2009 yz450f

14 replies to this topic
  • TheUSMC1775

Posted April 13, 2014 - 06:23 PM


Hey everybody so I own a 09 yz450f and valves just bin done cam chain just replace, now I'm lost for words on tuning I noticed when in first gear cruising down the street and slowly accelerating it's a mixture of hesitating and chocking but when I shift to second and crack the throttle it's fine not perfect but rideable and are these bikes soppose to get like hot where you can feel it when just riding around ? Not agressive just up and down the street? Thanks

  • YZbumblebee

Posted April 13, 2014 - 08:04 PM


Not to get off subject but where are you located devil? I'm in Camp Pen I'd be willing to help.

  • TheUSMC1775

Posted April 14, 2014 - 01:42 AM


Rah! I'm in north jersey.

  • YZbumblebee

Posted April 14, 2014 - 07:38 AM


They don't have any dirt bikes in Jersey lol.

  • TheUSMC1775

Posted April 14, 2014 - 08:07 AM


I'm one of the few lol

  • TheUSMC1775

Posted April 14, 2014 - 11:41 AM


So how can I resolve this problem?

  • YZbumblebee

Posted April 14, 2014 - 12:02 PM


Sounds like it's not getting enough gas is it upgraded in any way? You may need bigger/smaller jets.

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  • yz133rider

Posted April 14, 2014 - 12:10 PM


Sounds like a clogged pilot jet.  Get a new stock sized pilot jet or one step bigger.  Start there and report back.  Make sure no air leaks on the boots. 

  • grayracer513

Posted April 14, 2014 - 12:18 PM


Start by trimming out the idle mixture first.  You may find that the adjustment process points you toward a clogged pilot jet, or one that's too small.  If the idle mix adjusts out OK, try unplugging the TPS and run it. 

  • etuke

Posted April 14, 2014 - 01:12 PM


unplugging the tps fixed my 07 from stumbling at slow constant throttle

  • TheUSMC1775

Posted April 14, 2014 - 02:41 PM


I will try that and get back to you guys thanks alot!

  • SmokinEvan

Posted April 14, 2014 - 05:05 PM


I vote for TPS Sensor unplug. Worked on mine. Much smoother

  • Bturner

Posted April 14, 2014 - 06:45 PM


I vote for TPS Sensor unplug. Worked on mine. Much smoother

What is this TPS sensor you speak of?  I haven't heard of this one :smashpc:

  • SmokinEvan

Posted April 15, 2014 - 03:52 PM


Throttle Positioning Sensor - there are a couple of threads about it. Disconnecting basically makes the Cdi box think the throttle is wide open. Does not affect anything, gets rid of the choppy throttle. I disconnected mine. It removed the chop and no issue with power/idle/etc..

  • souliog

Posted April 16, 2014 - 11:37 AM


I had to go up 3 or 4 pilot jet sizes with my 2006 yz450. Ran perfectly afterwards. I would need to play with the air/fuel mixture screw to compensate for air temp. Cools down the operating temps considerablly.

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