1981 CM 400 coil help

S

strat

New Member
Hi Guys, I need a coil for my 81 Honda cm 400. I have looked online at them but I'm not sure what I need. What ohms should I use? What will work with my ignition? Do I need to replace my ignition as well as my coil? If so, what ignition and coil combo should I use and who from? This bike has really been kickin my butt, although during this problem finding process I have removed my switch, took the wiring harness off and apart to remove the controls for the turn signals, warning lights and that stupid gauge beside the speedometer. Really cleaning up the wiring. I'm going to remove the clutch and neutral switch as well. I have to figure out what to do with the 2 wires coming from the starter solenoid that go to the clutch switch on the bars and any help there would be great too. Please forgive me if I have too much stuff in this post. I really need some advice on this. Thanks in advance!
Roy
 
Hey there, the first thing that jumps out at me about tour post is that there really wasn't a reason given for needing to replace the coil. I assume that your bike won't start. Could it be a bad wire or sparkplug?

Sent from my DROIDX using Tapatalk 2
 
sorry about that, I have no spark. I tested the coil for the correct resistance at the wires going into the coil and my ohmmeter read just like I had touched the two ohmmeter leads together, needle went all the way to the right and when I tested the plug wires with the same meter the needle almost didn't move at all so I don't even know what the reading really was.
 
The easy answer is to ebay a new coil and buy new sparkplugs. Its about $70 to buy everything. It may just be bad sparkplug cap or wires. Those are significantly cheaper. So it might be worth your time to investigate. Then again you could be out riding had you replaced everything.
Since I cant tell you exactly what your meter readings mean so I will leave that to someone else.

Sent from my DROIDX using Tapatalk 2
 
Wooooah, hold on. The CM/CB400 coil can be replaced with a GM model.

http://www.hondatwins.net/forum/viewtopic.php?f=60&t=7571&sid=df8734cd7b865c9b3c3aafdac2c09573

Check that bad boy out. Cheaper and better.
 
NvgtrWiggles, thanks for the info!! I just called the auto parts store and it will cost me $36 and change! man I was so worried. As you can tell I didn't have a clue how to buy a new coil, not to mention the fact that I didn't have the cash. ($200.00) So, let me say thanks and just in case I forgot, THANKS!!! (can you hear me now?) ha,ha :)
 
No problem! You pick up this kind of info just browsing around bike forums all day. There's so much cool shit being build, and I absolutely love seeing clever mods like this.
 
Yeah man, me too! this is a cool mod no doubt. I'm gona pick up that coil today, money has been kinda tight lately. One thing about the bike being down, I have managed to remove the instrument gauge, clutch and neutral switches, turn signals, relay, fuse block, ignition switch and a whole shitload of wire. I took the wiring harness off and tested each wire, no shorts or damaged insulation anywhere. I still have to make a bracket to hold the tail light, I might screw that to the underside of my seat so I could remove the rear fender. I need a few nuts and bolts and I can put it all back together. I'll post pics when I install the coil and let you know how it works.
Till then,
Roy
 
Well, that didn't work. I don't know whats wrong with it now. I started another post, this time its "no fire". Lets see what happens.
 
You need to test each component in the electrical system. Check the stator, check the switch on the handlebar control (now that you've modified it, make sure it's right), etc.... It's in the Clymer if you have one. The stator resistance values can be very specific to each model. I don't think that there's any way to test the CDI, so you have to eliminate everything else and then replace the CDI if all else is good.
 
do you have a manual?
ck primary; two leads off coil, about 2-5 ohms
secondary; two high tension lead ends without the plug caps about 10-15k ohms
bad plug caps usually do not inhibit sparking but should be replaced if not correct- either 5k or 10k ohm on electronic ignitions.
ck kill switch, ignition switch plus all connections if coil ck's out ok
joe@vcycle
www.joesvcycle.net
 
Thanks for the tips guys. I have a Clymer for it and have done most of the tests. Nothing seems to be wrong. Could be my ohmmeter is incorrect. I've had it for a long time and only used it for continuity and volts. I'll get a new one today, I hope I find the problem soon. It's making me crazy >:(
 
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