Zenoah 45 LSN has to be really rich. Is this normal?
05-19-2014, 05:47 AM
#1
Moderator
Thread Starter
Zenoah 45 LSN has to be really rich. Is this normal?
Engine is a Zenoah 45 with an RCexcel ignition and Walbro carb. No accelerator pump on the carb.
I'm about 3/4 of a turn on the LSN from peak on this engine to be able to get it to transition from idle to full throttle without dying. This is my first gasser, and none of my glow engines have to be that rich. Using the tach, I found that the idle mix went from 2700 to 1600 rpm at the same throttle setting going from peak to where it is now. I get a small hesitation still when I open the throttle from idle to full quickly. The HSN is set 300-400 rpm rich of peak.
I do have the throttle set up where the servo arm points directly backwards at the closed position and just a bit past 90 degrees at full throttle. That gives me the slowest/finest movement at the low end. I also slowed down the servo as much as I could without hurting the acceleration speed from mid to full throttle. But if I tune the LSN anywhere close to a peaked setting, I have to advance the throttle very slowly to keep the engine running up to about mid throttle, then it handles the acceleration fine. So is this pretty typical for gassers, or do I have a problem?
I'm about 3/4 of a turn on the LSN from peak on this engine to be able to get it to transition from idle to full throttle without dying. This is my first gasser, and none of my glow engines have to be that rich. Using the tach, I found that the idle mix went from 2700 to 1600 rpm at the same throttle setting going from peak to where it is now. I get a small hesitation still when I open the throttle from idle to full quickly. The HSN is set 300-400 rpm rich of peak.
I do have the throttle set up where the servo arm points directly backwards at the closed position and just a bit past 90 degrees at full throttle. That gives me the slowest/finest movement at the low end. I also slowed down the servo as much as I could without hurting the acceleration speed from mid to full throttle. But if I tune the LSN anywhere close to a peaked setting, I have to advance the throttle very slowly to keep the engine running up to about mid throttle, then it handles the acceleration fine. So is this pretty typical for gassers, or do I have a problem?
05-19-2014, 08:29 AM
#2
My Feedback: (19)
It is normal to set the LSN as lean as you can but still retain good transition when you advance the throttle.
300 - 400 RPM rich of peak on the HSN might be a bit rich for a gasser. Maybe 200 or so would be closer to normal. Many are quite happy at peak if you have good cooling airflow.
300 - 400 RPM rich of peak on the HSN might be a bit rich for a gasser. Maybe 200 or so would be closer to normal. Many are quite happy at peak if you have good cooling airflow.
05-19-2014, 09:40 AM
#3
Moderator
Thread Starter
Thanks. I'll lean the top end a little more. So I gather that it's normal to just get the LSN set to transition right without worrying about whether it's peaked on the idle?
05-19-2014, 01:22 PM
#5
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The idle should be set for transition and being reliable on landing and aborting a landing with a throttle up. I don't recommend any other considerations.
Your talking about "peak" gives me the impression that your thinking on the needle settings for gasser "reliablity" is not quite right.
I set idles at around 1900 rpm (for reliablity) if the model rolls consider some sort of friction provider on the axles.
I always use a flight idle of around 2100 for reliablity during spins and other engine out type flying.
The needle itself is always rich, on the low and high.
The high is the easiest, find the peak and richen it about 45 degrees (there should not be a RPM drop ( it is not a glow)).
The low speed needle is a little harder. The air opening is involved and how I set it is little different then average.
But when done the engine goes from 1900 to full without any stumbles or hesitation, none!
Your talking about "peak" gives me the impression that your thinking on the needle settings for gasser "reliablity" is not quite right.
I set idles at around 1900 rpm (for reliablity) if the model rolls consider some sort of friction provider on the axles.
I always use a flight idle of around 2100 for reliablity during spins and other engine out type flying.
The needle itself is always rich, on the low and high.
The high is the easiest, find the peak and richen it about 45 degrees (there should not be a RPM drop ( it is not a glow)).
The low speed needle is a little harder. The air opening is involved and how I set it is little different then average.
But when done the engine goes from 1900 to full without any stumbles or hesitation, none!
05-20-2014, 10:41 AM
#6
Moderator
Thread Starter
Yep, this is my first gas engine kmeyers, so it's entirely possible I'm approaching it the wrong way. With glow engines, I set the high speed a bit rich and then peak the low end, then richen until it transitions right. It's not usually more than 1/8 turn or so to do that, so I'm just not used to having to go over 1/2 a turn and so many RPM richer to make the engine accelerate.
