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Discussion Starter · #1 ·
Anyone with 250x with pipe Fmf programmer and airbox lid off have any good numbers for the programmer. I have the Steveakus numbers seeing if anyone had anything different that they either had dyno tuned or butt tuned just looking for other opinions now that alot more people have done this... thanks in advance
 

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I have played around with the programmer quite a bit when I first got it. Nothing is better than what you are currently using for your setup. You are not going to get any more out of the bike.

I also have a full exhaust and the airbox lid off and I am running the same numbers as you.
 

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Discussion Starter · #3 ·
how long have u used those numbers i was just worried about it running lean since i opened up the box...guess it is good dont worry about it?
 

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I have used those numbers since Sept 2010. I went with a full system because I like the look better. I don't think the WR is like the DRZ in the sense that the header chokes the shit out of the DRZ. Lots of guys just have a slip-on and have done what you have and run the exact same setup. I wouldn't worry.
 

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3.5-4.5-1.5-8-4-4.5

I change between 4 and up to 5 on the second number.
Seems colder temps do better with 4 and higher temps do better with 5.
 

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3.5-4.5-1.5-8-4-4.5

I change between 4 and up to 5 on the second number.
Seems colder temps do better with 4 and higher temps do better with 5.
Just put these numbers in. I'll see how I like them.
 

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Discussion Starter · #8 ·
should be the oppisite way around colder temps normally mean thinner air thus more fuel and higher temps normally mean thicker air thus means leaning it out....
 

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its the ideal gas law.

it says as temperature goes down, in the same volume of "air" it becomes more dense.

as temperature increases in the same volume of "air" it becomes less dense.

so when as temp increases molecules get more excited and more around/spread out more.

as it decreases they become less excited and are around more.

granted i have not taken chemistry in a long time, but pretty sure this is how it works
 

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unless of course you are equating cold air to altitude? then pressure would be changing, which would mean less pressure, less dense, and inversely colder gas so colder air and vise versa for lower altitude.

again my chemistry is old so i may not be remember right.
 

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Discussion Starter · #13 ·
lol im lost. All i know is when i use to race motorcross... If it was hot out i would lean the bike out because the air is thicker muggier whatever you want to call it in florida. When it was cold out i would fatten the bike up a little because the air was thinner.. Not aruging or being a prick but even if you ride on a cool night in whatever you own almost always seems like the bike or car runs better especially if you have a cold air intake on a car
 

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^^ your correct, same for why snowmobiles run a lot better as the weather gets colder, and once it gets near 40 degrees or so they start to run like shit. if you lean them out to much cuz its warmer out then run um in -15 degree weather they dont last long before popping. your idea is correct but i have no clue on the physics side of it.
 

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Here I will explain some of the physics... in case someone cares. Air is just a bunch of molecules bouncing off of eachother and their temperature corresponds to the average speed each of the air molecules carries. If a gas is "hot", the average speed of the particles is greater than that of a "cold" gas.

Now Imagine all these particles bouncing off of eachother randomly. If they have a higher average speed (hotter) then there must be more collisions between the molecules. This causes them to move further away from eachother and take up more space, or an increase in volume, if they can. This means that compared to a cooler gas, there are fewer gas particles in a given volume because the hotter gas has them more spread out since they are hitting eachother hard and pushing outwards.
i.e. when your tires get hot from sitting in the sun or agressive riding, the psi increases because the air molecules are gaining more energy and are hitting eachother harder. They want to push out more.

Now if they are more spread out and your engine always breaths in the same volume for each intake stroke then with a hotter gas there will be less air molecules present than if the air was cooler.

Now how does an engine make more power: 1) extract energy from the combustion process more efficiently 2) Shove more fuel and air into the combustion chamber and make a bigger boom.

Simply put, cool air is more dense than hot air so more air goes into your engine when it is cooler out. And if your engine is running a little rich with hot air, it will run better with cooler air because there is more oxygen to match the extra gasoline.
 

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Discussion Starter · #17 ·
ok thats waht i thought cause fjoel said 4 works better in colder temps and 5 better in higher temps. So thats why i was aruging the point it should be the opposite way around his bike should run better at 4 in higher temps and 5 in colder temps to compensate for the air. no biggie
 

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Its over 100 degrees here right now. I can feel the 4.5 in the middle is too fat. I can be holding the throttle pretty steady then as the revs drop a little bit it all of a sudden takes more throttle to hold my speed. Probably just this sweltering heat though.
 
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