New (to me) WR400 won't idle

4 replies to this topic
  • youthenrage

Posted December 03, 2008 - 12:03 PM


I picked up a 98 WR400 cheap on craigslist the other day, I've been riding motorcycles for years (mostly 70's yamahas, lately a KLR650) but this is my first true dirt bike, and my first "modern" bike.

Anyway - the WR400 starts right up once you have the start sequence down, and will run with the choke on, but if you turn the choke off without staying really heavy on the gas, the bike stalls. I've let it run choked for 2-3 minutes, just to make sure it's warm enough and it still stalls. If you stay heavy on the gas and just work the clutch, it runs fine, but as soon as you roll of the throttle, it stalls whether you clutch it or not. The guy I bought it from said he only rides it a couple times a year and it's bone stock, so I'm thinking the carb is all gummed up. Should I just dump some sea foam in the tank and run it through? Or am I better off just pulling the carb and giving a legit cleaning? Should I be looking at anywhere else for the culprit?

  • markseaba

Posted December 03, 2008 - 12:06 PM


pull carb off and clean it. make sure you have fresh gas.
BTW, 2-3 minutes may not be long enough to really warm the bike up.
my WR warms up after I am riding for about 5 minute or more.

good luck..............

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  • glentron

Posted December 03, 2008 - 10:46 PM


I would adjust your idle screw on the left side of your carb. it's a black know that you can turn by hand. You need to turn it to adjust the idle setting. I would turn it all the way to the right and then open it about 2 full turns as a starting point. You can dial the bike in when you can get it continue running with the choke off. I also have a couple of suggestion to make it run good and strong, if you've already done this forgive me. I would replace the spark plug first and gap it properly. this info is in your manual, but I think it's between .26~.31 max gap. Use the NGK plug that the bike came with. I would also clean your air filter and replace the engine oil. I just ran some carb cleaner through my gas to clean it, taking the carb off is just asking for more trouble if you haven't done this before. I have a 99 and it still runs very strong and I love this bike. :usa: You should remove the throttle stop as a nice mod as well. this is on the right side of the carb behind the black cover. There are two bolts that hold this cover on, don't remove until you find the second hidden bolt. The throttle stop is a pin that stops the throttle from opening all the way. when you turn the throttle, you will see a pin that stop the cable linkage/holder from turning. it's at the 5 o clock position of the cable holder and behind the small linkage. It's a 7mm wrench size and about 1 inch long. get an open ended tool that is made very small in size. If you turn the throttle open and bind it with something, you can get to this little guy easier, but it will be a little challenging. Just take your time and turn your wrench over and over and over again to get the pin to turn little by little. I took mine completely out long ago and it runs very strong and your bike will come alive. This is really a mod and it's not neccessary to make your bike idle properly, but you should do this in my opinion. :smirk: I hope this help you get that sweet machining running soon. :thumbsup:

  • youthenrage

Posted December 04, 2008 - 09:49 PM


Thanks guys! I had tried turning the idle screw, turns out it wasn't actually doing anything, I popped off the plastic sheath that covers the right hand side of the carb and started twisting the idle screw, it wasn't moving the throttle stop screw at all. I busted out the needle nose pliers and rotated the throttle stop screw by hand, she idles like a dream now once she's warmed up!

  • oldnyzr

Posted January 01, 2009 - 11:55 AM


So- how much was "Cheap"? Less than $1000?


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