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Old 12-21-2002, 06:11 PM   #1
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Default resetting mixture control screw on hpi nitro rs4/3 type ss. Any ideas???

I need to set my mixture control needle/screw back to it's factory setting of 3 1/2 turns counter clockwise. The manual says i need to give full throttle then turn it 3 1/2 turn ccw. But do i have to screw the needle in fully then turn it 3 1/2 turns out or do it so it's flush and the do 3 1/2 turns, when it's at full throttle?

Any suggestions appreciated

Last edited by nigel1210; 12-22-2002 at 03:14 AM.
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Old 12-21-2002, 06:29 PM   #2
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Default low end needle

They mean you turn it ccw from all the way in/tighten. Be caraful not to overtighten it so you dont damage it. When you feel it stop then stop. Do not open the throttle then tighen it up all the way. You leave your throttle closed(at the idle postion), then turn it. It dosen't mean to turn it so its flush then go another 3 1/2 turns ccw. You should always tune according to how your engine runs, but following the directions is a good starting point so you can go from there. The low-end needle is hard to set, but once you get good at it you'll never want an engine without one.
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Old 12-21-2002, 06:33 PM   #3
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i've turn it all the way in till it stopped, the i turned it 3 1/2 times the other way(ccw), is that right???
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Old 12-22-2002, 12:40 AM   #4
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nigel1210;

Hold the screwdriver between two fingers and turn the (large) highspeed needle clockwise until it just stops. DO NOT force it any tighter. Reverse and open the needle counter-clockwise XX amount of turns as suggested in the kit manual.
Make small adjustments once you have the engine running and warmed up. No more than 1-2 hours (like a clocks hands) of adjustment at a time. ALWAYS adjust with at least 1/2 a tank of fuel or more and a fully warmed up engine.

Some of the R/C Car magazine websites have engine tuning guides for Viewing.
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Old 12-22-2002, 03:06 AM   #5
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Quote:
Originally posted by popsracer
nigel1210;

Hold the screwdriver between two fingers and turn the (large) highspeed needle clockwise until it just stops. DO NOT force it any tighter. Reverse and open the needle counter-clockwise XX amount of turns as suggested in the kit manual.
Make small adjustments once you have the engine running and warmed up. No more than 1-2 hours (like a clocks hands) of adjustment at a time. ALWAYS adjust with at least 1/2 a tank of fuel or more and a fully warmed up engine.

Some of the R/C Car magazine websites have engine tuning guides for Viewing.
yeah i've already done that, i'm trying to set the low end needle. any ideas
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Old 12-22-2002, 09:56 AM   #6
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any suggestions
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Old 12-22-2002, 10:50 AM   #7
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The low end needle is very small and is easy to damage, This is the reason for opening the throttle BEFORE adjusting the needle. Open the carb to full throttle, then turn the needle cw until it stops (do not force it), then turn ccw 3 1/2 turns. This is factory setting.
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Old 12-22-2002, 11:54 AM   #8
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Default Needle setting

nigel1210;

You must set the High end needle first (you said that) then adjust the low speed needle so the engine response is crisp and it will sit idling for at least 30 seconds with out stalling. Sometimes it is nesessary to run a slightly rich Idle to keep the engine running cool, but that is usually when racing Off-Road.
Use the "Pinch" test to check your low speed needle setting. Once you think that you are close to where it should be. "Pinch" the fuel line closed, next to the carb nipple and the engine should stall with almost no change in rpm. A very slight increase as it stalls should be about perfect for the average engine.
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Old 12-23-2002, 04:11 PM   #9
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yup pops racer is correct. Main must be set first then lowend then idle. Another way of testing if your low end is correct is the odle test. I find it works better but that is my opinion.

To do the idle test do a speed run(after main is set). Then after you get to WOT and you're at top rpm let it come down to an idle. Let it idle for about 5-7 seconds then NAIL the throttle. Thatrs right, give it WOT and nothing but. The take off will tell you whats up with your low end. If it bogs, 4-strokes a little, or makes big puffs of smoke and looks like it is stuggling to get to speed then your low end is set too rich. In that case you lean about 1/8 of a turn maybe more maybe a little less. If you nail it and it misses or almost quits then you are too lean. A overly rich low end wll make your car load up very fast. A too lean of a lowend can make an engine idle unsteadily make it (speed up and slow down) and most importantly it will cause it to overheat.

Pops mentioned that it should idle for at least 30 seconds. That is correct for hard running and or bashing. I myself set mine to just idle much much longer than that. I do that so if it gets stuck on something, I dont have to blimp the throttle to keep the chamber from loading up. It's also fun to let it idle for a min or 3 and then nail it and it takes off very strong without bogging or missing. Yes it does smoke alot but it takes of like crazy fast. Another advatage, you can put your body on or set your shift point or do other minor things and not have to worry about it stalling. But do go for atleast 30 seconds. Be very patient too. Make sure your engine is up to proper engine temp before attempting to tune it. After you make a needle adjustment, run it a little while to let the new setting work. Even if it takes you days worth of running, tune untill youve got it right. there isnt anythign more frustrating then having a engine running bad and having to tune everytime you run it. Tune it right and forget about it.
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Last edited by TheRagunCajun; 12-23-2002 at 04:15 PM.
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