Exhaust popping 08 yz450f

5 replies to this topic
  • Rider1998

Posted February 16, 2016 - 10:44 PM


Bought a 08 yz450f bike is immaculate in every way an older gentleman owned it and everything is all original from factory but suspension upgrades. Only question I have is it pops when reved and on deceleration but starts going away the warmer it gets just wondering if that is ok

  • 15thumper

Posted February 17, 2016 - 04:44 AM


Sounds lean pop on decel is normal if not excessive if power loss also then might be more serious like bent valve I'd check pilot jet maybe bump it up I always ran a jd jet kit in my 08 and it was real snappy

  • stevethe

Posted February 17, 2016 - 06:12 AM


It's okay fine for a 08 YZ450 putting a bigger pilot in it may lesson it a little.

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

Posted February 17, 2016 - 07:33 AM


Before doing anything to the carb, be sure you don't have a leak in the exhaust system causing this.  It would be at either end of the header.


If the pipe's OK, then try setting the pilot screw according to the manual.  If that fails to reduce it to a normal level, then go up a jet size on the pilot, but not until you're sure it needs it.  


It's normal for the bike to pop a little some of the time.  It means it's jetted right.





  • Rider1998

Posted February 17, 2016 - 03:27 PM


This thing pops a lot on decel and if you rev it
Guy said the carb was rebuilt with oem stuff and has only had two rides on it. Air screw was 1 3/4 turns out when I got it I bumped it to 2 1/2 and it still does it

  • Rider1998

Posted February 17, 2016 - 07:58 PM


Carb is dirty and I fell to the devil carb cleaner I couldn't remember what rubber would ruin but the slide seal is gone bike has stock jetting 160 main and a 45 pilot 3rd clip position. Question would I have to do any jetting difference with a factory 4.1 slip on no header just the muffler thank you for your help

Related Content


Michigan Motocross Tires by 288yz450

Dirt Bike   Dirt Bike Regional Discussion   North
  • 1 reply
WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info

  • 0 replies

Thinking about Yamaha 250... by Arctic Pride

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  491 replies

First Hare scramble tips by dhend8

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

2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 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.