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Removing the lurch from a YZ250FX ?

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On 10/25/2018 at 5:54 PM, revindevin said:

Lol yeah it can be intense at times. If a $70 fuel line improvement can fix it I'm all in. Still waiting on the site to get back to me because the site no longer lists the part for yamaha.

I have that fuel rail installed on my bike.  I tested it for Dave last spring.  While it does help some to remove a bit of the jerkiness on/off idle, I felt it was not worth the risk/hassle of installing it.  Plus, as I have posted time and time again, if you use your clutch properly you will learn to love the quick throttle response the FX delivers.   To get to the fuel rail on these bikes, you have to remove the gas tank and air box.   The gas tank is no problem, but removing the airbox is a bummer if the bike was ever ridden on muddy days..  The reason being it is almost impossible to not get dirt dropping into the throat of the throttle body. If your bike is brand new, no problem.  But, if it has been ridden on muddy days, your bike will have dirt in between the frame and airbox that is impossible to remove before you take the airbox out of the bike. When you lift the airbox out, the dirt drops right into the then exposed throttle body throat.   If you have a surgical suction tool, no problem, but I don't.  So, I had to get creative to get the dirt out of my throttle body, and it was a bit of a hassle.  Again, IMO,  small gain not worth the risk/hassle of the install.

Edited by Shredjim
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On 10/24/2018 at 6:20 PM, Honeybagder said:

The trick is to not use 1st gear ever and use second gear sparingly...

Gearing on the 250FX is prety much the same as my 16 TE300s was.

1st gear is only used in the tightest stuff possible,3rd gear on most singletrack.

I have no issues with a lurch....power is pretty tame 

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No lurching. Super tractable and still rips

BRM Map

FUEL         IGNITION

1, 2, 3            0, 2,  3

2, 2, 2           -1, 1,  3

2, 2, 2           -3, -2, 1

   I run this on my WR 450 and YZ250FX

Very controllable and plenty of power

Basic tuning is better bottom end with more fuel and retarded timing. Top end advanced ignition timing and fuel to suit conditions.    

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7 hours ago, Shredjim said:

I have that fuel rail installed on my bike.  I tested it for Dave last spring.  While it does help some to remove a bit of the jerkiness on/off idle, I felt it was not worth the risk/hassle of installing it.  Plus, as I have posted time and time again, if you use your clutch properly you will learn to love the quick throttle response the FX delivers.   To get to the fuel rail on these bikes, you have to remove the gas tank and air box.   The gas tank is no problem, but removing the airbox is a bummer if the bike was ever ridden on muddy days..  The reason being it is almost impossible to not get dirt dropping into the throat of the throttle body. If your bike is brand new, no problem.  But, if it has been ridden on muddy days, your bike will have dirt in between the frame and airbox that is impossible to remove before you take the airbox out of the bike. When you lift the airbox out, the dirt drops right into the then exposed throttle body throat.   If you have a surgical suction tool, no problem, but I don't.  So, I had to get creative to get the dirt out of my throttle body, and it was a bit of a hassle.  Again, IMO,  small gain not worth the risk/hassle of the install.

Thank you very much for the info. I really enjoy working on my bike. I might like the task of pulling it apart haha. I actually do have a suction tool believe it or not haha. But I completely see your point. The vast majority of the time I dont feel any issues from my bike. Matter of fact with the way I have it set right now I have never been better on a bike. It's more because I have been riding my kids around and been noticing the jerky feeling. I use my clutch and smooth it all out, but would prefer less stress and wearing on it if possible.  

One note. I cut my back fire screen out and that seemed to do more for it than the exhaust. 

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