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Discussion Starter #1
Hey everyone,

Last winter I readjusted my values, then in the spring this year I jetted (#25 160/165) and added powerbomb headers to complete my full exhaust. I had a slip on already. When I first set it all up, it started instantly, it ran for about 3 or 4 rides like a champion for about an hour each ride, amazing throttle response and everything. The other day I was riding and it randomly started sputtering, I couldn't put my finger on exactly when it would do it, it seemed random. So I took it all apart again and readjusted my air fuel to 2.5 turns (I had it at 2.75) and it is still randomly sputtering. Also it idles just fine. Anyone have any ideas? I don't think its my air fuel but I could be wrong, I just don't understand why it would run so great for so long then randomly have an issue.

Side note, I cleaned my fuel filter, which wasn't even dirty. I also sometimes have what people call "after fire" which may mean something to all of you. When I turn my quad off, about 75% of the time theres a faint woosh sound from my exhaust, I've read that it could be fumes being ignited in the bend at the headers after the engines off.
 

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Discussion Starter #2
Another update, it appears that its only happening when i open the throttle wide open. And its cutting out, not really sputtering.
 

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Are you hitting a rev limiter? 160-165 mains could be too rich if you aren't running an open airbox.
 

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Discussion Starter #4
It is a closed air box, and it was running great for a few rides. I was wondering if it was lean or rich, i dont think it was rich though because if i cup my hand behind the muffler it doesnt smell like gas, at all.
 

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I am unique
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It is a closed air box, and it was running great for a few rides. I was wondering if it was lean or rich, i dont think it was rich though because if i cup my hand behind the muffler it doesnt smell like gas, at all.
A rich mixture doesn't mean that the unburned fuel or rich mixture will magically fall out of the exhaust pipe. Rich mixtures run colder and create more pollution and black smoke.
 

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Discussion Starter #6
Rich mixtures run colder
It seems like its running a lot hotter than normal, or maybe its because i dont have heat shields on anymore for my pipes. Are there any dangers to engine damage if i crank up the air/fuel to see what it does? I've been told that rich is ok for an engine, and that lean does damage.
 

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It seems like its running a lot hotter than normal, or maybe its because i dont have heat shields on anymore for my pipes. Are there any dangers to engine damage if i crank up the air/fuel to see what it does? I've been told that rich is ok for an engine, and that lean does damage.
On a two stroke you definitely don't want to run lean.
Four strokes are much more forgiving.
I'd worry more about getting the proper fuel air ratio then pipe temperature.
 

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Master of the Electron
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Run 150L/155R - You're too rich with a closed airbox.
 

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Discussion Starter #9
Run 150L/155R - You're too rich with a closed airbox.
I think your onto something, i took my lid off and rode up and down the road full throttle with out one single cut out. So i guess that leaves me to either taking off my lid or getting new jets to work with a closed box.
 

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Do you have aftermarket needles? my jetting is in my sig, mine runs perfect at the moment lol
 

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Discussion Starter #11
Do you have aftermarket needles? my jetting is in my sig, mine runs perfect at the moment lol
Nope, i still have stock needle. Someone on a video said the stock needle is more than anyone will ever need unless your running alcohol fuel. Perhaps he was wrong.
 

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Nope, i still have stock needle. Someone on a video said the stock needle is more than anyone will ever need unless your running alcohol fuel. Perhaps he was wrong.
He is wrong.
 

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Needles control how your fuel is delivered. They are responsible for any throttle under about 3/4. When you increase the airflow, you need more fuel. You cannot quite get the proper ammount in the mid throttle range on stock needles, no matter how much you change jets and fuel screw settings.

You will see better responsiveness and smoother revving.
 

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Master of the Electron
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ABSOLUTELY wrong! It's very hard to tune an open airbox without the more aggressive taper of aftermarket needles.
 

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I recorded a video today of my throttle response ill try to upload it tomorrow... my bike runs perfect..

I also did the clear tube mod and modded the floats
 

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What else did you do?
This thread is over 5 years old. Start a new thread and tell us what your problem is. Dont forget to mention any mods you may have

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