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03dirtymax

throttle stop????

31 posts in this topic

i just purchased a wr450 and the throttle stroke feels really short. I was told there is a throtle stop and if I remove the carb there is someting inside to grind down which will give full throtle. If any one knows of this or can help that would be great thanks.

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just dont do the throttle stop. Buy the entire GYTR AIS removal kit from yamaha. Its well worth the 45 bucks and an hour of labor.

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Just got that today, actually. It also comes with a #45 leak jet - which is such a :banghead: to find anywhere...

Do the ACV mod while you're in there. Helps with being able to tune the bike at idle without the RPMs floating all over the place. Also helps you set your mixture because you'll know if you're lean (can pop like a YZ).

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30 min come on guys.

2 extentions a swivel and an allen wrench. takes more time to cut it down

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30 min come on guys.

2 extentions a swivel and an allen wrench. takes more time to cut it down

For the throttle stop no problem... even quicker... but for the entire AIS removal kit (i.e., carb removal), an hour from start to finish would be astonishing

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That's a 2-hour job for the average person. You need to change the (included) air jet in the carb bell to a #110 if you use the GYTR kit. That's a freakin' PITA on the aluminum bikes...

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Just got that today, actually. It also comes with a #45 leak jet - which is such a :banghead: to find anywhere...

Do the ACV mod while you're in there. Helps with being able to tune the bike at idle without the RPMs floating all over the place. Also helps you set your mixture because you'll know if you're lean (can pop like a YZ).

what does ACV mean?

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I am from canada and got a 08 wr450 whats is the grey wire do thats so important that every one cuts? ive read all about it on here but what does it control? and does the canadian 08 model have it?

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what does ACV mean?

Auto Coast Valve. It slightly richens the air/fuel mix on decel to minimize popping/backfires. Problem is, sometimes the long pulses of vacuum inherent in a thumper make it act funny thereby making setting the fuel screw a pain. Also, over time it it can go bad, leading to a overly rich mxture all the time. I have not ever (yet) had these problems and therefore tend to leave it operational.

I am from canada and got a 08 wr450 whats is the grey wire do thats so important that every one cuts? ive read all about it on here but what does it control? and does the canadian 08 model have it?

Does your bike have it? Maybe, maybe not, some CDN bikes do, some do not. If you have one, it will be at the CDI. It controls which of two ignition maps your bike uses. The WR one is mild, causeing the engine response to be 'softer' and allow less than optimum grades of fuel to be used. The other map is more YZ like, has crisper throttle response and you must use good quality premium fuel.

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Air cut valve.

It's under the little cap on the left side of the FRC carb on WRs. YZs have the casting for it, but it's not drilled.

This device richens the mixture on decel to prevent exhaust popping. It's nice to have in the woods if you want a quiet bike, but it makes it hard to tune the bike properly. A properly tuned YZ will pop "a little" on decel, the WR should behave the same. That said, if you don't like any popping, you can always disable the ACV, tune the bike, then put the ACV back to stock, but why bother? :banghead:

Check out the FAQ here:

http://www.thumperfaq.com/acv.htm

I use this method since I'm never going to put it back to "stock" and don't want to worry about the rubber plug failing:

1.Remove the ACV cover and carefully remove the spring and the diaphragm.

2. Put some JBweld or Red RTV in the hole in the small O-ring.

3. Replace the diaphragm in the ACV cavity backwards with the pin pointing out.

4. Replace the spring and the cover.

Here's a link to how carbs work, including ACVs:

http://www.4strokes.com/tech/carbover.asp

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That's a 2-hour job for the average person. You need to change the (included) air jet in the carb bell to a #110 if you use the GYTR kit. That's a freakin' PITA on the aluminum bikes...

Yup, pulling the carb or even getting to the slow air jets is a royal PITA. You want to think about and plan carb work according to the level of effort! A good wrench can do it all in under 45 minutes. But if you have limited mechanical experience, give yourself a whole day. Take your time, think, do not force. If you feel frustrated, take a brak before you break something.

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I am from canada and got a 08 wr450 whats is the grey wire do thats so important that every one cuts? ive read all about it on here but what does it control? and does the canadian 08 model have it?

The grey wire (when connected) changes the ignition curve from a YZ curve to a WR curve (different advance mapping). You gain a fairly large performance improvement by cutting or removing and taping the grey wire. The ECU is located on the left side of the bike under the plastic behind the airbox. The connector is right there.

I don't know about the feature on the Canadian-market bikes. It only takes a few minutes to check it out.

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awesome thanks to every one for their replys. im just getting used to htis web site so thanks again to every one. one more quick Q...what does AIS stand for? air intake system?

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ive been reading that the stock mufflers suck.. im guessin its pretty well personal choice but what are some types / brands of mufflers ppl like to put on these bikes.

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AIS=Air Injection system

Before you pull the muffler and get all loud, get a James Dean jet kit, remove the snorkle, do the throttle stop, grey wire (if it exists) first, then decide, "is the bike too slow for you?"

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AIS=Air Injection system

Before you pull the muffler and get all loud, get a James Dean jet kit, remove the snorkle, do the throttle stop, grey wire (if it exists) first, then decide, "is the bike too slow for you?"

okie.. should i hold off on the AIS and acv mod then too?

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