06 yz450f backfire


9 replies to this topic
  • Dirtbiker88

Posted June 13, 2013 - 05:17 PM

#1

I have a 2006 yz450f i got about 3 weeks ago it had no spark so i fixed that now it runs its just that on deceleration it backfires quite a bit i know my problem lies in the carb im just wandering what i should change. Needle position, pilot jet, main jet. I don't know any help would be appreciated.


Thanks

  • rangerclass7sx

Posted June 13, 2013 - 07:09 PM

#2

my 04 did the same it was running lean poppin like crazy when decelerating. i just richend the air fuel mixture screw at the bottom of the carb and now shes a little rich . but i think thats better than lean

  • Aro

Posted June 13, 2013 - 07:26 PM

#3

usually main or pilot jet up 1/2 sizes will fix this. if not, then there's air getting into your pipe

  • Slow and Jerky

Posted June 14, 2013 - 05:22 AM

#4

I have a 2006 yz450f i got about 3 weeks ago it had no spark so i fixed that now it runs its just that on deceleration it backfires quite a bit i know my problem lies in the carb im just wandering what i should change. Needle position, pilot jet, main jet. I don't know any help would be appreciated.


Thanks


I would start with exhaust leaks, particularly at the joint where the head pipe meets the tail pipe. Carb might need some work, but if it's running good other than the poping it's most likely exhaust. There is a jetting database in the sticky section that is really helpful to get some idea for jetting at your altitude.

  • grayracer513

Posted June 14, 2013 - 06:29 AM

#5

It's never the main jet.

Look for anything loose or leaking in the exhaust system FIRST, then try trimming the pilot screw. If it doesn't trim out and run right, the pilot jet may be partly clogged.

Read:
http://www.thumperta...599#post3710599

http://www.thumperfa.../jetting.htm#PJ

http://www.thumperta...ad.php?t=327405

http://www.thumperta...726#post8021726

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Dirtbiker88

Posted June 14, 2013 - 07:25 AM

#6

Ok thanks for the help I try doing this tonight

  • Team_Oatmeal_Pie

Posted June 15, 2013 - 10:43 PM

#7

stock come with 42 pilot, which is why it pops on decel (too lean).

I bumped mine to a 45 and its better but still has some pop. I have since bought at 48 and havent put it in yet.

Ton of posts here and magazine articles on what is needed to fix the 2006 jetting.

  • grayracer513

Posted June 16, 2013 - 09:04 AM

#8

Once again, a correctly jetted and tuned YZ450 should pop off some on deceleration. It's just a natural characteristic of certain engines. Most people who have fattened up the idle circuit to completely eliminate all of it discover that their bike runs a bit dirty or stalls more readily on sudden throttle chops from low RPM loads.

Popping a couple of times on most decelerations should be considered fairly normal in most cases.

http://www.thumperta...20#entry2683126

  • Dirtbiker88

Posted June 16, 2013 - 05:41 PM

#9

Well I checked the timing on it and it was way off at tdc so I changed it to what the manual says tool me couple tries but I got it so I fired it up and it ran for about 10 seconds then it died out made a weird noise and it would only run on choke when it did run. Any ideas?

  • Yz400f Jeff

Posted June 17, 2013 - 05:34 AM

#10

Had the same problem on my 400f. I took the 45 pilot out and put in a 48 works a lot better now but still likes the choke a bit till it is HOT. My fuel screw is anywhere from 2.5-3 turns out from lightly seated.





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