Installed 08 450F Carb on '99 400F...

4 replies to this topic
  • Coonass400

Posted March 30, 2010 - 07:06 PM


Thanks SXP and Grayracer for the help. I installed the 08 carb on my 99 400 and she hasn't run this good since I owned her. No more hanging idle and no more popping after countless attempts at cleaning/setting/jetting, etc. to the old carb. That said, the bike still has a bog when wacking the throttle open quickly but that seems like a common problem still to alot of bikes. Any ideas to better this situation. I've searched a little on the subject but haven't really dug into it yet. Thanks again everybody:thumbsup:

  • JandJ07

Posted March 30, 2010 - 07:11 PM


Its normal. You will never notice it during normal riding conditions. :thumbsup:

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • tek_01

Posted March 31, 2010 - 02:39 PM


Stiffer accelerator pump spring like the on from merge racing? although i think the 08s have a fairly stiff spring already.
Also if you do get the spring there is also a procedure on how to set the AP squirt timing.
I done this on mine (05) and it helped a lot to the point i cant notice it.

  • Family Man

Posted March 31, 2010 - 09:07 PM


Do a search for the oring mod.

  • grayracer513

Posted March 31, 2010 - 10:53 PM


Stiffer accelerator pump spring like the on from merge racing?

Do a search for the oring mod.

Neither of these, IMO, is necessary. They are, of course both the same thing, except that one uses a real carb part, and the other is a rubber band job.

If the carb is tuned and jetted right, including the previously mentioned pump timing, and you teach yourself the simple reflex of rolling the throttle open instead of snapping it, the engine will never actually bog while you ride it.

Related Content


2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies

James Stewart back on a YZ450F by YamaLink

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  47 replies

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

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

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