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rebelpphead

HELP!!!!!! 06 wr450 loud popping and flames on decel

24 posts in this topic

HELP!!!!!!"06 wr 450 popping very loud and flames out exhaust. Exhaust header also gets red.

Have the following mods

Gytr ais removal

grey wire mod

airbox mod

fmf powercore muffler

throttle screw

gytr fuel screw

175 main 52 pilot. All other jets stock

Location NM elevation 7000 feet.

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Glowing header is normal when the bike just sits there idling.

Check the exhaist for any leaks. Did you recently crash?

Has the bike been sitting unused with fuel in it? If so, replace the pilot jet with a NEW one, reset the fuel screw.

Open muffler contributes to the popping.

Check the ACV

New bike to you or have you had it for a long time?

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Bike new to me had 2 weeks. Bike ran great stock with little quiet popping. Fisrt thing I did was clean bowl and jets. After mods when problems started very loud popping and flames

Read forums and started rejetting went from 158 main to 175 in increments went from 45 pilot to 52

Acv looked ok no tears in diaphragm. Crashed one time in sandy arroyo when stock. Have not ridden bike since mods don't want to screw it up. Bike purchased from friend of family who rarely rode it.

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Thanks for the link. I will start from lower jets and see. All the info I found about popping said it was from lean pilot. That's why I've gone up in the jet sizes

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You may want to use the reference guide as a place to start and be sure and check the needle as well. If it is still popping see if you can tell in which throttle range it seems to be acting up, that should help narrow down which jet needs to be adjusted. There are several guides on the TT site to help you with the jetting experience and I suggest starting here: http://www.thumperfaq.com/jetting.htm

Althoug it is a WR250 site it is directly applicable to 450's as well. Good luck!

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ACV springs weaken over time

Exhaust leaks due to a crash and the fact you have an open pipe make popping worse.

You have a race bike, they are usually never coasted, they arte WOT, then 100% on the brakes. Put the stock exhaust back on. You do not need the loud pipe.

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I am normally able to tune out popping on decel by going up on the pilot, but your jetting already sounds crazy rich for 7000 ft. As a reference my jetting for an '08 is 168 main and 48 pilot and zero popping on decel at sea level. Another thing that will make your bike pop on decel is a dirty filter. If your stock pipe already had the pee shooter taken out of the rear section, swapping to an after market exhaust should not affect the jetting much. I swapped to the same muffler with no change in jetting. As recommended below, definitely look through those links and find what jetting is working for your elevation for a good starting point. Make sure the AIS blockoff is securely capped at the cylinder, if not, air entering there could also cause popping.

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Ordering Jd kit today along with leak and air jets. From all the posts regarding jetting seems that everyone has had good success with the jd kit

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Update : took apart Carb found slide plate upside down, fuel filter plugged, one of the vacuum or vents plugged. All diaphragms good. Cleaned everything. Carb going back on bike tomorrow will update

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Update Carb back on popping is gone have slight bog at 3/4 throttle going down to 165 main. Dam glad popping is gone

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Final update: went 160 main 45 pilot. Bike rips no popping at all. Its like a totally different bike with exhaust and free mods and HD kit. Thank you all for your input all of it helped

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Hi, maybe you guy's can help me as well, i have a 06 450 with a yz pipe, pops when decels and doesn't run smooth when sitting at one speed(about 1'4 throttle) i have never rejetted a bike before and don't really understand the numbering you guy's use for the jets,i ride at sea level,any help would be great,and do jd kits have different jets in them? and can i get them in New Zealand? or will they send to here. cheers

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knotty, The JD jet kits come with custom made needles and a couple of main jets. Most of the popping on decel is the pilot jet, which isn't included in the kit. These you have to order from Yamaha , etc.. As for the "surge" this is completely normal and some find it unbearable, while others like me barely find it noticable. The JD jet kit helps lessen the effect, along with any proper jetting. It's not really all that difficult to re-jet a bike, but will seem complicated the first time you do it. Just read the directions carefully, and ask questions if needed. Were here to help!

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cool, thanks for that,still not sure of the jet size (numbers) you guy's talk about,my throttle seems alittle stiff or it might be it just doesn't respond as quick as i thought it would,could that be a jetting problem as well? eg: wheel standing the power isn't coming on smooth,abit slow coming on can be abit scary when on the back wheel lol. just found out my jet sizes,main-165 pilot-45,so with the yz pipe would i go down or up on these?

Edited by knottyv8

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cool, thanks for that,still not sure of the jet size (numbers) you guy's talk about,my throttle seems alittle stiff or it might be it just doesn't respond as quick as i thought it would,could that be a jetting problem as well? eg: wheel standing the power isn't coming on smooth, like it's not there and then all of a sudden it's there,can be abit scary when on the back wheel lol

Striclty speaking your carb has different circuts that function at different throttle positions, with some degree of overlap. The numbers correspond to the size of the opening in the jets. The Main jet affects wide open throttle, and the pilot jet along with the fuel screw affect the idle circut (pilot circut). The needle affects mid-throttle mixture. When you crank the thottle open rapidly, the accelorator pump is in play. It's been my perception and experience that these different circuts of the carb seem to overlap more when things are way out of wack. In other words if you have a main jet that is 5 sizes too big then you might also get a bike that idles funny and has less power at WOT, so then if you start changing the pilot circut to compensate you can lost in a hurry. My jetting was way off from the PO, and this made it hard to figure out exactly what was going on.

http://www.zrxoa.org...jetting-diagram

The hesitation or bog that you describe sounds like something in the carb, (i.e. either jetting or the accelerator pump). You need to be patient and come up with a systematic way to isolate and evaluate each circut so that you don't make something that is already fine worse, like the original poster had done by going huge on the main jet size.

good luck, j-

Edited by jrutkows
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Striclty speaking your carb has different circuts that function at different throttle positions, with some degree of overlap. The numbers correspond to the size of the opening in the jets. The Main jet affects wide open throttle, and the pilot jet along with the fuel screw affect the idle circut (pilot circut). The needle affects mid-throttle mixture. When you crank the thottle open rapidly, the accelorator pump is in play. It's been my perception and experience that these different circuts of the carb seem to overlap more when things are way out of wack. In other words if you have a main jet that is 5 sizes too big then you might also get a bike that idles funny and has less power at WOT, so then if you start changing the pilot circut to compensate you can lost in a hurry. My jetting was way off from the PO, and this made it hard to figure out exactly what was going on.

http://www.zrxoa.org...jetting-diagram

The hesitation or bog that you describe sounds like something in the carb, (i.e. either jetting or the accelerator pump). You need to be patient and come up with a systematic way to isolate and evaluate each circut so that you don't make something that is already fine worse, like the original poster had done by going huge on the main jet size.

good luck, j-

So if you change the the pipe eg: yz pipe, would you go up in jet size with the main? but just leave the pilot? also i just really noticed(just had a ride) when the engine is hot it doesn't like to keep idling

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