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After changing exhaust systems on my 18 250X my fuel consumption has gone from 90km per tank to 30km per tank. I have done the jetting and the power is good. There is quite a bit of spoodge, can any help with ideas ?

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pipe and jetting?  

If you went with the pipe manufactures jetting settings you are probably quite fat on the main.

I think FMF recommends a 180 on the main to start

Edited by subxero

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Not related to the pipe change but check / adjust the float's height, known to be off even on brand new bikes.

 

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I feel like there is something else at play here.  If you JUST changed the pipe, it should not have any significant effect on fuel consumption, regardless of which pipe you installed.  Did you touch anything in the carb?

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pipe and jetting?  
If you went with the pipe manufactures jetting settings you are probably quite fat on the main.
I think FMF recommends a 180 on the main to start

Thank you, I have worked my way down on the jetting as the recommended 180 was to rich. I will strip and check float levels as well as needle setting.
I can’t find any cases of the fuel consumption getting this bad.

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Not related to the pipe change but check / adjust the float's height, known to be off even on brand new bikes.
 

Thank you, I will check it tomorrow.

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I feel like there is something else at play here.  If you JUST changed the pipe, it should not have any significant effect on fuel consumption, regardless of which pipe you installed.  Did you touch anything in the carb?

Hi Doc,
I went with a FMF header and silencer and worked with the jetting and adjusted the needle one clip down. Thinking maybe I should go back to Std and check consumption

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That is quite a bit of difference. I would do the 40 leak, and suggest bring all settings on carb back, see if it runs good. Go from there. Something is off to consume more. 

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11 hours ago, Nick.T said:

...fuel consumption has gone from 90km per tank to 30km per tank...

Your kpl was reduced by two thirds. Let's write this out...

Before mods, you covered 90 kms (55 miles) with 8 liters (2.1 gals) of gas. (approx.)

After mods, you traveled 30 kms (18 miles) with 8 liters (2.1 gals) of gas. (approx.)

That is astounding. A change that dramatic should have you looking for a fuel leak. Next would be to question the testing procedure.

Just for reference, our 250s (YZ & CR) get around 45 miles per tank (woods/trails). We have run them dry at about 48 miles. I think that is what most 250s get. (Other riders may feel free to chime in.)

55 miles on a tank (admittedly, you're riding an X) would be inconceivable to us.

I'm not questioning the validity of your results; it just seems too radical of a change for just pipe & jetting to cause. Headscratcher. :excuseme:

Edited by CaptDan
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Your kpl was reduced by two thirds. Let's write this out...
Before mods, you covered 90 kms (55 miles) with 8 liters (2.1 gals) of gas. (approx.)
After mods, you traveled 30 kms (18 miles) with 8 liters (2.1 gals) of gas. (approx.)
That is astounding. A change that dramatic should have you looking for a fuel leak. Next would be to question the testing procedure.
Just for reference, our 250s (YZ & CR) get around 45 miles per tank (woods/trails). We have run them dry at about 48 miles. I think that is what most 250s get. (Other riders may feel free to chime in.)
55 miles on a tank (admittedly, you're riding an X) would be inconceivable to us.
I'm not questioning the validity of your results; it just seems too radical of a change for just pipe & jetting to cause. Headscratcher. :excuseme:

I agree capt.
it’s a mind blower, I cover between 80-90km Forrest riding at slow to med pace which is why the change is just crazy. I am going to go back to stock and monitor from there.

There is definitely no leaks I have triple checked that.
That is quite a bit of difference. I would do the 40 leak, and suggest bring all settings on carb back, see if it runs good. Go from there. Something is off to consume more. 

I will keep you posted on my findings threw the week.
Thank you
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The nice thing about this is that you have a fresh, solid bike as a starting point. You KNOW how it should perform, and you know nothing "broke"; heck, that bike is new!

So we're expecting a good report. :worthy: :prof: :thumbsup: :ride:

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Carb is now stripped, according the the Machanic working on it:
- Float levels are way out
- needle is in center clip (STD)
- he wants to lean the jetting out slightly currently running a 176 main.
- putting a hotter plug as well. Then time for testing

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