Some advice please

  #1  
Old 09-13-2018, 12:13 AM
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Default Some advice please

hey everyone new to the forum just need some help. I just bought a 2018 KLX250 250sj and want more *** I order a barker exhaust and ejk controller. Do I pull snorkel or take lid off completely?
 
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Old 09-14-2018, 03:08 AM
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You take the lid off the airbox, take it to a dyno shop, tell them you want 12.75:1 for all WOT operations. 13.8 - at low loadings/throttle ops tapering down to 13.2:1 for higher loadings and throttle settings - then taper down to 12.75 as throttle settings go beyond 60% - with 12.75 being hit by 85% throttle position..

They may protest the part throttle fueling I suggest - and if they really know what they are doing, it's ok for them to "do their thing" in that RPM/throttle/loading range..That area is concerned with driveability and fuel mileage only.. However, 12.75:1 for all wide open throttle operations is non-negotiable..

Believe it or not, many "tuners" are complete morons - E.G. With no knowledge of how AFR affects flame front speeds.. Ask your tuner what they think your lidless airbox and barker exhaust will do to your engines' VE - see how they respond.. (VE = volumetric efficiency, but they might even know THAT! ).. A correct response would be something like "typically, those mods will significantly enhance VE in the upper 1/2 of the RPM range at WOT but the cams will determine the exact results"..

P.S.
Anywhere VE is enhanced (over stock) additional fueling would be required..
Assuming you have the full Barker exhaust system, and if they do your tune right, your bike becomes an "animal" compared to before...
 

Last edited by Klxster; 09-14-2018 at 03:42 AM.
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Old 09-14-2018, 05:46 PM
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Yes many are dumb asses I agree! I do have full barker exhaust.
Should I just block the pair valve where it hooks to head then block the hose I just pulled out?
thanks for the info!
 

Last edited by Kris250; 09-15-2018 at 12:26 AM.
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Old 09-15-2018, 12:32 AM
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One more bit of advice... If someone says " just one more drink", don't do it. You'll just wake up wondering "How did I get here? And where are my pants?"
 
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Old 09-15-2018, 01:03 AM
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Been there. Lol.
 
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Old 09-19-2018, 01:05 AM
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Those afr you give me did you test with them? Are they for carb or efi?
 
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Old 09-19-2018, 02:57 AM
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Yes, my testing settled on those targets. That is probably all you wanted to know, so I'll not elaborate..

Carb or EFI ? This question makes no sense - The type of fueling system is irrelevant..

To talk any deeper about AFR will probably be counterproductive.

Just remember, most "tuners" are not the sharpest tools in the shed. Ask your friend/tuner/etc - What is the relationship between AFR and ignition timing ?

P.S. The right answer is that richer AFR's require less ignition advance, leaner AFR's require more ignition advance.
 

Last edited by Klxster; 09-19-2018 at 03:10 AM.
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Old 09-20-2018, 12:43 AM
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That’s what I thought but the guys at work had me convinced carbs need to be richer than efi
guess they are the dumb asses
 
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Old 09-20-2018, 01:25 AM
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Originally Posted by Kris250 View Post
That’s what I thought but the guys at work had me convinced carbs need to be richer than efi
guess they are the dumb asses


Yep, complete dumb asses... But dumb asses usually have dumb *** reasons for their dumb *** advice - which could be really funny to hear...?

Just a little primer : AFR = air fuel ratio. 12.75 : 1 - 12.75 parts air to 1 part fuel. Whether that is being created by EFI, carbs, or spraying fuel out a spray bottle into the intake tract, it's all the same to the engine..
 

Last edited by Klxster; 09-20-2018 at 01:39 AM.
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Old 09-20-2018, 06:27 PM
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Would you recommend the same AFRs with a 351 big bore?
 

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