08 YZ450f. WB PIPE BAckfires


13 replies to this topic
  • yz250o2

Posted October 25, 2007 - 05:01 PM

#1

White Brothers Aluminum Pro Full System
Stock jetting is a 160 and I put a 162 in.

For the pilot stock is 45 I put a 48 in.

Still backfires......even when I twist the throttle.

Also Deacceleration backfiring. When it's doing this I would believe it's lean....but correct me if im wrong. What jetting would you guys use? Please and thank you I want to tear it up!

  • gbalias

Posted October 25, 2007 - 05:13 PM

#2

WB didnt have jetting specs packaged with the pipe?


sounds lean to me.

  • matts06yzf

Posted October 25, 2007 - 05:19 PM

#3

Are you playing with the fuel screw? If you dont have a aftermarket yet get one asap. My 08 is worse than my 06 with adjustment to fuel screw. Temp drops she starts popping alot half a screw out all gone Sweet bike tho huh?

  • yz250o2

Posted October 25, 2007 - 08:54 PM

#4

Yea I bought the fuel screw today. WB jetting specs...MAIN 162 and Pilot 45 stock. Did that and Im lean. Then I did the change today from a 45 to a 48. I might go to the 50 now.

  • swatdoc

Posted October 25, 2007 - 09:04 PM

#5

you might have a mild exhaust leak also. try a little hi temp silicone sealant at the points where the pipe joins

  • yz250o2

Posted October 25, 2007 - 09:15 PM

#6

Thats what I was thinking. But why won't they use clamps? I was kind of surprised. I might go ahead and try and add some sil. Wonder if I should have to touch the needle.

  • wes782

Posted October 25, 2007 - 09:32 PM

#7

try a 168 main and keep the pilot 48, and the way the pipe seals it shouldnt need a clamp... ive been running white bros pipes the last 2 years and never had an exhaust leak.

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  • Racer808

Posted October 26, 2007 - 03:50 AM

#8

you sure the pipe isnt just burning in? New pipes pop alot then it goes away. Here in colorado I went to a 155 main and 48 pilot and its perfect, however my Yosh popped a lot the first two rides. I called they said new pipes have to burn in. But you could also have a leak. however, i dont have a clamp and it doesnt leak

  • Ga450owner

Posted October 26, 2007 - 07:43 AM

#9

What is your altitude? If it is close to sealevel you are rich and need to go down on pj to a 42 -

Look at Jetting guide top of thread

WB pipes need no stinkin ugly clamps....just get some high temp gasket sealer on the header when installing the rear cannister. It must dry 24hrs.

fuel screw and setting is key as is jetting to get this right.....

  • AnotherRedHead

Posted October 26, 2007 - 08:22 AM

#10

Just go up on the main some. 48 pilot should be perfect. Im at sea level, less than 600 ft got 165 main and 48 pilot with stock exhaust. When I had the 160 main and 45 pilot in, ran great in 85 degree temps, but when it was 60 at the night track, it was popping and bangin. Ran great after upping the jetting however.

Nick

  • freerideyz250

Posted October 26, 2007 - 08:45 AM

#11

I'm at 1475 feet. Mine ran perfect box stock, however as soon as I put the new muffler on it, it wouldn't even run. It would bog heavily and die, when trying to give it any amount of throttle. I changed the pilot to 50 and 165 main, and about 2 turns out on the fuel screw. Runs good now, no decel pop, starts okay, no hesitation.

  • todds924

Posted October 26, 2007 - 03:52 PM

#12

White Brothers Aluminum Pro Full System
Stock jetting is a 160 and I put a 162 in.

For the pilot stock is 45 I put a 48 in.

Still backfires......even when I twist the throttle.

Also Deacceleration backfiring. When it's doing this I would believe it's lean....but correct me if im wrong. What jetting would you guys use? Please and thank you I want to tear it up!


The changes you've made sound good to me. I believe all you need to worry about is your fuel screw setting. Try it at 2 turns and work from there.

  • CROGGR

Posted October 26, 2007 - 09:30 PM

#13

You need to richen the needle one position. Stock it is the third position from the top do to the stock restricted exhaust! Put it in the fourth position (07 specs)or middle and you will find the bike will have much better response and the lean symptoms will go away!

  • yz250o2

Posted October 26, 2007 - 09:54 PM

#14

Ya needle sounds like it would help alot. Ill let you guys know how it helps. Thanks all of you guys for working with me a little.





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