07 WR 450 stalling when opening throttle fast

[yam90]

I have owned an 04 and currently own an 06 WR450 and now I have recently bought an 07. I removed the air induction as usual and made some jetting adjustments. Now when I open the throttle fast from an idle the bike stalls out. If I slowly open it a bit from an idle and crack it open it works fine. I pulled the carb off my 06 (as it works perfect) and when I installed it on the 07 it does the same thing, dies if throttle is cracked from an idle. I also swapped the carb from the 07 onto the 06 and the 06 runs fine with it. If anyone has any idea what can be causing this bike to die I would really appreciate it. You can only imagine how frustrated this is making me ..... :applause:

[clark4131]

You have the Keihin off-idle bog and need to tune and jet your carb properly. Read your manual regarding the Accelerator Pump, look through the jetting database, and search the archives for "bog". That ought to give you lots of info on how to fix your problem. Also, if you're testing it in the garage, you'll never get an accurate feel for what's going on. The bike must be ridden and up to operating temps in order to determine if your tweaks are right...SC

[Indy_WR450]

no two motors are the same. your 07 is having a lean bog. try my zero jet solution. take the stock leak jet and silver solder it shut.

[jams229]

Indy, them are a lot of posts!

[Indy_WR450]

Indy, them are a lot of posts!

Yeah I try and keep the posts to useful technical help only.

I am tempted to start over soon as Indy TE610 as I will be buying a new Husky in 2008:ride:

[sts475]

Good Luck with the TE610 purchase. Choose the bike and the dealer carefully.

Trust me on this one...........

STS.

Yeah I try and keep the posts to useful technical help only.

I am tempted to start over soon as Indy TE610 as I will be buying a new Husky in 2008:ride:

[Jammer]

Maybe an accelerator pump cover will work - I was checking them out on the weekend, and they are supposed to give an extra shot of fuel off the bottom when you open the throttle. Boyeson makes one (as do others), but Factory R&D makes them model specific, whereas I guess all of the others are universal. Someone with more experience on this topic may be able to enlighten us more.

Some MX shops sell a lot of them.

[bigbully]

Don't bother with the pump cover. A larger leak jet does the same thing for a fraction of the cost. I wish I would have known before I bought my Boyesen.

[Fullbore4]

Don't bother with the pump cover. A larger leak jet does the same thing for a fraction of the cost. I wish I would have known before I bought my Boyesen.

Like Indy_450 recommended, going smaller on the leak jet (even soldering it shut-making it a 0 jet) will help richen the AP squirt which is needed here. What a boyesen does is gives an instantaneous squirt upon just hitting the throttle which is needed to remedy the infamous momentary lean condition of the FCR carb. A caveat of the boyesen though is it then continues to squirt gas causing a rich condition after the slide opens sufficiently. The Scary Fast Powershot claims it does not richen the "post-mix" like the quickshot, but my experience with it shows it does not act as instantaneously as the Quickshot and hence leaves a little bog upon hitting the throttle. I am going back to the Quickshot because I have a BK mod on my bike and I cut the AP squirt duration to 0.2 seconds which satisfies me the most. I like it feeling this way but maybe others don't. Most just put up with a little bog or don't know they have one. They don't have a quickshot or they have a quickshot but the leak jet/diaphram/jetting combination is not set up right.

[Jammer]

I knew someone would know about it!

Thanks for all the info.

[CRF45OX]

What if you use the quickshot and just change the leak jet so it dosent get too rich - because the quickshot is meant to make the carbys work how the should - not have an air pocket in the chamber - ive heard the throttle response is awesome with the quickshot - thats a main advantage of them.

[Greenroom]

I installed the quickshot when i removed the AIS and I'm very pleased. The quickshot along with adjusting the air-fuel mixture screw correct has the bike very snappy.

[Fullbore4]

What if you use the quickshot and just change the leak jet so it dosent get too rich - because the quickshot is meant to make the carbys work how the should - not have an air pocket in the chamber - ive heard the throttle response is awesome with the quickshot - thats a main advantage of them.

I think your right but the question is which leak jet combo is the right one. Greenroom happened to get the right one it appears. The mods I have done including using a 0 leak jet, leave no question as once my AP is adjusted correctly, I just adjust the BK mod screw shown at the red arrow.