13 yz450f running poorly

3 replies to this topic
  • Dangerranger1973

Posted December 14, 2015 - 08:09 PM


So I went riding about a month ago and while warming the bike up it was idling for about 2 min and then hit the kill switch and made a weird noise then I went to start it and was rolling the engine over to get to tdc and it stopped. So I pulled the valve cover and found that the intake valve closes to the timing chain was stuck down and intake cam had jumped time.

Got the bike home and pulled head off. No piston/valve contact. when I pulled the cams I found the bucket is broke. Got he bucket out of the head and removed the valve from head. Used a dry erase marker and marked the seat put light pressure on valve and just enough to disturbe the marker and it is sealing good. I was able to repair the head and install a new bucket.

Installed head and put bike back together. Slowly kicked it about 20 times to get oil back up to the head. Fired bike up and it was idling really rough and rich. Let it run for about a min and then shut it off. Went out the next day to work on it and same thing. But after about 10-15 seconds of running it died and would not restart. Started looking around and found the intake temp sensor right above the throttle body in the air filter housing was not plugged in. Plugged it in and put a new plug in cause the old plug was so fuel fouled it had no spark.

Bike starts and running super rich I get a small cloud of black smoke out the pipe. Similar to a 2 stroke smoke cloud when hitting the throttle.

Will the intake temp sensor not being plugged in cause it to run like this? I know I have ran it long enough to set a code for the temp sensor. Now that it is plugged in will it clear itself after a ? Times starting and running or is this something that will need to be cleared with a computer?

  • Ctown208

Posted December 14, 2015 - 09:28 PM


Just wondering if you replaced the cam chain tensioner when you redid it. Probably not a bad idea.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Dangerranger1973

Posted December 15, 2015 - 06:49 AM


Yes new bucket, head gasket and tensioner,

  • grayracer513

Posted December 15, 2015 - 07:34 AM


In the OBDII world, an open IAT sensor circuit code will not clear itself automatically once corrected.  I don't know about on the YZ, but I'm pretty sure you'd have to clear it manually.  


On the other hand, stored history codes generally have no effect on unit operation if the condition that set the code is fixed. 

Related Content


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

yz400f throttle bog by yz400fmaniac

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • * * * * *
  • Hot  28 replies

Thinking about Yamaha 250... by Arctic Pride

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  491 replies

Michigan Motocross Tires by 288yz450

Dirt Bike   Dirt Bike Regional Discussion   North
  • 1 reply

First Hare scramble tips by dhend8

Dirt Bike   General Dirt Bike Forums   General Dirt Bike Discussion
  • Hot  33 replies

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.