backfire


5 replies to this topic
  • pymn2001

Posted December 17, 2005 - 12:36 PM

#1

Hello folks
my 03 450 keeps b/firing everytime i back off. my old 400 did the same but not every time any ideas , i will be looking at the valve clearances and fueling , :applause: need some ideas where to start first the bike is bog standard and is uk model

  • byggd

Posted December 17, 2005 - 02:04 PM

#2

It it just small backfires or more like a 38 being fired? Small pops are normal on declaration. A backfire is either usually caused by an exhaust leak (cold pocket of air in the exhaust) or lean jetting. What jets are you running??

  • 642MX

Posted December 17, 2005 - 02:49 PM

#3

Try a half turn out on the fuel screw. If its popping and bogging its lean.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • pymn2001

Posted December 21, 2005 - 10:34 AM

#4

thanks for post >> big flame from rear some times im told and dont know about jets will look at plug etc ref mixture yet

  • creeky

Posted December 21, 2005 - 01:03 PM

#5

Usually, backfiring or popping on deceleration is caused by lean jetting or an intake manifold leak.

  • Matty05

Posted December 21, 2005 - 05:46 PM

#6

thanks for post >> big flame from rear some times im told and dont know about jets will look at plug etc ref mixture yet

Byggd right!

Big flame backfire (blue) would be from header or exhaust. Maybe leaky carb boot, but flames I would say exhaust.

I would check everything, but your exhaust first. Just your header out of allignment can make your bike spit foot long blue flames (trust me, been there....) If you have an air leak, jetting changes won't do much all.

You might want to change your exhaust gaskets, when is the last time you changed them?




 
x

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.