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BrianVivian

2005 WR450 throttle stop

15 posts in this topic

I'm picking up my 2005 450 in about an hour. Anyone know if the throttle stop mod is the same as the 2003-2004 bikes?

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I just left one of our local dealers and the owner said pretty much all the modifications are the same. I'll be checking mine out this Sunday to see what will be required to change on the California models to get rid of the "Smog pump".

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I understand it may weigh a pound, but I'm curious how it would affect performance. Doesn't it just pump air into the exhaust? If there is not a significant impact on performance, then it seems like less pollution is a good thing. Interested to hear from those who know the real effect on performance.

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I just left one of our local dealers and the owner said pretty much all the modifications are the same. I'll be checking mine out this Sunday to see what will be required to change on the California models to get rid of the "Smog pump".

OK, mine's in the garage as we speak and I'm looking at the pictures of the stop mod, but something's amiss (or I'm waaay confused). Anyone else have a 2005 who want to compare notes?

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The additional air introduceed into the exhaust will slightly change the temperature and pulse dynamics (so my engineer friends tell me!) of the exhaust. This may or may not cause issues with aggrevated carb jetting problems once you begin to fidle with aftermarket exhaust systems, cam profiles/timing, ignition timing etc. The stock system is carefully orchestrated to acheive a desired result to satify the eco police. Depending on the level of modification and how much air is introduced into the exhaust and and the operating state of the engine(load)you may have problems ranging from annoying popping on decel to excseccively high exhaust gas temps at WOT.

My advise is this;

If you are going to leave the bike nearly stock and you are concerned about the quality of air you breethe leave it alone.

If you plan on doing major mods or are going to be racing the machine tear it off but I wouldn't chuck the parts just yet. You never know when the laws might change and you are required to have a 'smog inspection' to get your oHV sticker. I wouldn't loose sleep over it, There are plenty corporate and government polluters the feds don't give a turd about.

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If my 05 is a dog compared to my 03, the smog pump goes. Putting a smog pump on a bike is a joke. They will close all local riding areas, force you to burn a tank of gas in your truck getting to a riding area only to burn 3 or 4 gallons while riding. Does anyone know if the non-California bikes or Canadien bikes have the pump?

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To answer my own question...The stop mod is the same (kinda) as on thw 03->04 bikes. You have to take the smog pump thingy out of the way to get to the 2 bolts that hold the cover on. Once that's done, the rest of the faq applies.

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okay, i'm just a "hick" here in the mid-west, but i will never understand why people think an air pump(smog pump?)makes a bike pollute less. a fuel air mix goes in the motor. power is produced. exhaust leaves the motor. air is mixed with exhaust AFTER it leaves the cylinder. isn't the same amount of "stuff" coming out of the motor? it just gets watered down before a meter is stuck in the exhaust pipe.

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okay, i'm just a "hick" here in the mid-west, but i will never understand why people think an air pump(smog pump?)makes a bike pollute less. a fuel air mix goes in the motor. power is produced. exhaust leaves the motor. air is mixed with exhaust AFTER it leaves the cylinder. isn't the same amount of "stuff" coming out of the motor? it just gets watered down before a meter is stuck in the exhaust pipe.

No, by adding air into the exhaust, it assist in burning any unburnt fuel, this unburnt fuel is known as HC's or hydrocarbons. Combustion is not 100% complete, if it was, the only thing we'd get is water and carbon dioxide, then we'd be in trouble for emitting too many greenhouse gases! So as long as combustion isnt 100%, they can reduce unwanted pollutants this way. CO is a result of partially burnt fuel, also known as carbon monoxide. This assit in completing the burn cycle to reduce this also. A 4 cycle engine is much more effeceint as far as combustion goes compared to a 2 cycle, but the greenies arent content with the move to 4 strokes, there end goal is to get you off that bike and on foot or in public transit!

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First and intro, this is my first TT post. My name is Mike and I race District 37 AMA desert. I am just days, if not HOURS away from buying an '05 WR450. The first thing I did when I bought my XR650 was YANK the "smog pump" off....I plan on doing the same with the WR! So when someone figures out the sano removal method...please share. Nice to meet you fine T :thumbsup:humper types!

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thanks for the info. so the idea is to get some more air in there to allow the "fire" to keep burning. kinda like blowing on a camp fire to get it going. a good hot fire doesn't smoke much but one that smolders is a mess. i wonder how long it will be before we have a catalytic type exhaust. we all know a catalytic converter gets very hot, does the smog pump increase exhaust temp very much?

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Some (maybe all) of the BMW bikes have a catalytic converter. I had considered getting the 650, but the thought of dropping the bike with an incredibly hot catalytic converter made me reconsider. And here in CA, a hot catalytic converter is just the wrong thing to have on a bike that goes in dry brush. I doubt any manufacturer would pursue that for a dirt bike.

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I'm with ya........ The throttle stop on my 05 I just got home today, measures 35mm from tip to tip....... all others on this forum have 30 or 33mm...... I aint cuting a thing till someone else measures a 35 allso!

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The 05 sure shook everyone up with this tiny little device. My bike ran no different with it installed as it does now removed. Performance wise, the port at the exhuast valve is different for the 05 and the only real way to tell if it affects performance is to install a 04 head or have it machined. I sometimes wonder if i should have left it alone. It is too late now because I cut the pipe and had it TIG welded shut.

As for the throttle stop. I looked closely at my carb when it was off for re-jet. I had previously removed the screw and cut it the 11MM my local Yama dealer told me to cut. Later I heard TT users say make it 18MM total shank length. When I rotated the carb the original 11MM was not quite enough to fully open the gates. I removed another MM or so until I saw the gates fully open with the screw fully torqued. I did not get a accurate measurement of the screw but I know it is just under the 18MM length others have spoken about. Not worth the $13 savings over a YZ screw!!!

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Measure from the bottom of the head (not the OAL) to the end of the threads and then cut it to match the dimension posted on the thumperfaq.com webpage. I beleive I cut mine down to like 20.00mm or so from a stem length of 28. The whole goal is to get an open throttle, but not to over travel the slide and get it to hang up / open :)

Or buy the YZ part 5NL-14591-00-00

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