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Old 05-04-2010, 05:40 PM   #1
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Questions?? v-spec mid range needle on carb

Just wanting some info on the mid-range needle, how do you tune it, heard lots of people say just leave it flush and adjust the other 2 needles. I have messed with it about 3-4 hours each way and i can't tell a difference in any changes. just thought somebody on hear could help a little. thanks....
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Old 05-04-2010, 05:55 PM   #2
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lol, they told you right, flush at 2:00 and never mess with it again. Getting it wrong does way more harm than not having it perfect. Many high end engines do not even have a 3rd needle.
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Old 05-04-2010, 06:01 PM   #3
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If you need to ask, you shouldn't be messing with it. That's how I feel about the MRN. Leave it set flush and don't mess with it. I usually run mine flush at 11 or 12 O' clock, but 2 O' clock would be fine too.
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Old 05-04-2010, 06:50 PM   #4
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I have had 2 engines now where the mid range needle was tuned lean. One was sitting in my box for several months and the other went out to have some work done. The o rings feel tight but man was it off. When that needle is off the engine runs crapy. Personally I don't ever mess with them but I must have a ghost with a tunning driver that hangs out in my pit box. The one that was turned all the way in would not even run. It took me a little bitto figure out why and I reved it too much because the bearings went 2 races later. When the middle needle was all the way lean the engine just reved and then died. It would not idle and not run. Bottom line is don't mess with the middle needle and watch out got that damm ghost with the tunning driver
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Old 05-04-2010, 09:09 PM   #5
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Post mid range needle

let me shed some light on the subject as it was explained to me by several pro drivers .never ever touch the mid range needle unless your at the skill level of being able to tune an engine like say adam drake . when you adjust the mid range needle you will also adjust the low speed needle range in tandem ,any adjustments on the mid will be in 1/2 turns increments so the fuel feed hole on the needle will be lined up withthe high speed for proper fuel flow.if you turn the mid in or lean 1/2 turn the low will need to be richened or turned out the same .most racers will never notice the difference in tuning with the mid range even the pros wont adjust it ,they just check to see if the needles are lined up and leave it alone .ok so how do you check this, loosen up the high speed needle housing like your going to adjust the fuel nipple unscrew it completely look down into the chamber turn the mid range needle and you should see a hole on the needle this hole needs to be lined up so you can see the hole. turn it out or in so its centered in the chamber replace the high speed needle and tighten snug.do not touch again now go have fun and burn nitro
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Old 05-04-2010, 09:36 PM   #6
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Originally Posted by viperbill1963 View Post
let me shed some light on the subject as it was explained to me by several pro drivers .never ever touch the mid range needle unless your at the skill level of being able to tune an engine like say adam drake . when you adjust the mid range needle you will also adjust the low speed needle range in tandem ,any adjustments on the mid will be in 1/2 turns increments so the fuel feed hole on the needle will be lined up withthe high speed for proper fuel flow.if you turn the mid in or lean 1/2 turn the low will need to be richened or turned out the same .most racers will never notice the difference in tuning with the mid range even the pros wont adjust it ,they just check to see if the needles are lined up and leave it alone .ok so how do you check this, loosen up the high speed needle housing like your going to adjust the fuel nipple unscrew it completely look down into the chamber turn the mid range needle and you should see a hole on the needle this hole needs to be lined up so you can see the hole. turn it out or in so its centered in the chamber replace the high speed needle and tighten snug.do not touch again now go have fun and burn nitro
That makes a lot of sense as to why my engines that have had the middle needle messed with don't run the same after I get it close. I will do what you suggested. Thanks.
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Old 05-04-2010, 10:05 PM   #7
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Originally Posted by nitro crazy View Post
Just wanting some info on the mid-range needle, how do you tune it, heard lots of people say just leave it flush and adjust the other 2 needles. I have messed with it about 3-4 hours each way and i can't tell a difference in any changes. just thought somebody on hear could help a little. thanks....
The "mid needle" is what everyone else in the carburetor world calls a "spray bar". The movement of the spray bar puts it in the "sweet spot" of air flow when changing venturi, driving style and various other tuning capabilities.

Suggestion: 2:00 position from flush and leave it
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Old 05-08-2010, 09:38 AM   #8
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Is this refering to the needle on the side of the HSN or on the opposite side of the carb? The manual calls one the meetering needle and one the mixture control needle. Am i correct in assuming you are talking about the metering needle?
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Old 05-08-2010, 07:43 PM   #9
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Is this refering to the needle on the side of the HSN or on the opposite side of the carb? The manual calls one the meetering needle and one the mixture control needle. Am i correct in assuming you are talking about the metering needle?
We're talking about the one on the carb body, not on the slide. I'm not sure what the manual calls them, but the one on the slide is the Low Speed Needle(LSN) and the one on the carb body is the Mid Range Needle(MRN).
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Old 05-08-2010, 08:12 PM   #10
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Originally Posted by barrydidntknow View Post
Is this refering to the needle on the side of the HSN or on the opposite side of the carb? The manual calls one the meetering needle and one the mixture control needle. Am i correct in assuming you are talking about the metering needle?
Same side as the HSN just on the carb body.
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Old 05-08-2010, 09:04 PM   #11
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the manual calls it the mixture control valve. THe metering needle is the low speed needle.

i most certaninly see and hear the difference with just a quater turn. I sometimes use it to tweak my bottom end when i am having a hard time and get aggravated. and sometimes yes, it is just what the doctor ordered. But i never go more then a quater turn each way and i have the original setting marked on the carb body.

I look at it as cheating. If i was a really awsome tuner, i would do it fast and perfect with hsn/lsn. Because weather you use 2 or 3 needles, you still can equally end up in the same place. But on rare ocasions when i switch nitro or temp/humidity changes and i get a rich/lean bog that is giving me fits, the midrange needle will usually take it right out. And you can always go back.

It's a tuning tool. I say use it
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Old 05-15-2010, 01:01 PM   #12
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on my speed with the mid needle set at flush 2 oclock the hole does not line up with the hsn barrel so which is right ??
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Old 05-15-2010, 02:25 PM   #13
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the hole lines up on my ninja but not on my vspec.


my ninja is easier to tune fwiw.
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Old 05-15-2010, 07:04 PM   #14
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I have 2 jx ninja's that the hole lines up at 2 o'clock and my other 2 line up at 11 o'clock.
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Old 05-15-2010, 08:45 PM   #15
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jason, you going to be at watson when they open the new track?


your a very bad man with that losi!!
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