My WR is idling irregularly...

I bought an 06' WR450f about a month ago and had it out for the first time last weekend. After riding for a few hours I noticed that it was not running right at low speeds and during idol.

What's happening is after reving the engine the bike stays at a higher RPM for several seconds instead of dropping back down to the normal idol RPM. It doesn't look like the throttle is sticking so I'm wondering what else it could be ?

Any advise would be greatly appreciated as I'm trying to avoid taking it into a local dealer for a $100 diagnostic !

Justin

SLC, UT

Open the fuel screw a turn or so (no more than 3 from fully closed though)

Open the fuel screw a turn or so (no more than 3 from fully closed though)

x2 ----Sounds like it is lean at idle

If you haven't changed anything, then you have a clogged pilot circuit...time to clean the carb. If you've changed things, then you need a larger pilot jet...SC

I bought an 06' WR450f about a month ago and had it out for the first time last weekend. After riding for a few hours I noticed that it was not running right at low speeds and during idol.

What's happening is after reving the engine the bike stays at a higher RPM for several seconds instead of dropping back down to the normal idol RPM. It doesn't look like the throttle is sticking so I'm wondering what else it could be ?

Any advise would be greatly appreciated as I'm trying to avoid taking it into a local dealer for a $100 diagnostic !

Justin

SLC, UT

Dude, I see that you are new so thanks for comin and in case you aren't sure about the location of your fuel screw check out this pic

attachment.php?attachmentid=299&d=1132119988

What you see here is the bottom of your carb after it has been pulled away from the head. The red thing on the left is an aftermarket fuel screw which makes adjustment using your fingers possible. Dunno, but maybe the previous owner modified it already. If so, you should be able to reach it and adjust it as has been recommended . If not, you will have a recessed screw in this location that will require you to get a screwdriver on it. Good luck and I hope that you aren't already aware of all of this....I shoulda asked:banghead: In addition you may want to investigate the Tech Arcticles and Tips Section (the place that you posted an identical thread) and check the Intake/Carb threads- FCR carb...heres a specific video link rejet FCR but there are many more threads to read that may help you dig into your carb. They are not all that complex after you read up on em.....These bikes have been runnin the same carbs for a while so try using the advanced search tab and it should give you more info than you can read in a day.:applause:

Thanks to all that replied. I have few possible solutions that I'm going to research a bit further. Probably start with the fuel screw.

Cheers !

righto with the fuel screw replace your main jet it will be worn, my bike did the same thing as your put a new main jet in went sweet even got rid of the back firing

I bought an 06' WR450f about a month ago and had it out for the first time last weekend. After riding for a few hours I noticed that it was not running right at low speeds and during idol.

What's happening is after reving the engine the bike stays at a higher RPM for several seconds instead of dropping back down to the normal idol RPM. It doesn't look like the throttle is sticking so I'm wondering what else it could be ?

Any advise would be greatly appreciated as I'm trying to avoid taking it into a local dealer for a $100 diagnostic !

Justin

SLC, UT

You never said if you've removed the AIS or not. I had the exact same indications before I did the mods (IE removing the AIS) since then, all is well.

Hey, Dirty South...not to hijack the thread or anything, but was that Boysen cover worth the money? Would you reccomend it to others, or what? I'm considering getting one, if it does what it's supposed to.

Hey, Dirty South...not to hijack the thread or anything, but was that Boysen cover worth the money? Would you reccomend it to others, or what? I'm considering getting one, if it does what it's supposed to.

Sorry dude but I robbed the pic from another post for reference. You can certainly search for Boyeses accelerator pump and turn up a lot of info as guys were posting frequently at one time when this AP cover had come out. However, the gains were not good enough to warrant my purchasing one. I have found that merge racing is making an accelerator pump that is much more advantageous as it has an adjustable leak jet and the option for a stiffer spring. Heres a link..Merge ALJ..click the buy tab to see the improved spring and relative prices:smirk:

You never said if you've removed the AIS or not. I had the exact same indications before I did the mods (IE removing the AIS) since then, all is well.

I haven't done any of the mods. AIS is first on my list though. I think the plan of action now is to remove the AIS, clean the carb and jets and possibly adjust the fuel screw...if needed. Now all I need is a free night to work on my bike...

AIS will not affect the jetting at all, unless there is a vacum leak.

Main jets do not wear, needle jets do though from the needle action sliding up and down.

This is just an update to this post. I went through the carb and put a new pipe on this bike a few months ago and now it's running perfectly. I think dirty carb/jet was the culprit !

I changed the leak jet and put on the Quickshot2 cover and rid myself of an initial studder that I got with the JD needles. They definitely helped. I have since started using the JD needles to poke my pipe with and run the YZ450 needle in my carb. :lol:

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