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Steve Pierce
04-17-2018, 05:52 PM
Anybody had an issue with light Speed ignition cutting out. I have a carbon Cub here that keeps cutting on and off. Really gets your attention. Does it on left, right, both, emergency, with the key switch disconnected. Have checked all connections, read the book twice. called Klaus but he is in Germany and I think I irritated him. I don't want to start tearing things apart but hen you get up to pattern altitude and the engine starts missing like you are turning the key on and off it gets your blood pumping. Cub Crafters has never heard of this scenario either so i am hoping someone here might have some knowledge. I am out of ideas.

Bill Watson
04-17-2018, 06:22 PM
I had a very minor miss in flight, leaned the engine and determined which cylinder head temp would not come up then traced plug wire to proper coil and found a small spade connector loose, crimped it and solved the problem. Again it was minor.

Pete D
04-17-2018, 06:29 PM
Did this problem turn up after recent work? Confirm clearance between plug wires and sensor wires. Also check clearance of pickups to flywheel. Manual has a spec for that.

Steve Pierce
04-17-2018, 06:41 PM
Starter was changed about 2 flight hours prior. Spade terminals are tight. Have about .040" clearance on both crank sensors, manual calls for .030- .060". Have at least a 1/2" clearance on the between the sensor wires and anything else and quite a bit more than that between them and the plug wires. Appreciate the feedback, I'm still looking and reading.

N86250
04-17-2018, 10:44 PM
Water in the fuel?

wireweinie
04-18-2018, 12:10 AM
IF it's an electrical issue, check the common points. Grounds, breaker, switches, etc. Maybe hook an LED to the power terminal of each and run it up. If the LED flickers, you have intermittent power.
Dumb question but as N86250 brought up, are you sure it's an electrical issue?

Web

Steve Pierce
04-18-2018, 06:37 AM
Tanks sumped, gascolator drained and checked along with carburetor bowl with no water found. I have run tanks dry and switched to good tank and this feels like you turned the ignition switch on and off. It isn't like one plug is not firing it is like you are turning the engine on and off.

Farmboy
04-18-2018, 07:32 AM
Blocked fuel flow? Although it sounds more electrical related. Any chance of corroded terminals supplying grounds to the light speed itself? Whole system is losing connection?


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tempdoug
04-18-2018, 07:38 AM
Did the check engine light come on?:evil:

C130jake
04-18-2018, 07:52 AM
Klouse is German...donít take it personally. He seemed really irritated with me when I had some issues on my first engine start. CC and the guys in Kamloops were stumped. Klouse listened on the phone and told me it was an induction leak. It was.

I am sure you checked the ignition switch. Any chance of wire chafing thru the firewall?


Jake


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spinner2
04-18-2018, 07:56 AM
Assuming this is the O-340 Steve, how many hours on it? It is recommended to change out the leads between the coils and plugs after 500 hours. Otherwise the misses get worse and worse. I went 700 hours on mine before changing and won’t do that again. I thought I had big problems with the Lightspeed boxes but this was a simple fix. Leads are about $20 each.

I also had the scat leading into the air box get a loose flap on it that partially closed off the air flow and caused a cough, like carb ice.

A dead spot in the key switch shuts it down if you do an ariel L/R check. That gets your attention too.

wireweinie
04-18-2018, 11:25 AM
I'm assuming it is the dual set up? If so, it will be a common point for both sets. That's why I'm thinking breaker/switch/grounds. After looking at the diagrams, I'd open all backshells on the d-sub connectors and check for broken or chaffed wires. Also check closely for any stray strands of wire at one socket, touching an adjacent socket.

Web

Steve Pierce
04-18-2018, 05:32 PM
Checked the trigger wires and moved them a little. Checked the entire set of wires and found no abnormalities. Took the d-sub connectors off the two ignition boxes and then opened the connectors and everything looked fine. Key switch is disconnected from the system and using the circuit breakers to isolate the systems. Ran it with the tail tied to my truck and made a video that will take a while to upload but it should give you a better idea of what it is doing.

Gordon Misch
04-18-2018, 06:15 PM
A shot in the dark, knowing nothing about these systems - - Is it possible that the two units communicate with each other in any way, such that one could share a fault with the other?

Steve Pierce
04-18-2018, 06:18 PM
Supposed to be completely independent. I am starting to think I have something else wrong.

Gordon Misch
04-18-2018, 06:26 PM
Could you possibly hang an electric fence tester on a plug wire to observe if the spark continues when the engine cuts out?

Or maybe remove the lead from one plug, attach it to a spare plug that's in free air but grounded and watch the spark?

Check correct fuel flow to the carb?

flynlow
04-18-2018, 10:26 PM
Did you pull the finger screen/strainer on the carb?

Steve Pierce
04-19-2018, 06:41 AM
I did about 10 hours ago when I did the condition inspection. Gascolator screen was clean both then and now. Drained the carburetor again last night before I came home. All cylinders were 76-78/80 except one which was 70/80. Loaned the owner a set of compression gauges and my hose for automotive spark plugs but haven't gotten them back yet but pulling it through I can tell I have a soft cylinder and hear it through the carburetor.

Steve Pierce
04-19-2018, 07:11 AM
Here is the video I took of my engine run with the airplane tied to my truck. I went through the left, right, both and emergency ignition system with no change in how the engine was running. Sorry it is so shaky, that left window really flexes.

https://youtu.be/iOgBiLxUVzU

RaisedByWolves
04-19-2018, 07:31 AM
Whatís Jon at cubcrafters have to say?


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skywagon8a
04-19-2018, 07:32 AM
Steve,
Judging by the audio and tach indications in your video it doesn't appear to be rpm related which is making me think that it is not ignition. Not being familiar with that model airplane, spinner's suggestion sounds plausible. Can you completely remove any intake tube and retest?

I also had the scat leading into the air box get a loose flap on it that partially closed off the air flow and caused a cough, like carb ice.

Steve Pierce
04-19-2018, 07:37 AM
What’s Jon at cubcrafters have to say?


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Jon though fuel or induction leak Friday before last. Has the hoses and they are all tight. Gonna run fuel through the carburetor and try again.

Steve Pierce
04-19-2018, 07:38 AM
Steve,
Judging by the audio and tach indications in your video it doesn't appear to be rpm related which is making me think that it is not ignition. Not being familiar with that model airplane, spinner's suggestion sounds plausible. Can you completely remove any intake tube and retest?

I am not varying the throttle, put it 2200 rpm or so and left it.

Steve Pierce
04-19-2018, 07:42 AM
Steve,
Judging by the audio and tach indications in your video it doesn't appear to be rpm related which is making me think that it is not ignition. Not being familiar with that model airplane, spinner's suggestion sounds plausible. Can you completely remove any intake tube and retest?

Also, I was switching between the two ignition systems in that video and there was no change what so ever. I think if it had a bad ignition lead it would change depending on which ignition system, coil, plug wire and spark plug I was firing.

The system has two ignition boxes run from two separate buses running 2 separate coils each and an emergency battery that can isolate everything on the right side ignition system. The only common thing was the conventional L-R-Both-Start switch which I removed from the system.

Bill Watson
04-19-2018, 08:06 AM
I wonder if priming while it is missing would change the RPM? Maybe give a clue to fuel or air problem.

flynlow
04-19-2018, 08:11 AM
I have had this happen with high time irrigation engines. They build up carbon and it gets hot and fires off mixture before compression stroke. We would water inject them but I wouldn't advise that.
You may have a cracked piston from detonation or broken rings but that would be a result and not likely a cause.

skywagon8a
04-19-2018, 08:12 AM
It does sound a lot like an intermittent air intake blockage. Check that it is not sucking in some of the induction hose.

flynlow
04-19-2018, 08:14 AM
Dang, I deleted my thought on sluggish or sticking intake valve. It sounds like a intake backfire to me. Maybe a valve not getting completely closed before ignition on compression stroke.

spinner2
04-19-2018, 08:17 AM
There is a SB on the induction hoses if it has the glue-on style. Easy to tell if they’ve been changed. The new style looks like the Lycomings with hose clamps on each end.

The old style developed leaks.

Steve Pierce
04-19-2018, 08:36 AM
I have done the SB on the intake hoses, heard some pretty good horror stories on those. Also installed the insert in the induction and the peppered fuel nozzle.

cubdriver2
04-19-2018, 09:32 AM
That video sounds more like a fuel related problem. Most intermittent ignition problems that have enough fuel in the system have a backfire when the spark is re added to the excess rich mixture?

Glenn

RaisedByWolves
04-19-2018, 09:54 AM
Maybe check the o rings on the induction tube. If I remember right they are o rings instead of paper gaskets where they attach to the cyl


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stewartb
04-19-2018, 10:16 AM
The tach variation exceeds what I've ever seen from a fuel or induction issue. That looks electrical to me. Like a short or a loss of ground.

MauledbyaCub
04-19-2018, 11:11 AM
It sounds like lack of fuel to me also.
Can you spray starting fluid into the carb to see if the RPM picks up?
(without getting chopped to bits, I mean.......)

As a Yamaha motorcycle mechanic in the 80's we used an Allen Test and later a Sun Exhaust Gas Analyzer on the 4-strokes.
It read CO's (burned carbons) and HC's (unburied hydrocarbons).

A lean misfire would have low CO's (burned fuel) and High HC's because it was getting little fuel which caused a misfire and the unburied fuel showed up as HC's. We'd spray Berryman's carb cleaner or WD40 at the intake manifolds and if the CO's picked up we knew they were leaking. If not, we'd spray it into the intake. If the CO's picked up we knew there was a lean mixture. (Sadly, both Berryman's and WD40 were neutered a decade or 2 ago and no longer work as a starting fluid. And lighter fluid no longer works for tennis ball cannons :(

A rich Mixture would show high CO and high HC.

An ignition misfire would show no CO's but very high HC's.

I have not seen an analyzer like this at an FBO, but I just did a search for "Portable Exhaust Gas Analyzer" and there are a bunch of them on the market.

We also used an in-line spark checker frequently. It provides a gap where you can watch the spark jump inside a clear plastic housing, or watch it fail. You can increase the gap by twisting the housing to the point where the spark can't jump it.

As an aside, I chased a similar issue on my snowblower for a few seasons. When under a big load it would suddenly die. I was sure it was an ignition issue because it cut off without warning, but ultimately discovered that it had a non-vented gas cap on it from another model. The vented gas cap from my lawnmower solved the problem with a twist of the wrist.

behindpropellers
04-19-2018, 11:28 AM
Does it have fuel flow?
Start simple. Vent lines plugged?
If you take the supply line off, how many gallons do you get in 1-2-3 minutes?

stewartb
04-19-2018, 11:32 AM
How does CC power the mags? I don't see any breakers in the CC panel pics.

wireweinie
04-19-2018, 01:05 PM
If it was an electric power issue, I believe you would lose your tach signal. As it was cutting out, you still showed green LED's and numbers on the screen.

Web

Steve Pierce
04-19-2018, 04:17 PM
How does CC power the mags? I don't see any breakers in the CC panel pics.
Two separate buses off the battery with another emergency system powered by a separate battery.

Steve Pierce
04-19-2018, 04:32 PM
After last nights engine run and no change in engine rpm when going through each ignition system i conclude it had to be somethong other than ignition. In the air it sounded like a back fire. When I pulled it through last night I had a soft cylinder. In December during the condition inspection #4 was 70/80 leaking out the intake while everything else was 76/80 or better. Eddie brought my 14MM test hose today so checked compression on #4 and it was 10/80. Borescope didn't show anything that I could see and staking did no good so against everything I have ever read Mike Busch write I pulled the cylinder. Intake valve burnt pretty good. Gonna put an Electronics International CGR30P in while we have everything apart. You can see the water droplets in the second picture from running on the ground and not getting up to temp.
36519
You can see the water droplets in thispicture from running on the ground and not getting up to temp.
36520

36521

36522

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Steve Pierce
04-19-2018, 04:34 PM
Maybe check the o rings on the induction tube. If I remember right they are o rings instead of paper gaskets where they attach to the cyl


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Yep, it has the o'ring at the cylinder head and it looked good when removed.

flynlow
04-19-2018, 05:05 PM
After last nights engine run and no change in engine rpm when going through each ignition system i conclude it had to be somethong other than ignition. In the air it sounded like a back fire. When I pulled it through last night I had a soft cylinder. In December during the condition inspection #4 was 70/80 leaking out the intake while everything else was 76/80 or better. Eddie brought my 14MM test hose today so checked compression on #4 and it was 10/80. Borescope didn't show anything that I could see and staking did no good so against everything I have ever read Mike Busch write I pulled the cylinder. Intake valve burnt pretty good. Gonna put an Electronics International CGR30P in while we have everything apart. You can see the water droplets in the second picture from running on the ground and not getting up to temp.
36519
You can see the water droplets in thispicture from running on the ground and not getting up to temp.
36520

36521

36522

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Yup. Blowing fire back up the intake is what it sounded like. Glad thats it. Do you think the valve might have been snugged a but too tight??..wasnt that cylinder s but soft at annual?


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irishfield
04-19-2018, 05:24 PM
Wow, in all the exhaust valves I've had or seen burnt / cracked I've never seen the intake valve head give up.

PerryB
04-19-2018, 07:20 PM
Yeah, that's a unicorn. Maybe it got a chunk of carbon under it or something along those lines.

tempdoug
04-19-2018, 07:40 PM
Yeah, that's a unicorn. Maybe it got a chunk of carbon under it or something along those lines.


or did the ignition cause it?

PerryB
04-19-2018, 09:47 PM
or did the ignition cause it?
I'm having a hard time connecting those dots, unless it was producing an erroneous spark during the intake stroke on that cyl. and then it would have had one b**ch of an induction backfire. Probably enough to prevent even getting it started. Upon re-think I'm veering away from the carbon theory. I think a piece of the valve rim/margin chipped off and started the degeneration process.

cubdriver2
04-19-2018, 10:09 PM
Interested to see if the valve is the real problem. Not convinced just being burnt would cause what was happening. If it was hanging open it would act as a decompression release/jakebrake and a power loss by recirculating air?

Glenn

Scouter
04-19-2018, 11:00 PM
Steve

This one was in Maine just over the hill from me
Push rod clearance
Jim

http://forum.cubcrafters.com/showthread.php/2582-Titan-engine-problem?highlight=jake

hangarmonkey
04-19-2018, 11:35 PM
Whatís Jon at cubcrafters have to say?


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Might check intake or exhaust valves for damage.


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Gordon Misch
04-20-2018, 01:10 AM
Sticky valve stem, or ill-seated valve. In any case, Eddie has a good mech.

I had a fussy Wisconsin engine on my baler that would sputter and pop and essentially cut out, then always start up again. I never took it apart, but I suspected a too-tight intake valve stem/guide.

Copped out and am using a tractor with PTO now, instead of a team of horses. Embarrassing. Apologies to Amos and Sandy (my team of Shires). They still pull the manure spreader though - - - Like politicians, spreading their own s...... SJ, don't ya dare kill the thread on this! :-P:-P

Steve Pierce
04-20-2018, 06:39 AM
Steve

This one was in Maine just over the hill from me
Push rod clearance
Jim

http://forum.cubcrafters.com/showthread.php/2582-Titan-engine-problem?highlight=jake

Thanks Jim, exactly the same issue and cylinder except I think we have excessive valve clearance as I was able to remove the rocker shaft with my fingers.

I did not measure the valve guide but felt normal. I have an airplane to finish building so I sent the cylinder to the cylinder shop for repairs.

skywagon8a
04-20-2018, 07:01 AM
Steve, While the cylinder is off look inside at the lifter. Look around for any indications of small pieces of metal hitting the crankcase. Years ago I had the mushroom on an intake valve lifter break causing the valve to remain open. The engine quit with no warning over inhospitable terrain in a snow flurry. Then after what seemed like forever it started and ran fine for a few minutes until I just happened to be over an airport when it quit again. All indications were the same as you have found except that there wasn't any rough running. It just quit. In an effort to get it home, I pulled the cylinder, lapped the valve, and in the process of reinstalling the cylinder I spotted some strange marks inside the case. The mushroom on the lifter was broken and jammed into the case. Needless to say a major overhaul was done.

Steve Pierce
05-08-2018, 12:54 PM
Got the cylinder back from having new exhaust guide, intake and exhaust valves and seats ground along with new valve springs. Seems the exhaust valve inner spring was broken and my cylinder guy has seen a lot of those on the ECI cylinders. Ran it up this morning and all is normal.
369473694836949

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Eddie Foy
05-08-2018, 01:45 PM
If it was I, I would install a complete new set of springs.

mike mcs repair
05-08-2018, 02:59 PM
this is a neat video on valve operation...

https://www.facebook.com/EngineLabs/videos/1635369096479973/

Eddie Foy
05-08-2018, 03:26 PM
Helluva difference between 2500 RPM in a Lycoming and 9000 in a Nascar engine. They will actually put a new set of springs in right before a race.

cubdriver2
05-08-2018, 08:48 PM
Helluva difference between 2500 RPM in a Lycoming and 9000 in a Nascar engine. They will actually put a new set of springs in right before a race.

Back in the 70s I had a 302 Z28, that was 60 over with 12 to 1 pistons, 513 rear. 8k was my shift point, went past 9k when I missed a gear. Solid lifters, adjusted valves lash less then 6 times in 30,000 miles before I sold it. My foot was in it every time I was in the seat.

Glenn

Steve Pierce
05-08-2018, 09:14 PM
Be easier to see what is happening now.
36960
36961

Steve Pierce
08-05-2018, 04:17 PM
A little update on this burnt intake valve. The owner talked to Bobby Looper (Titan Product Support Engineer) at v Oshkosh. We already knew that ECI spec'd the O-340 for an MA4-5 carb but that carb wouldn't fit under Cub Crafters cowl so they went with the 10-3678-32 carb like the 160 hp O-320 and changed the throat in the induction and added the peppered fuel nozzle. Bobby says the there is not a jet big enough for this carb and is suppose to send us the drill size to get enough fuel flow on take-off. He also said the old school method of leaning until the engine stumbles and then enriching a bit does not work with electronic ignition. The electronic ignition has a hot enough spark to run smooth with a lean mixture which is how the owner had been leaning it. Said we needed to see 1200 degree EGT'S on take-off and we are seeing 1300-1350.

To add to this I got a call from cubdrvr on Friday. They had been troubleshooting aN RV with a Light speed ignition on one side and mag on the other. Ran rough on the mag but fine on the electronic ignition. They installed another mag and harness and removed the P-lead with no change. Found an intake leak and problem loved which reinforced the info on the electronic ignition having a hotter spark and able to fire a leaner mixture.

Thought others might find this info interesting and useful.

PerryB
08-05-2018, 05:34 PM
Steve, many years ago I had a truck with a hopped up 460 and an Accel dual point distributor. When I removed that system and installed an MSD, it nearly eliminated the need for choke in the morning. The friend who talked me into the MSD system told me this would happen, and of course I thought he was full of it.

Scouter
08-05-2018, 07:13 PM
A little update on this burnt intake valve. The owner talked to Bobby Looper (Titan Product Support Engineer) at v Oshkosh. We already knew that ECI spec'd the O-340 for an MA4-5 carb but that carb wouldn't fit under Cub Crafters cowl so they went with the 10-3678-32 carb like the 160 hp O-320 and changed the throat in the induction and added the peppered fuel nozzle. Bobby says the there is not a jet big enough for this carb and is suppose to send us the drill size to get enough fuel flow on take-off. He also said the old school method of leaning until the engine stumbles and then enriching a bit does not work with electronic ignition. The electronic ignition has a hot enough spark to run smooth with a lean mixture which is how the owner had been leaning it. Said we needed to see 1200 degree EGT'S on take-off and we are seeing 1300-1350.

To add to this I got a call from cubdrvr on Friday. They had been troubleshooting aN RV with a Light speed ignition on one side and mag on the other. Ran rough on the mag but fine on the electronic ignition. They installed another mag and harness and removed the P-lead with no change. Found an intake leak and problem loved which reinforced the info on the electronic ignition having a hotter spark and able to fire a leaner mixture.

Thought others might find this info interesting and useful.



Steve can you take a few pix and document this? would be interested to check my carb when you get it figured out.

Jim

mike mcs repair
08-05-2018, 07:43 PM
Neat thread. I hadn’t read all of it before. Just goes to show what a sticking open(or clinker under it) intake valve will do to you. You don’t just loose that cylinders output power, you loose at least the next cylinders fuel charge and power too, since intake system is pressurized at that point instead of vacuuming


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hotrod180
08-06-2018, 11:55 AM
….He also said the old school method of leaning until the engine stumbles and then enriching a bit does not work with electronic ignition. The electronic ignition has a hot enough spark to run smooth with a lean mixture which is how the owner had been leaning it....

Reminds me of a guy I used to know.
He said he switched to one mag, leaned until just barely rough, then switched back to both and called it good.
I wonder if that would work with the dual electronic ignition?

PerryB
08-06-2018, 01:29 PM
We have a local/older/high-time pilot here that does the same thing.

j5mike
08-06-2018, 02:55 PM
We just put the 4-5 carb on the 0-340 we installed on my supercub. Can not go full rich, full throttle on take off without it running very rough. (acts like its getting way to much gas) We have to lean about 3/4" travel on the mixture. My fuel flow gauge shows this to be about 13-14gph. At no time have I ever been able to get the 15-16gph fuel burn without the engine running rough and stumbling. My CHT are around 325-375 but the #2 cylinder EGT is high. I have to work at it to keep it below 1400. The others in cruise are around 1200. After reading this thread I may be leaning it to much my self. I am running a Vetterman exhaust which I think was designed for the 150hp engine and wondered if that was a factor. At 30 hours and working out the bugs. (with a smile)

Steve Pierce
08-07-2018, 07:17 AM
We just put the 4-5 carb on the 0-340 we installed on my supercub. Can not go full rich, full throttle on take off without it running very rough. (acts like its getting way to much gas) We have to lean about 3/4" travel on the mixture. My fuel flow gauge shows this to be about 13-14gph. At no time have I ever been able to get the 15-16gph fuel burn without the engine running rough and stumbling. My CHT are around 325-375 but the #2 cylinder EGT is high. I have to work at it to keep it below 1400. The others in cruise are around 1200. After reading this thread I may be leaning it to much my self. I am running a Vetterman exhaust which I think was designed for the 150hp engine and wondered if that was a factor. At 30 hours and working out the bugs. (with a smile)
Joe with the Super Legend might can help. He changed his carburetor and has now gone to fuel injection.

SD cubman
08-07-2018, 08:36 AM
J5Mike, the exhaust systems for 320s and 360s are basically the same. The 360 is 1.8 inches wider than the 360. I designed most popular system which was the 360 crossover and placed a cutoff mark on pipes 1 and 2 if it was going on a 320. Vetterman

Steve Pierce
08-07-2018, 08:37 AM
Steve can you take a few pix and document this? would be interested to check my carb when you get it figured out.

Jim
Will do Jim.

AdirondackCub
08-07-2018, 10:44 AM
Steve had one local with some EXTREME fouled plugs. Assume you checked this but it solved our issue locally.

Mike Macon
04-12-2020, 07:43 PM
Steve Pierce -

Does this picture look familiar? We went on quite the journey before discovering the burnt intake valve. It's an 0-340 on a CarbonCub EX. It began with a quick miss, maybe 1 second in duration, and then back to normal. I began trouble shooting fuel flow issues with no luck. I grounded the plane after a few of these occurrences and my mechanic buddy and I began looking at the ignition. We started at the plugs and worked back to the ignition boxes. We had several ah-ha moments only to find no improvement. We contacted Klaus and went through his checklist, and when that was completed, he sent us a loaner ignition box. No luck. You might think it was about time to look somewhere besides the ignition but in our case the miss only occurred on the RIGHT ignition. We were able to get the engine to cut out consistently at about 1800 rpm but only on the right ignition. It sounded like the engine in your video. Ran smooth when we switched to the left. The plane was flown about 150 miles to my mechanic's shop on the "good" left ignition. He changed out both ignition systems with no improvement. The plane was flown to CubCrafters in Yakima for about 500 miles on the left ignition. The engine stumbled briefly on take-off about 100 miles from Yakima for the first time on the left ignition. CubCrafters spent a few days trouble shooting the ignition system and in the process was able to get it to miss once on the left ignition during a ground run. They eventually got a low compression reading on the #1 cylinder, pulled it, and the result is in the picture below. They had never seen this before. I sent them the picture of your burnt valve. I now have about 10 hours on the new cylinder and life is good again.

- Mike Macon

48126

hotrod180
04-13-2020, 09:43 AM
Be easier to see what is happening now.

36961


What engine monitor is that?

CamTom12
04-13-2020, 10:09 AM
Looks like a JPI EDM 350

https://uploads.tapatalk-cdn.com/20200413/8b2179a63b3f224fa65581b84a976cb2.jpg

evroosevelt
04-14-2020, 10:21 PM
Were you ever able to find out the drill size for the 10-3678-32 i have that carb. on a RV6 and have high CHT temps on take off?
Thanks
EV

skywagon8a
04-15-2020, 05:51 AM
Were you ever able to find out the drill size for the 10-3678-32 i have that carb. on a RV6 and have high CHT temps on take off?
Thanks
EV
Are you absolutely 100% certain that your full power, low airspeed, high CHTs are caused by a lean mixture? Have you done tests to confirm that this is the case? Have you leaned the mixture at full power and noted an EGT rise or does the EGT drop immediately as soon as the mixture is pulled back? You may just have an engine cooling baffle error.

hottshot
04-17-2020, 10:48 PM
I had a very minor miss in flight, leaned the engine and determined which cylinder head temp would not come up then traced plug wire to proper coil and found a small spade connector loose, crimped it and solved the problem. Again it was minor.

Had same exact prob. same fix. all good from there.

Steve Pierce
04-19-2020, 07:58 AM
Common issue with the connectors on the coils. The wires are not properly supported across the bottom of the engine. Most of the ones I have had come loose were furtest from the wire supports. Put a dab of silicone at each connector to coil and add the supports. Most of the time when the re is a coil issue it takes out the plug as well.

Steve Pierce
04-19-2020, 08:00 AM
Were you ever able to find out the drill size for the 10-3678-32 i have that carb. on a RV6 and have high CHT temps on take off?
Thanks
EV
I will look but that was for that carb on an O-340 with the peppered nozzle, the sleeve in the induction. Not sure we are talking apples to apples here.

CaseyO
06-02-2020, 12:21 PM
I will look but that was for that carb on an O-340 with the peppered nozzle, the sleeve in the induction. Not sure we are talking apples to apples here.Steve, can you elaborate on the induction insert and nozzle change?

I've been flying a friend's CCK-1865 that will run rough at about 3/4 throttle and is smooth on either side but has a large EGT disparity in cruise. I understand they had a nozzle change for the Marvel carbs but this has an Avstar.

Thanks,

Steve Pierce
06-02-2020, 12:29 PM
Steve, can you elaborate on the induction insert and nozzle change?

I've been flying a friend's CCK-1865 that will run rough at about 3/4 throttle and is smooth on either side but has a large EGT disparity in cruise. I understand they had a nozzle change for the Marvel carbs but this has an Avstar.

Thanks,

Research the service bulletins, instructions and memos on Cub Crafters website. Verify they are current per your serial number. If they are not then I would strongly advice you do so. They were implimented because there were issues. As I have posted before this engine was designed to use a bigger carburetor but that carb would not fit the Carbon Cub cowl. The early Carbon Cubs prior to late 2012 have a Sport Cub cowl that does not cool properly. The ground adjustable cowl flaps, the insert into the intake throat and the peppered nozzle in the carburetor were all attempts to make these engines run correctly and cool in the Carbon Cub Airframes. There is also a 22 degree flywheel timing ring that many have installed to combat the cooling issues.

CaseyO
06-02-2020, 01:32 PM
It appears to have the insert installed. This airplane was a kit that was finished in 2014.

It still has the old induction couplers so I will order the kit for that and see what happens.
Thanks!

Steve Pierce
06-02-2020, 02:02 PM
The induction hose kit is just to eliminate the issues with using heat shrink as an induction hose especially when you have a backfire on a little island and all you have for tools is a Leatherman. ;)
A little weight from real hose and hose clamps is a good compromise in my opinion.

Mike Macon
08-24-2020, 08:36 PM
Steve -

I posted a picture of my intake valve on 4/12/20 that came from my #1 cylinder at 600 hrs. This weekend a experienced the same symptoms and now have another burnt intake on #4 at 650 hrs. You may want to pass this on to your client. The fun may not be over.

Steve Pierce
08-24-2020, 09:31 PM
Steve -

I posted a picture of my intake valve on 4/12/20 that came from my #1 cylinder at 600 hrs. This weekend a experienced the same symptoms and now have another burnt intake on #4 at 650 hrs. You may want to pass this on to your client. The fun may not be over.

What are the particulars on carb, throat insert, nozzle, cowl model, timing ring and engine gauges? That airplane was sold and went to Montana and replaced with an EX2 with 65 hours on it. Had some major baffle problems that I post about recently.

Mike Macon
08-24-2020, 10:09 PM
It’s an EX with the kits purchased from 2013 to 2015 and completed in 2016. Cowl has cowl flaps and I have an EI 30P. No work has been done on the carb. I have done some research on the internet and have only found one other case of a burnt intake besides yours. I would think that if this was not just an isolated manufacturing problem there would be a lot more cases out there. Between RVs and CarbonCubs alone there are a few of these engines out there.

Steve Pierce
08-25-2020, 06:18 AM
I did not realize there were O-340 in RVs. Does SB22 or SI0031 apply? What does the data from the CGR show? The local dealer only uses the 22 degree timing ring vs the 25 and have seen now other issues.

reliableflyer
08-25-2020, 10:37 AM
Hearsay only on my part. One cc appeared to have ignition problems. Turned out to be a broken inner valve spring Another cc had every ignition part replaced down to switch electronic ignition modules and even battery. Problem continued. CC looked at it on site with no luck. Took the aircraft back to Yakima on one mag. I donít know what they did to solve it. CC is aware of some issues that appear to be ignition related. To the best of my knowledge (hearsay only) that was not ignition either.

Steve Pierce
08-25-2020, 11:48 AM
The only ignition issue i have had was a bad crank sensor. Klaus with Lightspeed didn't believe me until I proved to him I ha troubleshot the whole system. he said he very rarely sees a crank trigger go bad. From all of my experience it has been pretty trouble free except when a coil wire gets disconnected and it takes out the plugs.