ys91 tuning - HeliFreak
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Old 04-13-2004, 02:58 PM   #1 (permalink)
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Join Date: Apr 2004
Location: OH
Default ys91 tuning

I aquired a ys91 second hand and it has approx 4-5 gallons through it running on a mp2 in a raptor 90(8.45 ratio) Im having some issues tuneing it and wondered if anyone can share their needle settings. If your from Ohio...all the better!!!

"Take a prozac and enjoy the hobby"

Hirobo Evo, OS 50 hyper/MP2Q
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Old 04-13-2004, 03:10 PM   #2 (permalink)
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Join Date: Mar 2004
Location: Birmingham, AL

Needle settings will vary according to atmospheric conditions.
Here is my settings using Cool Power 25% fuel with 17% HV oil.
Also I have a Viperhead on the motor which allows the needles to be a couple of clicks leaner.
I am using Hatori SB 16 and 7.75 to 1 ratio in Tempest.

Mid Range needle ( long one) 1 3/8 turns open from fully closed
High Needle ( short one) 3/4 turn open from fully closed
Low end The needle is just about flush with carb barrel. I didn't mess with it, but I believe it is like 1.5 turns out from fully closed.

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