NGH 30cc 4 stroke
10-13-2020, 09:16 AM
#76
Yes, my TDC mark is also on the top.
Remove the spark plug, and make sure the piston is exactly at the top when you look at the timing dot, as you can easily rock it back and fourth over the TDC, and the timing dot will look out of alignment.
I have been bench running mine recently with the carb gasket mod.
It could be that beacuse the crank pressure is so hard, its pushing air past the seals inside carb, and causing bubbles
Try make a new thicker carb gasket, and cut a path in it so it will get both pressure from the crank case, and from the intake at the same time.
You can see in my video in the pressure line that oil is actually moving up, and being injested into the carb....which clears the line, and the pressure is not too high.
Remove the spark plug, and make sure the piston is exactly at the top when you look at the timing dot, as you can easily rock it back and fourth over the TDC, and the timing dot will look out of alignment.
I have been bench running mine recently with the carb gasket mod.
It could be that beacuse the crank pressure is so hard, its pushing air past the seals inside carb, and causing bubbles
Try make a new thicker carb gasket, and cut a path in it so it will get both pressure from the crank case, and from the intake at the same time.
You can see in my video in the pressure line that oil is actually moving up, and being injested into the carb....which clears the line, and the pressure is not too high.
10-13-2020, 09:22 AM
#77
pic of a modded gasket so it can get pump pressure from the intake, and still from the crank case.
Try it, it wont break anything, and its an easy mod to try. If not satisfied, just re-install the original gasket again :-)
https://www.flyinggiants.com/forums/...=195521&page=4
Try it, it wont break anything, and its an easy mod to try. If not satisfied, just re-install the original gasket again :-)
https://www.flyinggiants.com/forums/...=195521&page=4
Last edited by SJN; 10-13-2020 at 09:25 AM.
10-13-2020, 01:13 PM
#78
Ok so here is before valve adjustment. Lots of bubble coming out of the carb
idle
run up
here I gaped the valves to .08mm as per the instructions with the piston at TDC and the punch on the cam all the way down.
here is video of after setting the valves.
there is not nearly as much sputtering as before but there are still bubbles in the fuel line.
again my needles are set at 1 5/8H and 1 3/8L. I'm breaking in with 20:1 91 octane rev fuel (no ethanol) and redline oil.
so you think it's a gasket issue? I put on a new carburetor.I changed the spark plug to an NGH CM6.
from idle to full if I punch it, it dies. I have to slow transition from idle to full. Does this mean I'm too lean on the high needle?
I guess what I'm asking is should I begin tuning or is there still something I need to fix.
thanks
-Matt
idle
run up
here I gaped the valves to .08mm as per the instructions with the piston at TDC and the punch on the cam all the way down.
here is video of after setting the valves.
there is not nearly as much sputtering as before but there are still bubbles in the fuel line.
again my needles are set at 1 5/8H and 1 3/8L. I'm breaking in with 20:1 91 octane rev fuel (no ethanol) and redline oil.
so you think it's a gasket issue? I put on a new carburetor.I changed the spark plug to an NGH CM6.
from idle to full if I punch it, it dies. I have to slow transition from idle to full. Does this mean I'm too lean on the high needle?
I guess what I'm asking is should I begin tuning or is there still something I need to fix.
thanks
-Matt
10-13-2020, 01:38 PM
#79
Yes, you need to tune it for the best possible running. And you need a tach to see the rpm.....you cant hear the difference like on a nitro engine.
Give it full throttle, and try lean the high speed needle, and see if the RPM rises, or falls If it rises, lean it a bit more...and keep on doing so until it peaks, then back off a little. If rpm drops when you lean it, then just start richening it in stead until it peaks. On this engine, you want the low end needle as lean as possible. It will make the engine run much smoother. So keep on leaning it a little, and blip the throttle, and check that the engine accelerates fast.....keep on leaning it.......until you can feel it begins to take longer to accelerate......then richen it a bit again so the transition is fast.. Because the low needle also effects the high needle, and you probably just leaned the low speed, this has also lean the high speed needle now.. So give it full throttle, and richen it a little, until you get peak speed again...and then back off a little. That should be it. Also, dont run the engine in the plane without the wings on....it will tear up your fuselage from torque and vibration in no time....put the wings on to dampen the vibration.
Give it full throttle, and try lean the high speed needle, and see if the RPM rises, or falls If it rises, lean it a bit more...and keep on doing so until it peaks, then back off a little. If rpm drops when you lean it, then just start richening it in stead until it peaks. On this engine, you want the low end needle as lean as possible. It will make the engine run much smoother. So keep on leaning it a little, and blip the throttle, and check that the engine accelerates fast.....keep on leaning it.......until you can feel it begins to take longer to accelerate......then richen it a bit again so the transition is fast.. Because the low needle also effects the high needle, and you probably just leaned the low speed, this has also lean the high speed needle now.. So give it full throttle, and richen it a little, until you get peak speed again...and then back off a little. That should be it. Also, dont run the engine in the plane without the wings on....it will tear up your fuselage from torque and vibration in no time....put the wings on to dampen the vibration.
10-13-2020, 02:11 PM
#80
Yes, you need to tune it for the best possible running. And you need a tach to see the rpm.....you cant hear the difference like on a nitro engine.
Give it full throttle, and try lean the high speed needle, and see if the RPM rises, or falls If it rises, lean it a bit more...and keep on doing so until it peaks, then back off a little. If rpm drops when you lean it, then just start richening it in stead until it peaks. On this engine, you want the low end needle as lean as possible. It will make the engine run much smoother. So keep on leaning it a little, and blip the throttle, and check that the engine accelerates fast.....keep on leaning it.......until you can feel it begins to take longer to accelerate......then richen it a bit again so the transition is fast.. Because the low needle also effects the high needle, and you probably just leaned the low speed, this has also lean the high speed needle now.. So give it full throttle, and richen it a little, until you get peak speed again...and then back off a little. That should be it. Also, dont run the engine in the plane without the wings on....it will tear up your fuselage from torque and vibration in no time....put the wings on to dampen the vibration.
Give it full throttle, and try lean the high speed needle, and see if the RPM rises, or falls If it rises, lean it a bit more...and keep on doing so until it peaks, then back off a little. If rpm drops when you lean it, then just start richening it in stead until it peaks. On this engine, you want the low end needle as lean as possible. It will make the engine run much smoother. So keep on leaning it a little, and blip the throttle, and check that the engine accelerates fast.....keep on leaning it.......until you can feel it begins to take longer to accelerate......then richen it a bit again so the transition is fast.. Because the low needle also effects the high needle, and you probably just leaned the low speed, this has also lean the high speed needle now.. So give it full throttle, and richen it a little, until you get peak speed again...and then back off a little. That should be it. Also, dont run the engine in the plane without the wings on....it will tear up your fuselage from torque and vibration in no time....put the wings on to dampen the vibration.
I'll start to tune it with the tach. then and see how it goes. I see from your video that you have a bubble in your fuel line as well.
im optimistic I'm getting in the ball park because I was able to get full throttle without sputtering or dying.
idle is much better but I'll lean out the low
thank you
-Matt
04-22-2021, 05:34 AM
#81
Yes, you need to tune it for the best possible running. And you need a tach to see the rpm.....you cant hear the difference like on a nitro engine.
Give it full throttle, and try lean the high speed needle, and see if the RPM rises, or falls If it rises, lean it a bit more...and keep on doing so until it peaks, then back off a little. If rpm drops when you lean it, then just start richening it in stead until it peaks. On this engine, you want the low end needle as lean as possible. It will make the engine run much smoother. So keep on leaning it a little, and blip the throttle, and check that the engine accelerates fast.....keep on leaning it.......until you can feel it begins to take longer to accelerate......then richen it a bit again so the transition is fast.. Because the low needle also effects the high needle, and you probably just leaned the low speed, this has also lean the high speed needle now.. So give it full throttle, and richen it a little, until you get peak speed again...and then back off a little. That should be it. Also, dont run the engine in the plane without the wings on....it will tear up your fuselage from torque and vibration in no time....put the wings on to dampen the vibration.
Give it full throttle, and try lean the high speed needle, and see if the RPM rises, or falls If it rises, lean it a bit more...and keep on doing so until it peaks, then back off a little. If rpm drops when you lean it, then just start richening it in stead until it peaks. On this engine, you want the low end needle as lean as possible. It will make the engine run much smoother. So keep on leaning it a little, and blip the throttle, and check that the engine accelerates fast.....keep on leaning it.......until you can feel it begins to take longer to accelerate......then richen it a bit again so the transition is fast.. Because the low needle also effects the high needle, and you probably just leaned the low speed, this has also lean the high speed needle now.. So give it full throttle, and richen it a little, until you get peak speed again...and then back off a little. That should be it. Also, dont run the engine in the plane without the wings on....it will tear up your fuselage from torque and vibration in no time....put the wings on to dampen the vibration.
the idle is very high right now. Any lower and she dies on time. I assume this is the low end being too rich? I tried to lean it but then it became erratic so I went back to the richer setting.
two good fun flights with no dead stick landings, though the engine did quit on rollout both times. I wish the idle would be a bit lower as my landings were pretty fast. I bounced one pretty bad a few times and Rex's head snapped off. Just way too fast and the big wing does not want to quit flying.
my muffler came loose and when I tried to tighten it, I stripped the threads. I ran it without the muffler and it was not too much louder. I ordered a new one as our club requires us to use a muffler.
thanks for your help!
-Matt
04-22-2021, 05:40 AM
#82
I have the same issues with my 4* with the DLE 20. Give the motor time to break in and eventually you will get that idle down. If you can mix spoilerons or flaperons, that can help land it. I used flaperons since I can get the idle down enough, helps to slow the plane down, spoilerons will help dump lift.
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Flyboywbl (04-22-2021)
05-11-2021, 07:35 AM
#83
I realized my sputtering issue was being way too rich on the high end. I leaned it out until it started to stutter and then I richened it about a 1/4 turn. Now she starts by hand much easier.
on the low and idle, I got it so it takes a good 10 seconds to load up and bog down but still has good throttle response. It runs great now!!
im thinking of switching to a three blade prop for some more drag to slow down. Right now it's swinging a 16x8 and she is a rocket. I almost want to try an 18x6 but im worried about prop clearance (hence the three blade idea). I also need to mix some flaperons in.
all in all, a great engine for the money
on the low and idle, I got it so it takes a good 10 seconds to load up and bog down but still has good throttle response. It runs great now!!
im thinking of switching to a three blade prop for some more drag to slow down. Right now it's swinging a 16x8 and she is a rocket. I almost want to try an 18x6 but im worried about prop clearance (hence the three blade idea). I also need to mix some flaperons in.
all in all, a great engine for the money
02-17-2022, 08:45 AM
#84
Join Date: Sep 2007
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Spark plug gap
I've found these motors to be somewhat sensitive to the spark plug gap. The plug as furnished with the engine was at .018, and the engine ran very hard, sounded terrible and wasn't very responsive to the needles. I tried different gap settings and settled on .024 which is a bit higher than normal for the CM-6 plug, but the engine responded very well to the change. Night and day difference. I now use this gap setting on all my NGH 4 stroke motors.
02-26-2022, 10:05 AM
#85
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The intake design of these motors are awful , they are all updraft instead of down draft so if it's mounted upside down thats perfect but if it's mounted upright it sucks and they have some seriously sharp bends to get into the combustion chamber.
02-26-2022, 10:45 AM
#86
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I've found these motors to be somewhat sensitive to the spark plug gap. The plug as furnished with the engine was at .018, and the engine ran very hard, sounded terrible and wasn't very responsive to the needles. I tried different gap settings and settled on .024 which is a bit higher than normal for the CM-6 plug, but the engine responded very well to the change. Night and day difference. I now use this gap setting on all my NGH 4 stroke motors.
Thanks for the info. I will try this on the Saito glow I'm converting to gas.
Tweaker
