YZ400F Won't Start


3 replies to this topic
  • Peter S.

Posted April 03, 2015 - 11:29 PM

#1

Hey all,

 

I have a 1999 yz400f that I took on a series of desert rides over the last week. All week the bike ran perfect, started in 1-3 kicks, and was a genuinely joyous bike to ride. Coolant always topped off, ran on non-ethanol 92 gasoline. Oil changed every 12 hrs. On the  last day of riding, I started the bike first kick when I unloaded it. It ran for around 10-20 seconds before I hit the kill switch. around 5 minutes later, I started it first kick again to warm it up. It ran for 5 seconds then died. It has not started since. Fuel was on, air filter clean, and I have tried kicking and bump-starting repeatedly. I have tried choke and hot start on, off and every combination of the two. Nothing. It will not start. Why is this? I suspect a fowled plug, although I have never had a 4-stroke do this before.  Bike makes good compression. Any thoughts? Thanks in advance. 



  • springer8828

Posted April 04, 2015 - 05:57 AM

#2

As funny as this may sound check your spark plug

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • grayracer513

Posted April 04, 2015 - 06:10 PM

#3

With the older YZF models, the 400's and 426's that have a frame mounted coil and a plug wire, always start with a fresh plug.  The ignition isn't very strong at cranking RPM, so it doesn't take much to foul them.  It's wise to check to see if you have spark, of course.



  • Peter S.

Posted April 07, 2015 - 10:25 AM

#4

Replaced the spark plug, Bike started second kick, smoked like crazy for 3 minutes, then ran exactly normal. Carb also overflowed gas for a few minutes, then functioned normally. Old plug was black and the gap was smaller due to the end being bent in.





Related Content

Reviews

Yamaha YZ450F 2017 by Chris.GVS


Yamaha YZ450F 2017
  • * * * * *
  • 1 review
  • Last review by Tommyk_55
  • On January 15, 2017
Forums
Photo

Is it worth it? (Cam and High compression piston) by macgi77


Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies
Forums
Photo
Supercross

Wilson the Blue Privateer by jetfuel


Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  50 replies
Forums
Photo

Chubby dad, looking at bikes , First trip to the orange/black forum ! by Slow_ride


Dirt Bike   Make / Model Specific   KTM   250-530 EXC/MXC/SXC/XC-W/XCR-W (4-Strokes)
  • Hot  28 replies
Forums
Photo

YZ450FX OR YZ450F by MESSMAKER


Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  30 replies
 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.