01' 426 backfire issue

3 replies to this topic
  • River4Life

Posted February 05, 2006 - 02:00 PM


my neighbors 426 has been sitting for about a year and i decided to take it off his hands. when i run the bike it backfires excessively and runs extremely hot. ive checked the valves, they are ok, changed the oil, cleaned the carburetor and jets, adjusted the idle screw, put new fuel in, checked the coolant and air filter. the one thing i havnt done is adjusted the pilot screw. i dont know the factory number of turns so i havnt touched it. could that resolve my problem and is there anything else i should look for?

  • 642MX

Posted February 05, 2006 - 03:21 PM


I think my pilot screw was turned 1 3/8 out from the factory. But the weather changes daily and so does my fuel screw setting. Turn the fuel screw until the response feels crisp and make sure you don't have any exhaust leaks. A properly tuned YZF will still have a minimal amount of popping and backfiring, so don't go crazy trying to fix all the popping.

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

Posted February 05, 2006 - 06:23 PM


I had a 2000 426-raise the needle one clip- I will still backfire but not as much. Usually on heavy deceleration,plus it scares the crap out of some people in a race and they even move over.

  • crashyz426

Posted February 08, 2006 - 07:27 PM


have you checked the hot start? When I crank the bike using the hot start button it will backfire excessively until I push it back in. It might need adjusting or be stuck or something....just a thought maybe it will help

Related Content


Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies

Thinking about Yamaha 250... by Arctic Pride

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  491 replies
WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info

  • 0 replies

Yamaha YZ450F 2017 by Chris.GVS

Yamaha YZ450F 2017
  • * * * * *
  • 1 review
  • Last review by Tommyk_55
  • On January 15, 2017

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

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.