50 CC missing in midrange
12-20-2008, 08:12 AM
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50 CC missing in midrange
I have a CCRC 50 that has been running great. It has about 1 hr run time on it. It starts easily and has good power.
Idle is almost a tickover and can almost see the prop. The issue is that in the mid range for power back flying there is infrequent bark in the exhaust. Doesn't affect reliability and I am sure this is a fuel mixture as the engine is breaking in. But this begs the question? High speed or Low speed needle? I don't want to get too far off of where it is now as it has vertical power for a 16.5# bird and great reliable idle. Just annoying the bark in the exhaust that should not be there.
Oil/fuel. Full synthetic 2 stroke racing oil 2 oz conventional 2 stroke oil 1 1/4 oz to 1 gal of gas.
Any thoughts. Really hard to get to the needles with the cowl on so the adjustment must be made cowl off and then tested.
I considered the static pressure on the diaphram but this bark will occur in straight level power reduced flight. During maneuvers the power pulls strong with no bark. This is why I am guessing it is just a tad bit rich in mid range and wondering which needle to adjust. Thank in advance.
Idle is almost a tickover and can almost see the prop. The issue is that in the mid range for power back flying there is infrequent bark in the exhaust. Doesn't affect reliability and I am sure this is a fuel mixture as the engine is breaking in. But this begs the question? High speed or Low speed needle? I don't want to get too far off of where it is now as it has vertical power for a 16.5# bird and great reliable idle. Just annoying the bark in the exhaust that should not be there.
Oil/fuel. Full synthetic 2 stroke racing oil 2 oz conventional 2 stroke oil 1 1/4 oz to 1 gal of gas.
Any thoughts. Really hard to get to the needles with the cowl on so the adjustment must be made cowl off and then tested.
I considered the static pressure on the diaphram but this bark will occur in straight level power reduced flight. During maneuvers the power pulls strong with no bark. This is why I am guessing it is just a tad bit rich in mid range and wondering which needle to adjust. Thank in advance.
12-20-2008, 10:28 AM
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RE: 50 CC missing in midrange
pull the spark plug right after you get finishing shutting the motor down and see if its brownish or grey. sounds like its going to be grey. when you hold full throttle on the ground does it climb slowely in RPM on the last few hunderd or does it get there and drop just a little from peak?
12-20-2008, 10:32 AM
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RE: 50 CC missing in midrange
I will check to see if it drops,, but from what I remember from flying yesterday it did not drop at full throttle at accleration. It stayed solid. I always allow a 30 second full throttle run prior to take off when the engine is cold.
When flying however it does pull stronger going vertical and runs smoother in a climb. Only level cruising at about 1/2 throttle does is seem to bark a bit.
When flying however it does pull stronger going vertical and runs smoother in a climb. Only level cruising at about 1/2 throttle does is seem to bark a bit.
12-20-2008, 12:43 PM
#4
RE: 50 CC missing in midrange
I think the low speed needle is too rich.
"It starts easily" most engines with a properly tuned low speed needle will be a little more work to start.
Do the following with a warmed up engine:
Run it up to full throttle and hold it for 10 full seconds.
Drop throttle to 1/2 throttle. If it's still running clean, start dropping throttle 1 click at a time. You can feel each click on your TX. Drop it down 1 click and wait 10 seconds. If it runs clean, drop another click.
You will reach a point where it will start to miss or burble. Shut it down and lean the low speed needle a TINY bit.
Start over. Run to full throttle for 10 seconds. Drop it down to 1/2 throttle. Now back it down 1 click at a time. Wait 10 seconds. As long as it runs clean, continue to drop 1 click every 10 seconds.
Each time, you will be able to drop farther and farther from 1/2 throttle before it starts to burble.
Stop the engine and lean the low speed needle when it burbles. When I say to lean it, I'm talking about 1/2 the thickness of the slot in the mixture screw. We're talking about a blonde *!@^% hair. Just a TINY bit.
Eventually, you will be able to run it all the way up to wide open and hold it for 10 seconds. Drop to 1/2 throttle and then back it down 1 click every 10 seconds until you are at idle speed. If it runs clean all the way from 1/2 throttle to idle, you're done. Adjust the endpoint on your throttle servo because as you lean the low speed needle the engine will pick up speed. Adjust the endpoint until it idles where you want it.
ALWAYS go back and check your high speed needle after making adjustments to the low speed. If you leaned the low speed more than about 1/8 turn, I guarantee it effected the high speed (leaned it). Run the high speed in until it peaks RPM. Back it up rich about 200RPM. Go fly it.
It sounds to me like you're running 100:1 oil. 1 1/4oz of oil in a gallon of fuel? Or was that 2oz of oil?
I'm sure somebody will come on here and say I'm an idiot and you'll burn your engine to a crisp if you follow my advice and run it wide open on the ground for that long.
This is how I tune all my gassers and I use 40:1 mix. I've NEVER cooked an engine. The guy who taught me this method of tuning (Tony from Pueblo,CO. flying field) isn't burning up his engines either. I've read others mention this same tuning technique on these forums. If it cooked your engine, you didn't have it baffled right or you weren't running enough oil......... or BOTH.
"It starts easily" most engines with a properly tuned low speed needle will be a little more work to start.
Do the following with a warmed up engine:
Run it up to full throttle and hold it for 10 full seconds.
Drop throttle to 1/2 throttle. If it's still running clean, start dropping throttle 1 click at a time. You can feel each click on your TX. Drop it down 1 click and wait 10 seconds. If it runs clean, drop another click.
You will reach a point where it will start to miss or burble. Shut it down and lean the low speed needle a TINY bit.
Start over. Run to full throttle for 10 seconds. Drop it down to 1/2 throttle. Now back it down 1 click at a time. Wait 10 seconds. As long as it runs clean, continue to drop 1 click every 10 seconds.
Each time, you will be able to drop farther and farther from 1/2 throttle before it starts to burble.
Stop the engine and lean the low speed needle when it burbles. When I say to lean it, I'm talking about 1/2 the thickness of the slot in the mixture screw. We're talking about a blonde *!@^% hair. Just a TINY bit.
Eventually, you will be able to run it all the way up to wide open and hold it for 10 seconds. Drop to 1/2 throttle and then back it down 1 click every 10 seconds until you are at idle speed. If it runs clean all the way from 1/2 throttle to idle, you're done. Adjust the endpoint on your throttle servo because as you lean the low speed needle the engine will pick up speed. Adjust the endpoint until it idles where you want it.
ALWAYS go back and check your high speed needle after making adjustments to the low speed. If you leaned the low speed more than about 1/8 turn, I guarantee it effected the high speed (leaned it). Run the high speed in until it peaks RPM. Back it up rich about 200RPM. Go fly it.
It sounds to me like you're running 100:1 oil. 1 1/4oz of oil in a gallon of fuel? Or was that 2oz of oil?
I'm sure somebody will come on here and say I'm an idiot and you'll burn your engine to a crisp if you follow my advice and run it wide open on the ground for that long.
This is how I tune all my gassers and I use 40:1 mix. I've NEVER cooked an engine. The guy who taught me this method of tuning (Tony from Pueblo,CO. flying field) isn't burning up his engines either. I've read others mention this same tuning technique on these forums. If it cooked your engine, you didn't have it baffled right or you weren't running enough oil......... or BOTH.
12-20-2008, 01:44 PM
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RE: 50 CC missing in midrange
ORIGINAL: Rcpilot
I think the low speed needle is too rich.
"It starts easily" most engines with a properly tuned low speed needle will be a little more work to start.
Do the following with a warmed up engine:
Run it up to full throttle and hold it for 10 full seconds.
Drop throttle to 1/2 throttle. If it's still running clean, start dropping throttle 1 click at a time. You can feel each click on your TX. Drop it down 1 click and wait 10 seconds. If it runs clean, drop another click.
You will reach a point where it will start to miss or burble. Shut it down and lean the low speed needle a TINY bit.
Start over. Run to full throttle for 10 seconds. Drop it down to 1/2 throttle. Now back it down 1 click at a time. Wait 10 seconds. As long as it runs clean, continue to drop 1 click every 10 seconds.
Each time, you will be able to drop farther and farther from 1/2 throttle before it starts to burble.
Stop the engine and lean the low speed needle when it burbles. When I say to lean it, I'm talking about 1/2 the thickness of the slot in the mixture screw. We're talking about a blonde *!@^% hair. Just a TINY bit.
Eventually, you will be able to run it all the way up to wide open and hold it for 10 seconds. Drop to 1/2 throttle and then back it down 1 click every 10 seconds until you are at idle speed. If it runs clean all the way from 1/2 throttle to idle, you're done. Adjust the endpoint on your throttle servo because as you lean the low speed needle the engine will pick up speed. Adjust the endpoint until it idles where you want it.
ALWAYS go back and check your high speed needle after making adjustments to the low speed. If you leaned the low speed more than about 1/8 turn, I guarantee it effected the high speed (leaned it). Run the high speed in until it peaks RPM. Back it up rich about 200RPM. Go fly it.
It sounds to me like you're running 100:1 oil. 1 1/4oz of oil in a gallon of fuel? Or was that 2oz of oil?
I'm sure somebody will come on here and say I'm an idiot and you'll burn your engine to a crisp if you follow my advice and run it wide on on the ground for that long. This is how I tune all my gassers and I use 40:1 mix. I've NEVER cooked an engine. The guy who taught me this method of tuning (Tony from Pueblo,CO. flying field) isn't burning up his engines either. I've read others mention this same tuning technique on these forums. If it cooked your engine, you didn't have it baffled right or you weren't running enough oil......... or BOTH.
I think the low speed needle is too rich.
"It starts easily" most engines with a properly tuned low speed needle will be a little more work to start.
Do the following with a warmed up engine:
Run it up to full throttle and hold it for 10 full seconds.
Drop throttle to 1/2 throttle. If it's still running clean, start dropping throttle 1 click at a time. You can feel each click on your TX. Drop it down 1 click and wait 10 seconds. If it runs clean, drop another click.
You will reach a point where it will start to miss or burble. Shut it down and lean the low speed needle a TINY bit.
Start over. Run to full throttle for 10 seconds. Drop it down to 1/2 throttle. Now back it down 1 click at a time. Wait 10 seconds. As long as it runs clean, continue to drop 1 click every 10 seconds.
Each time, you will be able to drop farther and farther from 1/2 throttle before it starts to burble.
Stop the engine and lean the low speed needle when it burbles. When I say to lean it, I'm talking about 1/2 the thickness of the slot in the mixture screw. We're talking about a blonde *!@^% hair. Just a TINY bit.
Eventually, you will be able to run it all the way up to wide open and hold it for 10 seconds. Drop to 1/2 throttle and then back it down 1 click every 10 seconds until you are at idle speed. If it runs clean all the way from 1/2 throttle to idle, you're done. Adjust the endpoint on your throttle servo because as you lean the low speed needle the engine will pick up speed. Adjust the endpoint until it idles where you want it.
ALWAYS go back and check your high speed needle after making adjustments to the low speed. If you leaned the low speed more than about 1/8 turn, I guarantee it effected the high speed (leaned it). Run the high speed in until it peaks RPM. Back it up rich about 200RPM. Go fly it.
It sounds to me like you're running 100:1 oil. 1 1/4oz of oil in a gallon of fuel? Or was that 2oz of oil?
I'm sure somebody will come on here and say I'm an idiot and you'll burn your engine to a crisp if you follow my advice and run it wide on on the ground for that long.
This is how I tune all my gassers and I use 40:1 mix. I've NEVER cooked an engine. The guy who taught me this method of tuning (Tony from Pueblo,CO. flying field) isn't burning up his engines either. I've read others mention this same tuning technique on these forums. If it cooked your engine, you didn't have it baffled right or you weren't running enough oil......... or BOTH.
Actually the oil was 2 1/4 oz of synt oil AND 1 oz of regular oil. This was blended with about 3 1/2 qts of gas to make the ratio close to 32:1 so no real risk of burning out the engine. The oil I am using was used in my son's dirt bike at 100 cc in a 100:1 ratio at full throttle on the dirt track with no issues. So here at 32:1 and some conventional 2 stroke oil I don't think it will have an oil issue. But really good reco on tuning carb. I copied/pasted and will do it on next start up after Christmas. I did leave it a bit rich due to the engine just barely has 2 hrs of run time.
12-20-2008, 02:39 PM
#6
RE: 50 CC missing in midrange
Okay, with that oil mix, you should have no problems. I always cringe when I see people mixing 100:1, but to each his own. Your mix at 32:1 sounds fine to me.
Try the tuning method. It usually works. Takes about 30 or 45 minutes to get it all dialed in. The constant starting and stopping gets old, but once you're finished tuning it, forget about it. Fly it.
You will notice your starting becomes a bit more work with the bottom end leaner. Usually a nice wet choke helps. If it bothers you, richen the low speed needle a tiny bit and deal with a burble at low throttle settings. That should clear out your mid range burble and then it would only burble at very low throttle positions.
Try the tuning method. It usually works. Takes about 30 or 45 minutes to get it all dialed in. The constant starting and stopping gets old, but once you're finished tuning it, forget about it. Fly it.
You will notice your starting becomes a bit more work with the bottom end leaner. Usually a nice wet choke helps. If it bothers you, richen the low speed needle a tiny bit and deal with a burble at low throttle settings. That should clear out your mid range burble and then it would only burble at very low throttle positions.
12-21-2008, 09:20 AM
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RE: 50 CC missing in midrange
Hi Jimcork,
I have been using a dl-50 for about 2 gallons of fuel, initially there was no problem, now i have been getting a vicious increase and decrease in r.p.m at about 40% throttle and it continues throughout unless i increase the throttle to higher than 40% or go below to idle speed. My friends at the field have tried to solve it by turning both the high and low needels to godknows what settings, now i have an engine which works well on idle and any thing above 60% throttle. further from idle to 40% power the engine is very consistent and also i get full power at 60% of the throttle stick movenment.Please can u help me set it right. any suggesstions are welcome
Thanks,
Shivan.
I have been using a dl-50 for about 2 gallons of fuel, initially there was no problem, now i have been getting a vicious increase and decrease in r.p.m at about 40% throttle and it continues throughout unless i increase the throttle to higher than 40% or go below to idle speed. My friends at the field have tried to solve it by turning both the high and low needels to godknows what settings, now i have an engine which works well on idle and any thing above 60% throttle. further from idle to 40% power the engine is very consistent and also i get full power at 60% of the throttle stick movenment.Please can u help me set it right. any suggesstions are welcome
Thanks,
Shivan.
12-21-2008, 09:29 AM
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RE: 50 CC missing in midrange
ORIGINAL: shivan
Hi Jimcork,
I have been using a dl-50 for about 2 gallons of fuel, initially there was no problem, now i have been getting a vicious increase and decrease in r.p.m at about 40% throttle and it continues throughout unless i increase the throttle to higher than 40% or go below to idle speed. My friends at the field have tried to solve it by turning both the high and low needels to godknows what settings, now i have an engine which works well on idle and any thing above 60% throttle. further from idle to 40% power the engine is very consistent and also i get full power at 60% of the throttle stick movenment.Please can u help me set it right. any suggesstions are welcome
Thanks,
Shivan.
Hi Jimcork,
I have been using a dl-50 for about 2 gallons of fuel, initially there was no problem, now i have been getting a vicious increase and decrease in r.p.m at about 40% throttle and it continues throughout unless i increase the throttle to higher than 40% or go below to idle speed. My friends at the field have tried to solve it by turning both the high and low needels to godknows what settings, now i have an engine which works well on idle and any thing above 60% throttle. further from idle to 40% power the engine is very consistent and also i get full power at 60% of the throttle stick movenment.Please can u help me set it right. any suggesstions are welcome
Thanks,
Shivan.
1) Look for air leaks anywhere from the clunk to the tank. You might have a delivery problem.
2) Check the plug gap make sure the gap is correct. I use .024 " you can convert to MM if you like. You might just try a new plug
3) I don't expect a problem with the ignition module or it's power supply
4) My best shot here is you have a bad diaphram in the carb. or trash in the needle circuit for fuel delivery. If you can get a rebuild kit for the carb you might try to replace the diaphrams and check valves.
Hope this helps.
