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CM-6 Gas Engine problem

Old 06-19-2013, 03:00 PM
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Night Scream
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Default CM-6 Gas Engine problem

Hi everyone:

I've been encoutering this problem in the past and though it was just me.. but recently this is getting out of hand..

I'm in mid flight doing aerobatics or just flying around and out of the blue the engine dies on me.. after 15-30 flights in the ignition dies without any warning..

Thank fully i haven't had a crash except some minor scracthes [been lucky] but still.

And i've had the ignitions wrapped in heavy density foam to prevent vibration, regular foam. Have placed the ignition in the firewall like it shows and i've seen in many gas planes in the forums and in the field, also have placed the iginiton inside the plane making sure no RF signal interfere's with the other electronics. And i use a 4.8 volt battery just for the ignition, tried a regular switch, heavy duty switch on them as well

I've changed the hall sensor, spark plugs, cleaned the carb rigolously, changed the ressistance that goes in the cap before the spark plug and even bought a carb kit from a lawnmower shop thinking that was it.

It will give me an sputter trying to start but nothing happens.

But if i put a brand new ignition it instantly turns on and it's set for like i set 15-30 flights and again they die.

What's going on?? Not to mention is see that all gas engines using this CM-6 spark plug all ignitions are made by RC Excel?? IS there another brand that sells these iginitions?

Is this a common problem??
Old 06-19-2013, 03:59 PM
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chris923
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Default RE: CM-6 Gas Engine problem

I think you ignition is getting to hot wrapped in foam.
Old 06-19-2013, 04:17 PM
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Night Scream
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Default RE: CM-6 Gas Engine problem


ORIGINAL: chris923

I think you ignition is getting to hot wrapped in foam.
I also though so years ago and then just placed a small square just the size of the ignition on the bottom of it using foam to prevent the vibrations.

And still the same problem persists.. after those 115-30 flights they stop working be it in the air while performing aerobatics or even after landing .. after those flights have bpassed its a lotery when it will go..
I allways carry 1 brand new ignition with me in my field box.. because everytime this happens.. i try turning the motor on again and nothing happens or it just sputters trying to turn on but dies..

I place the brand new ignition and instantly it turns on with no problems at all.. It's extremely frustrating not to mention becoming quite expensive..

I've been flying for quite over 20 yrs and since i switched to gas engines this is a constant problem.. With glow if the engine stuttered i switched the glow , maybe fine tune the needle a bit and was back in the air. but with this I quite honesly don't know what's going on.
Old 06-19-2013, 05:02 PM
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Truckracer
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Default RE: CM-6 Gas Engine problem

A point of interest and a few things you can try. First, the RCexl ignition has recently been redesigned. You may want to try the new version.

CH has returned with a new owner and here is the website. You might want to try this ignition.

http://ch-ignitions.com/

There is also a new ignition available called RCxp. This and the whole RCexl line is available from RC Extreme Power @

http://www.rcextremepower.net/

Have you tried just replacing the plug cap when the engines stop running. Internal failures in the cap can stop an engine in its tracks and they are cheap to replace.

Old 06-19-2013, 05:31 PM
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speedracerntrixie
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Default RE: CM-6 Gas Engine problem

What is your plug gap? I seem to remember hearing something about excessive gap being rough on the coil.
Old 06-19-2013, 05:33 PM
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Default RE: CM-6 Gas Engine problem

Just get a CH-Ignitions unit and be done with it all. They are really good. Plus they stand behind their products too.
I just use a rectangular piece of velcro to secure the ignition module, that lets it get some air to help keep it from overheating.
If you do some radical aerobatics, you can use a velcro strap to help keep it in place too.

Old 06-19-2013, 07:50 PM
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Default RE: CM-6 Gas Engine problem

sub
Old 06-20-2013, 12:45 AM
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3136
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Default RE: CM-6 Gas Engine problem

Show us a pic of your setup.
Is it possible heat is building up in the cowl and overheating the cdi?
Is there baffling in the cowl?
Is the cdi near the muffler?
Old 06-20-2013, 01:55 AM
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pe reivers
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Default RE: CM-6 Gas Engine problem

What engine? What ignition brand? Were did you buy the ignitions?
Ignition in foam, with tie wraps? Loosely or tight?
This may be important information before we all dumbASSume it is RCexl that is mounted correctly.
Old 06-20-2013, 03:01 AM
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Lifer
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Default RE: CM-6 Gas Engine problem

Sounds like a gradual overheating of the engine. Richen it a bit first, and perhaps a little bigger exit for the heated air.
Old 06-20-2013, 03:05 AM
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Default RE: CM-6 Gas Engine problem

It would be nice to get some hard information on the components in his install to make a more educated suggestion as to what might be the problem.
Old 06-20-2013, 03:49 AM
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ahicks
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Default RE: CM-6 Gas Engine problem


ORIGINAL: karolh

It would be nice to get some hard information on the components in his install to make a more educated suggestion as to what might be the problem.
X2....
Old 06-20-2013, 04:08 AM
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Default RE: CM-6 Gas Engine problem


ORIGINAL: pe reivers

What engine? What ignition brand? Were did you buy the ignitions?
Ignition in foam, with tie wraps? Loosely or tight?
This may be important information before we all dumbASSume it is RCexl that is mounted correctly.
I'll try to get a pic from one of my planes showing how i have the ignition.

I'm using DLE 30 both brand new rear carb versions and 1 side carb. which has over 250 flights in it And i got them in 3D planes [extra 260, MX2]

I've been using DLE ignitions from tower hobbies, RXexl bought from hobbyking or bob's hobby shop in orlando florida.

All brand new and they have all lasted the same.

Set up i got i got after numerous configurations of testing to see what's been going on.. is:

Cut a square of foam just the size of the ignition bottom and hold it in place with 2 tie wraps [plastic one's] and i have either the iginition inside the plane near the gas tank or in the cowling held in the same way. and i just tighten it so that they will not move but not excessively tight, but never loose enought for them to fall out of place.

All my cowlings i make extra big holes in the bottom to make sure air get's in and out fast for maximum circulation of airflow.. I don't have any baffles in my cowlings

the spark plug gap i got for the dle 30's i think is 26 or 28 gap of the spark plug.

About the cap from the ignition.. I have purchased and allways got extra of those CM-6 Spark plug cap kit's that come with the cap, the silicone boot and the ressistance and sometimes they work other not, but when they work it's the ssame they last 15-30 flights and again die.

This has been an on going problem with these ignitions since i switched to them.. The engine's are superb and very reliable.. but the ignition.. that's a different story.


Might have to try those 2 new iginitions the CH and the RcXp you guys mentioned
Old 06-20-2013, 04:21 AM
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ahicks
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Default RE: CM-6 Gas Engine problem

Are you using the later ign. modules capable of handling voltage up to 8.4 volts? If not, what are you using for batteries to power the module? Are you using anything like a regulator or IBEC in the circuit?
Old 06-20-2013, 04:31 AM
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Default RE: CM-6 Gas Engine problem


ORIGINAL: ahicks

Are you using the later ign. modules capable of handling voltage up to 8.4 volts? If not, what are you using for batteries to power the module? Are you using anything like a regulator or IBEC in the circuit?
Well the last iginitions i bougth from bob's hobby shop are just rcexl says 4.8 to 6volt.. bought them about um.. 1 yr ago i bought 3 of them.

I use a regular 4.8v battery back raging from 1000 - 1500mah connected to either a regular switch or a heavy duty switch before connecting to the ignitions red battery cable.
Old 06-20-2013, 07:03 AM
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Default RE: CM-6 Gas Engine problem

I agree with PE, that if we don't have some clearer details we all are just wizzing in the wind Sounds like you are doing everything right but 15-30 flights per ignition unit is not normal. I have only replaced 1 unit recently under warranty and 1 hall sensor in the last 3 years on 4 DLE's My guess is you are getting high voltage into the units somehow and killing them.
Old 06-20-2013, 07:16 AM
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pe reivers
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Default RE: CM-6 Gas Engine problem

My guess is that the ignitions are not RCexl at all, but imitations. At least not those from HobbyKing. Xu Liang does not sell to HK.
I see no fault in the setup. Plug gapped to 0.5mm?, Plugs maybe? Chinese CM6 imitations are known to fail without warning.
Old 06-20-2013, 07:22 AM
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Default RE: CM-6 Gas Engine problem

I'll try getting a pic tonight when i get home and post it later..

Would a voltage regulator on a regular 4.8volt battery reduce the chances of it getting a high voltage?

Or would these new ignitions that as mentioned before can handle up to 8.4v also solve this?
Old 06-20-2013, 07:34 AM
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Default RE: CM-6 Gas Engine problem

Absolutely no need to regulate a 4.8 volt battery. The fact that different brands of ignitions are all prone to failing and in the same way it is reasonable to assume that it is something that is common to your ignition circuitry that is causing the problem. Some pictures would be very helpful.
Old 06-20-2013, 07:48 AM
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Default RE: CM-6 Gas Engine problem

The regulator is a very good idea only if you use a higher voltage battery, but not with a 4.8V battery. If your problem is battery voltage related with a 4 cell battery, then too high a voltage in not an issue, but too low a voltage is very likely.
Pete
Old 06-20-2013, 08:38 AM
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Default RE: CM-6 Gas Engine problem


ORIGINAL: pe reivers

My guess is that the ignitions are not RCexl at all, but imitations. At least not those from HobbyKing. Xu Liang does not sell to HK.
I see no fault in the setup. Plug gapped to 0.5mm?, Plugs maybe? Chinese CM6 imitations are known to fail without warning.
The plugs i'm using i've purchased from tower hobbies or my local hobby shop..

The last plugs i got where 1 original DLE spark plug and another honda cm-6 plug [haven't tried this one yet]
Old 06-20-2013, 10:41 AM
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Default RE: CM-6 Gas Engine problem

Throw out the DLEplugs. they are junk and stick with an original NGK CM-6 you can order them on line from many places and should only cost about $5 ea http://www.quickieparts.com/spark-pl...w-engines.htmlyou may just have a bunch ignition units you did not need.
Old 06-20-2013, 12:42 PM
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pe reivers
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Default RE: CM-6 Gas Engine problem

+1 with Raptureboy.

Rcexl ignitions are known to operate well up to 7V since day one! Maybe with shortened lifespan, but surely not 25 flights. I operate the old types on 2S LiFe battery to be sure of a strong spark. Others have done the same without ill effects.  I use either NGK CM6 (used in Honda generators, not a Honda plug) or RCexl ICM6 iridium plugs. Both are good. The Iridium plug is slightly colder than NGK CM6.
Old 06-20-2013, 02:13 PM
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Default RE: CM-6 Gas Engine problem


ORIGINAL: pe reivers

+1 with Raptureboy.

Rcexl ignitions are known to operate well up to 7V since day one! Maybe with shortened lifespan, but surely not 25 flights. I operate the old types on 2S LiFe battery to be sure of a strong spark. Others have done the same without ill effects. I use either NGK CM6 (used in Honda generators, not a Honda plug) or RCexl ICM6 iridium plugs. Both are good. The Iridium plug is slightly colder than NGK CM6.
Where can you get those iridium plugs from? First time I've heard of them
Old 06-20-2013, 02:23 PM
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Default RE: CM-6 Gas Engine problem

I just checked the brand new plug I bought last time from bob's hobby shop in Florida is a Honda NGK japan Cm-6 plug..

I'll be using this one after I change to another ignition on my mx2 as the one I had stopped working today.

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