Needle Valve Question
10-27-2002 | 11:00 PM
#1
Thread Starter
Junior Member
My Feedback: (1)
Joined: Sep 2002
Posts: 14
Likes: 0
Received 0 Likes
on
0 Posts
From: Baltimore,
MD
Needle Valve Question
OK ... I don't quite have this needle valve down yet. I've been flying for a year, and have never had to adjust it until now.
On a day this is COOLER than it has been, one wants to RICHEN the mixture (counterclockwise turn) and on a HOTTER day, one wants to LEAN the mixture (clockwise turn) right?? or do I have this bass Ackwards?
TY
John
On a day this is COOLER than it has been, one wants to RICHEN the mixture (counterclockwise turn) and on a HOTTER day, one wants to LEAN the mixture (clockwise turn) right?? or do I have this bass Ackwards?
TY
John
10-28-2002 | 12:07 AM
#2
My Feedback: (13)
Joined: Jan 2002
Posts: 1,857
Likes: 0
Received 0 Likes
on
0 Posts
From: Chesterfield, MO
Yes, Generally cooler requires richer setting
Here is one theory: The cooler air contains more air molecules per cubic inch (the air is denser). So to keep the mixture about the same you need more fuel too. So you open up the needle valve in colder weather.
Really you need to be able to get this right regardless in any weather. One of my favorite techniques is if you can get access to the fuel line while the engine is running at full throttle, pinch it off either with your fingers or with a needle nose pliers. The engine should speed up somewhat before it dies. If it dies immediately it is too lean.
Another technique, even easier, is to hold the plane straight up and open the throttle to wide open. the engine should pull at least as strong in this position as it does when it was level. If it sags or quits it is too lean.
Really you need to be able to get this right regardless in any weather. One of my favorite techniques is if you can get access to the fuel line while the engine is running at full throttle, pinch it off either with your fingers or with a needle nose pliers. The engine should speed up somewhat before it dies. If it dies immediately it is too lean.
Another technique, even easier, is to hold the plane straight up and open the throttle to wide open. the engine should pull at least as strong in this position as it does when it was level. If it sags or quits it is too lean.
10-28-2002 | 12:18 AM
#3
Needle Valve
John;
2 Strokes basically are very simple to adjust the same basically regardless of temperature changes for sport engines.
Start your motor and let it run for about 30 sec to bring up the operating temp. (1 Minute if in Cold temps)
Adjust the high speed needle to an approx peak/lean position.
Now pinch the fuel line and listen to the engine, If you hear no change in RPM then you are to lean. Richen it up and do it again. pinching the fuel line for a second and listening for a discernible change in RPM. Once you hear the change then back it off 2-3 clicks and go fly.
With a Tach! you have an adjustment from 300-1000 Rpm for peak performance. As your new to the hobby bring your engine to peak and back the needle valve off 500-700 RPM or even the 1K. This isn't a race engine it's a sport engine make it last. I still have motors running from 1949. You can verify the RPM drop by pinching the fuel line as stated above. Running the engine a little rich is a heck of alot safer then leaning one out and burning it up.
Have Fun
2 Strokes basically are very simple to adjust the same basically regardless of temperature changes for sport engines.
Start your motor and let it run for about 30 sec to bring up the operating temp. (1 Minute if in Cold temps)
Adjust the high speed needle to an approx peak/lean position.
Now pinch the fuel line and listen to the engine, If you hear no change in RPM then you are to lean. Richen it up and do it again. pinching the fuel line for a second and listening for a discernible change in RPM. Once you hear the change then back it off 2-3 clicks and go fly.
With a Tach! you have an adjustment from 300-1000 Rpm for peak performance. As your new to the hobby bring your engine to peak and back the needle valve off 500-700 RPM or even the 1K. This isn't a race engine it's a sport engine make it last. I still have motors running from 1949. You can verify the RPM drop by pinching the fuel line as stated above. Running the engine a little rich is a heck of alot safer then leaning one out and burning it up.
Have Fun
