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'05 WR off idle stumble/rough acceleration

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I've been searching & searching and believe my problem lies with a slightly rich needle condition in the transition from idle to mid-range, but wanted to ask you guys first.

Here's my symptom: Bike idles nicely, but stumbles/accelerates roughly thru the mid-range. On the first day of riding with the JD blue needle, it was incredibly hot & humid, and I thought for sure a switch to the JD red would cure the stumble, as per the charts recommendation. So a week later after switching to the red, I test drove it, and while it was nowhere near as hot & humid, the stumble was very much still there.

I have not done the Grey wire mod yet, so was wondering if this could be part of the problem?

ACV?

My bikes airbox is opened up and has an FMF factory 4 exhaust pipe, so it's definately breathing better than stock.

My jetting is as follows:

-Red JD needle 5th from top

-185 main

-72 starter

-40 pilot

-50 leak

-Fat O-ring on accelerator linkage

-2 out on adjustable air/fuel screw

Riding conditions in NY are:

1400' elevation

fairly humid lately 50% to 70%

temps in the high 80's

Please don't automatically move this over to the jetting forum, as I would like some input from fellow WR riders first. Thanks!!!

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I have practically the same problem as you ATM

Whilst riding from 1/4 to 1/2 throttle there's like a flat spot and it' sputters... I ignore it and keep riding... If I find a solution ill tell ya

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I have practically the same problem as you ATM

Whilst riding from 1/4 to 1/2 throttle there's like a flat spot and it' sputters... I ignore it and keep riding... If I find a solution ill tell ya

Sounds like your AP nozzle is blocked.

Remove carb, make sure it's full with fuel, now it should have a nice stream of fuel when the throttle is applied. If it doesn't use a fine piece of wire to unblock the AP nozzle. Cut an old cable (throttle/push-bike) if you have trouble finding fine enough wire. I also used a pair of long nose pliers to assist in holding the wire and prodding the nozzle. In addition, I use fuel to soak it and compressed air to help blow the crud out.

I have had to do this to every carb I have ever bought (sec/hand).

Edited by Barra8

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Sounds like your AP nozzle is blocked.

Remove carb, make sure it's full with fuel, now it should have a nice stream of fuel when the throttle is applied. If it doesn't use a fine piece of wire to unblock the AP nozzle. Cut an old cable (throttle/push-bike) if you have trouble finding fine enough wire. I also used a pair of long nose pliers to assist in holding the wire and prodding the nozzle.

I have had to do this to every carb I have ever bought (sec/hand).

im a noob at carbs so can you please explain were the ap nozzle is and how to access it? thanks for your help

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Sounds like your AP nozzle is blocked.

Remove carb, make sure it's full with fuel, now it should have a nice stream of fuel when the throttle is applied. If it doesn't use a fine piece of wire to unblock the AP nozzle. Cut an old cable (throttle/push-bike) if you have trouble finding fine enough wire. I also used a pair of long nose pliers to assist in holding the wire and prodding the nozzle. In addition, I use fuel to soak it and compressed air to help blow the crud out.

I have had to do this to every carb I have ever bought (sec/hand).

oh and one more q ... its fine if i hammer it but at slow acceleration it does it at the one rev range.... ya reckon its still the ap?

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im a noob at carbs so can you please explain were the ap nozzle is and how to access it? thanks for your help

Rather than clog up this thread I will PM you. If Maniac doesn't mind I will post more on here.

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I've been searching & searching and believe my problem lies with a slightly rich needle condition in the transition from idle to mid-range, but wanted to ask you guys first.

Here's my symptom: Bike idles nicely, but stumbles/accelerates roughly thru the mid-range. On the first day of riding with the JD blue needle, it was incredibly hot & humid, and I thought for sure a switch to the JD red would cure the stumble, as per the charts recommendation. So a week later after switching to the red, I test drove it, and while it was nowhere near as hot & humid, the stumble was very much still there.

I have not done the Grey wire mod yet, so was wondering if this could be part of the problem?

ACV?

My bikes airbox is opened up and has an FMF factory 4 exhaust pipe, so it's definately breathing better than stock.

My jetting is as follows:

-Red JD needle 5th from top

-185 main

-72 starter

-40 pilot

-50 leak

-Fat O-ring on accelerator linkage

-2 out on adjustable air/fuel screw

Riding conditions in NY are:

1400' elevation

fairly humid lately 50% to 70%

temps in the high 80's

Please don't automatically move this over to the jetting forum, as I would like some input from fellow WR riders first. Thanks!!!

For a start your main jet seems large for your elevation. Considering that #168 is standard (US), I would try #180~ #183 main jet.

Other than that there is nothing unusual about your jetting.

Oh, if you have trouble, you can buy jets HERE.

Edited by Barra8

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Post all you want Barra, the more info the better! I've had incredible success with the JD jet kits over many, many bikes that's why I'm so perplexed with this one not working well. As for the main being possibly too large, I really haven't got a chance to really open it up since the mid-range isn't correct and all of my attention is focused on fixing that first.

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Post all you want Barra, the more info the better! I've had incredible success with the JD jet kits over many, many bikes that's why I'm so perplexed with this one not working well. As for the main being possibly too large, I really haven't got a chance to really open it up since the mid-range isn't correct and all of my attention is focused on fixing that first.

I have already told you the problem.

The main jet is too large.

Either adjust the jet needle clip position up or use a smaller main jet.

Because some people will say- ''no you're wrong!-

Check your manual, if you do not have one download it from HERE. Under ''tuning'' it will say

1/4~1//2 throttle:

Slow speed pick-up or poor acceleration = Raise jet needle clip position.

485562_583864938313648_1874691700_n.jpg

Enjoy!

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I got a chance to ride yesterday, and while the jetting changes I made weren't perfect, they were in the right direction and now the bike is running noticably better. The changes I made were to lean out the Main jet & lean out the Needle jet too. I know that you are supposed to do one change at a time to be able to document which change did what, but in reality that almost never happens! I had recieved a Quiet core muffler insert, so that had to be installed to quiet this thing down and I knew that the jetting would have to be adjusted for this too, so I threw it in and then changed the jetting as follows:

Main jet - 185 before, decreased down to 175

Needle - Raised the clip two notches, which leaned out the mid-range (JD Red needle/3rd from top)

Bike is waaaaayyyyyyyyy better now! Still not perfect, as there is the slightest hesitation/stumble as I crack open the throttle, but it is barely noticable and I will work on improving that another day.

Because today, I ride!!! :ride:

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Did you do the A/P squirt test?

You should have a nice steady squirt of fuel that just misses the slide and should go 3-5 ft.

That would explain the bog off idle that you experience.

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Did you do the A/P squirt test?

You should have a nice steady squirt of fuel that just misses the slide and should go 3-5 ft.

That would explain the bog off idle that you experience.

I have not checked that, but definately should verify that it's working properly. I really wouldn't call it a bog off of idle. It's more like an annoying, non-smooth acceleration if you will.

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