yz400f ?

5 replies to this topic
  • Lawrence Olson

Posted May 11, 2016 - 05:45 PM


I have a 99yz400f. Bike has been giving me a problem :banghead: \. During the last ride towards the end of the ride i notice a loss in power and it was popping :facepalm: . Since then i have cleaned the carb and got it running nice no popping. takes a few kicks to start. but still have a no power problem. i know its a four stroke but think of it ths way i have no powerband. Almost like its in limp mode only applys so much power. could this be a cdi issue?

  • downonmonday

Posted May 11, 2016 - 10:02 PM


When was the last rebuild?

  • grayracer513

Posted May 12, 2016 - 06:21 AM


Check your cam timing. 

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

Posted May 12, 2016 - 07:19 AM


+1 on cam timing. Also check valve clearances, they can lead to problems with hot starting.

  • Lawrence Olson

Posted May 12, 2016 - 03:56 PM


:thumbsup: thanks guys for the replies. it starts just fine when hot. runs and idles great. if your a mechanic think of it as its in limp mode :lame: 


  • Lawrence Olson

Posted May 14, 2016 - 12:49 PM


forgot to add one thing a few times i would go to kick it over and it would act as if i had the decomp lever pulled. when i didn't. so i think yo may have something there with a valve problem :rolleyes:

Related Content


The "going back to the other darkside" adventure... by Monk

Dirt Bike   Make / Model Specific   KTM   250/350/450/505 SX-F & XC-F (4-Strokes)
  • Hot  113 replies

James Stewart back on a YZ450F by YamaLink

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  47 replies

yz250x vs 450 4t comparisons (preferably desert riding) needed by JakeNorthrupYZ450F

Dirt Bike   Make / Model Specific   Yamaha   Yamaha 2-Stroke
  • 9 replies

Should I buy this bike? help....... by Numsa Hul

Dirt Bike   General Dirt Bike Forums   What bike should I buy?
  • * * * * *
  • 10 replies

Megabomb Fitment by 288yz450

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply

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.