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Dart 400F

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About Dart 400F

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  1. Dart 400F

    Stumped, PLEASE HELP.....

    Finally got to tearing into my bike tonight and what did I find........ My plug wire somehow became dislodged from it's intended position. I guess I was freaking over nothing. Thank you for all the great ideas.
  2. Dart 400F

    Stumped, PLEASE HELP.....

    All great suggestions. Thank you all.
  3. Dart 400F

    Stumped, PLEASE HELP.....

    I never thought of that. I'll be doin that this weekend. Thanks for the tip!
  4. Background: 1999 YZ 400F Ran bike last Sat. (ran great) for 3hrs. Started raining, bike sat until it stopped. When it stopped raining I got the bright Idea to go play in the mud. 5 mins into the ride, the bike starts studdering and lerching and having some serious bogging issues. Got so bad that the bike wouldn't even take off from a stand still (would start though very easily). Got it back to camp and It sat for the remainder of the weekend. What I have eliminated I think: Drained about half a gallon of fuel out of the tank thinking water somehow got into the tank. ran it up and down my road for a couple laps and a serious bog issue is still very apparent. I'm thinking water in fuel not the issue? Problems I am considering: Clogged jet/ needle? Bad throttle pos. sensor (if it has one, no Idea)? CDI unit? Please help with any other problems you all might think may help me solve this grand mystery. I feel the bike had plenty of time to dry out before the run through my neighborhood 2 days ago. Could it be just an electrical connection some where? Help Please!!!!
  5. Dart 400F

    accelerator pump timing screw

    I have a 99' YZ400. I installed the Boyseen Quickshot and the directions called for turning the timing screw out (counter) but I could not find the timing screw? Any ideas? Is there even one on the 99' 400?
  6. Dart 400F

    Help Please!

    Thanks for the info, I have no time so I guess I will be paying someones car payment on this one. One other thing guys, Are there any tell tale signs that your valves need Adjustment (shims)? I would really hate to have one come through the top end.
  7. Dart 400F

    Help Please!

    Hello all. I have a 99' 400F and I am very new to the 4 stroke scene. My problem is this. Last year when I would ride, it would cough and choke through the really heavy ridding but while cruising it seemed to run fine. Not sure if this is a jetting problem or a valve problem. When exiting a turn it doesn't want to run unless I keep the throttle up in the midrange (bogs at low RPM). The spitting and rough running previously mentioned would mainly happen while running through a long section of whoops or over rough terrain. Since purchasing I have installed a Boyseen Quickshot accl. pump cover, and I have put on an FMF titanium High Flo header paired with a Powercore IV exhaust. Could the problem be as simple as too much fuel caused by a sticky float in the carb? Any help would be greatly appreciated. Thank-you Lonny
  8. Dart 400F

    first oil change/ filter ?

    If it's colder where you live you would want to use a broader range of viscocity like a 5-10w-40/50. The lower number is the viscocity of the oil 0 degrees F', and the second number is the weight of the oil at operating temp (212 deg. F'! If he used a 20w-50 in cold temp, the oil may not circulate as well at the colder temp! Being in Cali, you could get away with a 20w-50. To get back to the orig question though, you can use whatever oil you prefer. As long as it has an S rating (S for Gasoline engines) and does not contain friction inhibitors, such as Yamalube which is has an SJ rating and no friction inhibitors. Vavoline performance oils have an SG and mobil 1 synthetic is an SH. The ones that have the "Energy Conserving" I or II stamp have friction modifiers. You can tell by looking at the back of the bottle, what type of rating it has. Why pay outrageous prices for these so called "special oils" when the same stuff is sold at auto zone for $1.99 a qt?
  9. A zip tie would accomplish what your saying, correct? Or do I need a clamp (hose clamp style) to secure it somewhere in your opinion?
  10. Hey everyone, I am getting my "thumpertalk" cherry popped with this post. Just bought a used Magura hydro Clutch for my 99 YZ 400F and am wondering, is installation pretty cut and dry or is there modifications that need to be made? I ask this because I do not have a owners manual for the clutch nor do I know the installation procedure, and I have read many horror stories on this product. I have not received the clutch yet (in the mail) but just wanted to try and get some feedback before I attempt to tackle it myself. Thanks all!