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Old April 16th, 2010, 05:11 PM   #1
Thrak
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Air cut off valve

Has anyone removed the air cut off valve from the carbs? If so, what are your impressions?

Thanks!
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Old April 16th, 2010, 08:06 PM   #2
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what's an air cut off valve?
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Old April 17th, 2010, 06:57 AM   #3
Thrak
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Its the little valve on the left of the carbs, works kind of like the petcock with a little diaphragm. It injects (or not) air into the carbs under certain conditions.

I'm not sure what those conditions are, or what its purpose is. Emissions?
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Old April 17th, 2010, 11:32 AM   #4
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I think that's the coasting enrichener.



http://faq.ninja250.org/wiki/How_a_c...a_Closed_Mouth
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Old April 17th, 2010, 11:55 AM   #5
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Quote:
Originally Posted by kkim View Post
I think that's the coasting enrichener.
You are correct. It is also called an air cut off valve by some. It's purpose is to reduce popping when you close the throttle at speed. I don't know of any performance advantage by removing it other than saving a couple ounces of weight. I've seen a lot of 250 Ninja race bikes over the years and all the stock carbs have had the coasting enrichener left in place.
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Old April 17th, 2010, 12:11 PM   #6
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from what I've read in that link I posted, I don't know why you would want to remove it.
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Old April 17th, 2010, 01:28 PM   #7
Thrak
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My bike will never be on the street.. so things that benefit street riders (like a coasting enricher) are of no use to me. Hopefully, I'll never be coasting.

Also it seems like this may make it more difficult to fine tune the a/f mixtures screws. Rev it up and see how it comes back to idle but this adds fuel, making the mixture not entirely dependant on the a/f screw setting.

Or, does this thing only come into effect during engine braking?
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Old April 23rd, 2010, 04:32 PM   #8
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So I removed it today and it made a HUGE difference.

It starts up in less than a full crank and it "idles down" so much faster.

May not be the best mod for the street cuz it did introduce a very small amt of off-throttle popping, but its not a big deal. The positives far outweigh the negative for me.
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