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Author Topic: Honda EM400 Generator  (Read 2344 times)

Sluicebox

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Honda EM400 Generator
« on: November 18, 2014, 12:28:37 AM »
Hi Folks, This as you can see is my first post here. We have a mining claim and camp on it for at least 30 days at a time. I have a em400 honda that I can't get spark on. Pretty sure it is the coil but would like to make sure. I disconnected small wire to coil to isolate it and still no spark. I was hoping that someone here had a link where I could view the shop manual for this gen. I need this for charging Dewalt XRP 18V batteries. Have been eyeballing a couple of Honda EX 800W Generators on Craigs List, $200-$275 Price sounds fair, and from what I can tell are pretty quiet and efficient. Thoughts? BTW that 400 I can't find the fly wheel, I pulled both end covers off and all it has are two aluminum cooling fin assemblies one on each end. One has the points that I cleaned and set, the other end is just the recoil start. Unless it is between the gen head and motor I'm lost., Thanks

Lou Schneider

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Re: Honda EM400 Generator
« Reply #1 on: November 18, 2014, 01:04:45 AM »
Welcome to The RV Forum!

Here's a link to the EM400 Owners Manual and at the end is an electrical schematic. 

There are several shop manuals available on Amazon and Ebay for about $30-40 each.

The EM400 uses points and condenser feeding an ignition coil the same as an automobile engine.   It's not a magneto ignition like other small engines - ignition power comes from a winding on the generator and goes through the points to the ignition coil.  In fact, there is no flywheel - the generator armature provides the momentum to carry the engine between power strokes.

You'll need the small wire connected between the points and the ignition coil or you'll get no spark.

The kill switch kills the ignition by shorting the high side of the points to ground.

First thing I'd check is the condenser across the points - if it's shorted it will short out the points just like the kill switch and you'll get no spark.  Try disconnecting it for a test, if you get spark it's shorted and you'll need a replacement before you burn up the points.

Hope this helps!
« Last Edit: November 18, 2014, 01:14:15 AM by Lou Schneider »

Sluicebox

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Re: Honda EM400 Generator
« Reply #2 on: November 18, 2014, 05:56:40 PM »
Thank you Lou I will try that, I thought I was going crazy not seeing a flyweel lol.

tonyreynoso415

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Re: Honda EM400 Generator
« Reply #3 on: August 02, 2017, 07:13:45 PM »
Hello
I know this is an old post, could you figure out why your generator wasnt making spark??

Lou Schneider

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Re: Honda EM400 Generator
« Reply #4 on: August 02, 2017, 07:30:06 PM »
We'll never know.  Sluicebox hasn't been back to the Forum since making his last post in this thread.

tonyreynoso415

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Re: Honda EM400 Generator
« Reply #5 on: August 02, 2017, 09:22:30 PM »
Hello Lou
I'm in the same boat,  can't get spark it on my EM400, I bought a new point breaker and a new condenser, do you know what should be the air gap???

Lou Schneider

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Re: Honda EM400 Generator
« Reply #6 on: August 02, 2017, 09:32:00 PM »
Hi Tony, Welcome to The RV Forum!

Download the Owners Manual from the link I provided above ... page 23 shows how to set the points.  Apparently they're set by adjusting them so they open at a certain location as the flywheel is rotated, not an actual gap width.

tonyreynoso415

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Re: Honda EM400 Generator
« Reply #7 on: August 02, 2017, 09:38:55 PM »
thanks
I'm going to try that

tonyreynoso415

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Re: Honda EM400 Generator
« Reply #8 on: August 05, 2017, 06:40:45 PM »
hello
i changed the breaker points and condenser with no luck, still not getting spark, then i checked continuity to ground in the other cables please see the attachment

1 cable to on/off switch, only continuity when is in off
2 cable to ignition coil, continuity with ground
3 cable to rear winding, continuity to ground
4 cable to condenser, no continuity to ground

is this ok to have continuity to ground on cable 2 and 3??

thanks

Lou Schneider

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Re: Honda EM400 Generator
« Reply #9 on: August 05, 2017, 09:01:12 PM »
That all sounds normal.  If the generator's been sitting for a while, it may have lost the residual magnetism that lets it start generating power when the rotor turns.  No magnetism = no output from the stator ignition winding = no spark.

Get something like a 6 volt lantern battery.  Connect the (-) side to the generator chassis (the ground lug works), then test the ignition coil by briefly touching the (+) side to the cable going to the ignition coil.  This should generate a spark across the spark plug if the ignition coil is good.

If you get a spark, the next step is to flash the generator by connecting the battery (+) for a second or two to the stator ignition coil wire, the one going to the rear winding.  This will make the stator ignition coil into an electromagnet and impart some magnetism into the generator core.

Now reconnect the wires as they were and see if you get a spark.
« Last Edit: August 05, 2017, 09:07:18 PM by Lou Schneider »

tonyreynoso415

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Re: Honda EM400 Generator
« Reply #10 on: August 05, 2017, 09:06:59 PM »
a 12v battery would be too much???

Lou Schneider

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Re: Honda EM400 Generator
« Reply #11 on: August 05, 2017, 09:08:09 PM »
Try it if it's what you have, but be quick!  The advantage to something like a lantern battery is it self-limits the current to a safer value.

You could do the same thing by putting a light bulb in series with the 12 volt battery (between the battery (+) and the connection points).  Just thinking out loud here.
« Last Edit: August 05, 2017, 09:10:18 PM by Lou Schneider »

tonyreynoso415

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Re: Honda EM400 Generator
« Reply #12 on: August 05, 2017, 09:39:59 PM »
thanks a lot for your help Lou.
I did what you suggested, but i didn't get any spark at the spark plug. and I tried with 2 brand new spark plugs. then,I assume, the ignition coil is the problem???

Lou Schneider

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Re: Honda EM400 Generator
« Reply #13 on: August 05, 2017, 10:12:13 PM »
Sure sounds like it, though to be honest I'm just guessing at what kind of voltage the stator ignition coil provides to the spark coil.  Were the points open?  If they were closed, the battery would just short to ground instead of going through the coil.

Take the generator down to a Honda motorcycle dealer and see what they have to say.  Chances are good Honda used a similar ignition system on one or more of their motorcycles of similar vintage.
« Last Edit: August 05, 2017, 10:16:44 PM by Lou Schneider »

tonyreynoso415

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Re: Honda EM400 Generator
« Reply #14 on: August 05, 2017, 10:19:46 PM »
because of my schedule at work is kind of hard for me to take it to a dealer. I just found a new ignition coil for 30 bucks. will have to wait until it arrives and replace it to know if it was the problem.

tonyreynoso415

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Re: Honda EM400 Generator
« Reply #15 on: August 10, 2017, 08:19:29 PM »
Thanks a lot Lou. I replaced the ignition Coil and it started at the first pull. I put some VP small engine fix it fuel, ran for 5 minutes and I will let it overnight and try it again tomorrow.

Lou Schneider

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Re: Honda EM400 Generator
« Reply #16 on: August 10, 2017, 08:58:58 PM »
Congratulations!

 

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