-92 octane minimum.
  18. anthony96rm250

    anthony96rm250 Rookie DRN Member

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    i think there stock
  19. _JOE_

    _JOE_ Subscriber

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    I think so too. I would replace them just due to the age and price. I would suggest a leak down test and new top end as well.
  20. anthony96rm250

    anthony96rm250 Rookie DRN Member

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    yeah dont have money for it and it runs great anyways maybe later ,,
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