2007 crf250r won't stop backfiring

5 replies to this topic
  • yamaharider367

Posted July 11, 2009 - 08:40 AM


well to start I haven't been on a 250f since 06 but I missed it so much that i picked up a 2007 for cheap. the previous owner ran race fuel in the bike(not sure what octane i think 110) well i ran that true the bike now im back on 93 pump gas and now it backfires like crazy. every time i ride and let off the gas its just a bunch of backfire. how can i make it stop. bike still runs great just back fires alot.

  • Nick777

Posted July 11, 2009 - 09:09 AM


jetting, mine did the exact same thing, then i changed the jetting and there is hardly any backfiring, if any at all now.

  • yamaharider367

Posted July 11, 2009 - 02:16 PM


i know this will sound stupid but how do i adjust the jetting. I'm good with tools just never messed with a crab before

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • yamaharider367

Posted July 11, 2009 - 06:10 PM


come on guys help a brother out

  • ebeck

Posted July 11, 2009 - 06:37 PM


Under the carb under the bowl. You can get to it from the 17mm drain plig with out removing the bowl as well. Follow the arrow labeled Pilot jet.
Posted Image

You un-screw it, like this.
Posted Image

It looks like this:
Posted Image

If it is popping when you decelerate you need a larger pilot. 07 with a stock cam you probably need a 72. The pilot size is etched on the pilot jet.

  • yamaharider367

Posted July 11, 2009 - 07:45 PM


thanks. also what exhaust do u have on your 07?

Related Content


2004 CRF250R HEADLIGHT by fsmith1221

Dirt Bike   Make / Model Specific   Honda   CRF250R
  • 4 replies

Honda CRF250R 2017 by Chris.GVS

Honda CRF250R 2017
  • - - - - -
  • 0 reviews

Honda CRF250R 2016 by zing

Honda CRF250R 2016
  • * * * * -
  • 5 reviews
  • Last review by Mark Matthews
  • On January 08, 2017

Crf250r starting help by Mghonda

Dirt Bike   Make / Model Specific   Honda   CRF250R
  • Hot  48 replies

230 Fork swap Spring 2016 - options by usedtobefast

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • 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.