i think this is a dumm q...

3 replies to this topic
  • yz450fensenada

Posted January 23, 2005 - 10:13 PM


i think tis is a dum question but im gonna ask you guys anyways...
i just noticed that my yz 450f when pinned on the rev limiter it will shoot some fire and sparks out the exhaust thats normal right??


  • grayracer513

Posted January 23, 2005 - 11:49 PM


I hope you noticed this while someone else was on the bike, and not ...nevermind. :cry:

Yes, it's normal. Think about what's happening. A rev limiter works by turning off the ignition above a preset speed. As soon as this happens, the bike slows down, whereupon it falls below the rev limit, and the ignition comes back on. The fuel system was working just fine during this little intermission, however, but since there was no spark, the fuel that was delivered to the cylinder didn't burn and ended up in the exhaust. When the lights came back on, the flame from the once again running engine ignited the fuel in the exhaust pipe, creating your fireworks display. This is why, BTW, rev limiters on electronically fuel injected engines always cut the fuel off, rather than the spark. Taking this approach prevents the flames and popping, but it can't be done with a carb.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • yz450fensenada

Posted January 24, 2005 - 12:34 PM


hahahah thanks!!

  • yz426onNOS

Posted January 24, 2005 - 05:11 PM


Also if you run them rich a nice flame will shoot out as well.

Related Content


Megabomb Fitment by 288yz450

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply

Thinking about Yamaha 250... by Arctic Pride

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  491 replies

Michigan Motocross Tires by 288yz450

Dirt Bike   Dirt Bike Regional Discussion   North
  • 1 reply

YZ450F 03 Sparks driving me crazy by SirAttard

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 5 replies

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

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