steve9534
01-01-2006, 10:35 PM
Will has been kind enough to keep this site going and has asked for some more content, so here goes. Most of the folks here have a fair bit of experience and probably don't need this, but just in case someone new happens to stray onto the site, here's how I set my needles.
In order to get the motor started, you need to start with the manufacturers settings. Unfortunately, most don't give you any indication for how to adjust the low end needle, so what to do? First open the high end needle the recommended number of turns. Now set the idle throttle point so that the carb is open about 1mm, hook up some tubing to the fuel inlet and blow. Adjust the LOW (NOT high end, it's important you figure out from the start which is which) end needle so you can just barely blow through the tubing and you can hear air passing into the carb inlet. Now fill the tank and start the motor. Assuming it starts, then adjust the throttle ATV to give a slightly higher than normal idle. If it won't start, then open the throttle little by little until it's no more than 1/4 of the way open and keep trying. Make sure you have a good hold of the head as you do this so it doesn't take off and make hamburger out of your arm. Keep the radio on and be ready to turn the throttle down as you do this. If it still won't start, then your either too rich or too lean. By this point, if it's rich you've probably got some fuel spitting out the exhaust and you need to start leaning the low end needle 1/4 turn at a time until it does start. If it's too lean, then the exhaust will be dry, or very nearly so, and you need to start opening the low end needle 1/4 turn at a time. Once you get the thing running and the ATV set for a reasonable idle, you can further tune the low end needle by pinching the fuel line and if the motor speeds up somewhat for about 3-5 seconds before dying, you're about right. If the motor just dies straight away w/o speeding up, it's too lean, and needs to be richened up, if it speeds up a lot before dying, it's rich and needs leaning out. Next adjust the ATV for a nice slow idle.
Now it's time to fly. With the low end set and the high end at the recommended # of turns, it should hover OK. More than likely it will be a bit rich as the manufacturers tend to err on the rich side with their recommendations. If it's rich, just leave it alone at this point. If it's lean, it may run rough, but the #1 thing to look for is if it immediately drops into a nice low idle when you set it back down. Any running on, ring-dinging, or hesitation in going back to idle indicates the motor is running hot and the needles need to be adjusted richer accordingly. If you've got a 3 needle carb, all the better as you can richen the hover setting directly. If not, you're best to richen the high end needle first.
Once the hover setting is correct, set the high end needle in a very similar fashion to the hover setting. Fly the heli at full speed and somewhere between 100-200 feet altitude with head speed at 1500 -1900 RPM as appropriate for your heli and skill level. Generally, larger helis and lesser degrees of experience correlate with lower head speeds and vice versa. Hit the throttle hold and see if the motor again drops immediately to idle or does the run on, ring- ding thing. If it immediately drops to idle then lean the high end needle a couple of clicks and try again, if it doesn't immediately go to idle, then richen it 4 clicks and try again. You want it about 2-3 click on the rich side of wanting to run on.
All this presumes that the cooling system, fuel, tank, plug, plumbing, muffler, and motor are in good condition/ clean/properly connected, etc. It also presumes that the motor in question has no issues, that the cooling system on the heli is adequate, and that you're using an appropriate plug, muffler, and fuel. Unfortunately, these are some pretty big if's. There are a lot of unworkable combinations out there, but some absolutes that so far haven't failed me are: Hatori mufflers, Enya #3 plugs, and Cool Power 30% fuel always work. They are the most expensive of the options and many others will work, depending on the circumstances, but if you're really having problems, you can at least eliminate the muffler, plug, or fuel as the cause if you've got a Hatori in good condition, a new Enya #3, and a fresh jug of CP30.
I'm open to any suggestions or comments. My way is absolutely not the only way, and I know there are many others, but this has worked well for me to get in the ball park. It's taken a whole lot longer to type it out than to actually do it -Steve's theorem has been: you can set it in 5 minutes or you can't get it in 5 hours. I see lots of folks trying to tune out some basic problems that have nothing to do with the needles or trying to adjust the high end needle to get the low end mix right. If the motor doesn't run right after you've gone through the steps as above, you'll need to figure out why and no amount of needle tweaking is likely to get it right. Hope this helps. steve.
In order to get the motor started, you need to start with the manufacturers settings. Unfortunately, most don't give you any indication for how to adjust the low end needle, so what to do? First open the high end needle the recommended number of turns. Now set the idle throttle point so that the carb is open about 1mm, hook up some tubing to the fuel inlet and blow. Adjust the LOW (NOT high end, it's important you figure out from the start which is which) end needle so you can just barely blow through the tubing and you can hear air passing into the carb inlet. Now fill the tank and start the motor. Assuming it starts, then adjust the throttle ATV to give a slightly higher than normal idle. If it won't start, then open the throttle little by little until it's no more than 1/4 of the way open and keep trying. Make sure you have a good hold of the head as you do this so it doesn't take off and make hamburger out of your arm. Keep the radio on and be ready to turn the throttle down as you do this. If it still won't start, then your either too rich or too lean. By this point, if it's rich you've probably got some fuel spitting out the exhaust and you need to start leaning the low end needle 1/4 turn at a time until it does start. If it's too lean, then the exhaust will be dry, or very nearly so, and you need to start opening the low end needle 1/4 turn at a time. Once you get the thing running and the ATV set for a reasonable idle, you can further tune the low end needle by pinching the fuel line and if the motor speeds up somewhat for about 3-5 seconds before dying, you're about right. If the motor just dies straight away w/o speeding up, it's too lean, and needs to be richened up, if it speeds up a lot before dying, it's rich and needs leaning out. Next adjust the ATV for a nice slow idle.
Now it's time to fly. With the low end set and the high end at the recommended # of turns, it should hover OK. More than likely it will be a bit rich as the manufacturers tend to err on the rich side with their recommendations. If it's rich, just leave it alone at this point. If it's lean, it may run rough, but the #1 thing to look for is if it immediately drops into a nice low idle when you set it back down. Any running on, ring-dinging, or hesitation in going back to idle indicates the motor is running hot and the needles need to be adjusted richer accordingly. If you've got a 3 needle carb, all the better as you can richen the hover setting directly. If not, you're best to richen the high end needle first.
Once the hover setting is correct, set the high end needle in a very similar fashion to the hover setting. Fly the heli at full speed and somewhere between 100-200 feet altitude with head speed at 1500 -1900 RPM as appropriate for your heli and skill level. Generally, larger helis and lesser degrees of experience correlate with lower head speeds and vice versa. Hit the throttle hold and see if the motor again drops immediately to idle or does the run on, ring- ding thing. If it immediately drops to idle then lean the high end needle a couple of clicks and try again, if it doesn't immediately go to idle, then richen it 4 clicks and try again. You want it about 2-3 click on the rich side of wanting to run on.
All this presumes that the cooling system, fuel, tank, plug, plumbing, muffler, and motor are in good condition/ clean/properly connected, etc. It also presumes that the motor in question has no issues, that the cooling system on the heli is adequate, and that you're using an appropriate plug, muffler, and fuel. Unfortunately, these are some pretty big if's. There are a lot of unworkable combinations out there, but some absolutes that so far haven't failed me are: Hatori mufflers, Enya #3 plugs, and Cool Power 30% fuel always work. They are the most expensive of the options and many others will work, depending on the circumstances, but if you're really having problems, you can at least eliminate the muffler, plug, or fuel as the cause if you've got a Hatori in good condition, a new Enya #3, and a fresh jug of CP30.
I'm open to any suggestions or comments. My way is absolutely not the only way, and I know there are many others, but this has worked well for me to get in the ball park. It's taken a whole lot longer to type it out than to actually do it -Steve's theorem has been: you can set it in 5 minutes or you can't get it in 5 hours. I see lots of folks trying to tune out some basic problems that have nothing to do with the needles or trying to adjust the high end needle to get the low end mix right. If the motor doesn't run right after you've gone through the steps as above, you'll need to figure out why and no amount of needle tweaking is likely to get it right. Hope this helps. steve.