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1981 Honda CX500 Custom
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Discussion Starter · #1 ·
I recently bought a 1981 CX500 for super cheap and the guy I bought it off of told me it had a bad pulser coil but that it wasn't a big deal. I got it home and did some diagnosing to figure out what all was bad and found that I had no spark to my left cylinder and a weak spark to the right. Naturally, I went to see if it was the ignition coils and found that the wires coming from the CDI were both reading 2.5 volts. I continued to research and found that my issue could lay in the stator so I did resistance checks using a very handy picture I found off this forum, I concluded that 3/5 and 4/5 were both giving no readings however the rest of the leads were in the normal range. I was told that my stator and LH adv coil were bad so I went ahead and ordered the stator (the engine is coming out to be painted anyways and the stator was cheap so it wasn't a big deal). I am now stuck with this, what am I to do about the LH adv coil? I was unable to find any for sale to replace so is there any way that I can repair it? it is my understanding that it is not "required" to run but there will be a loss of power due to incomplete combustion and poor timing, is this true?
 

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3/5 is testing the left advancer and 4/5 is the left low speed pulser. Neither are a part of the stator. Your only options for these is used parts or install a Rae-San Hall effect kit. The Rae-San does not use any of the old coils and is powered from 12 volts so also doesn't use the low or high speed coils which are a part of the stator.

If the ignition timing is not advanced that side will develop less power and the exhaust may become hotter. That would not be good for the engine, to say nothing of how unbalanced the left and right would be.
 

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1981 Honda CX500 Custom
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Discussion Starter · #3 ·
3/5 is testing the left advancer and 4/5 is the left low speed pulser. Neither are a part of the stator. Your only options for these is used parts or install a Rae-San Hall effect kit. The Rae-San does not use any of the old coils and is powered from 12 volts so also doesn't use the low or high speed coils which are a part of the stator.

If the ignition timing is not advanced that side will develop less power and the exhaust may become hotter. That would not be good for the engine, to say nothing of how unbalanced the left and right would be.
Bear with me as this is all new to me. Is the system an extension of the CDI or replacement? also it effectively cuts out all function of the stator besides charging the battery right?
 

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The best one to answer that question and to help you decide which system would be best for you is Ray. Rayman

Send him a private message.(conversation).
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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the guy I bought it off of told me it had a bad pulser coil but that it wasn't a big deal.
He lied to you. It's a major failure.

...and the stator was cheap...
I doubt you found a cheap G47 stator. Maybe a G8, without the extra CDI functions.
If you switch to a Rae-san ignition to bypass the bad pulsers, a G8 will work just fine.
 

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From my experience with a friends bike, Ray ships pretty quick. However things do get hung in customs at times for no obvious reasons. He also stands behind his stuff if issues arise. what stator did you buy link maybe
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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It'll run terribly. The imbalance between cylinders will put extra stress on everything, so it won't remain in its current state while you blissfully ignore the problem. Fix it sooner rather than later.
The Rae-san system will be the most expedient solution. If the current stator is adequately charging the battery, you won't even need to drop the engine.
 
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'84 CX650E that is evolving into a GL500
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Welcome to the forum. Please add your location and your bike's model and model year to your profile so that you don't have to remember to tell us every time and we don't have to keep asking when you forget (see Forum Settings link in my signature).

And welcome to the world of antique vehicle ownership (they own us, not the other way around). Your bike is about 4 decades old and the ignition issue aside, the Previous Owners may or may not have done the maintenance necessary to keep it safe & reliable so it is highly recommended to download the Factory Shop Manual for your model (available through the CX Wiki - link in my signature) and go through all of the service procedures, regardless of whether your bike has reached the specified mileage.
I also recommend looking on all rubber parts with suspicion because rubber does not age gracefully. Check the date codes on your tires and replace them if they are over 5 years old no matter how good they look & feel (old rubber simply cannot flow around the irregularities in the asphalt well enough to grip, especially if it is cool or wet). If your bike still has the original rubber brake line(s) (should be replaced every 2 or 3 fluid changes = 5 or 6 years) I recommend shopping for modern stainless braided ones (they last practically forever and double the life of the fluid). And don't forget things like the rad hoses and the boot between the engine and swingarm (they can crack on the bottom where you don't see it).

Honda used 2 different ignition systems on this family of bikes. The early models had Capacitor Discharge Ignition (CDI), which is powered & triggered by special windings on the alternator's stator but later models have the Transistor Amplifier Ignition (TI or TAI) which is powered by the charging system.
Models with TI include the CX500T, CX500E, CX500C ('82 only), GL500/I and all CX/GL650. All others (including your '81 CX500) came with CDI.
The CDI uses Pulsers that are attached to the stator while TI has Pulse Generators which are under the timing cover at the back of the engine and have no connection to the stator. Perhaps the guy you bought it from read about replacing the pulse generators on an '81 GL500 and thought the CX would be the same...
Or perhaps he knew what was involved and that's why it was "super cheap"

At any rate, the problem is yours now. If you decide to make it live again a modern Rae-San ignition is probably your best bet.
 

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1981 Honda CX500c "Black Widow"
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I recently bought a 1981 CX500 for super cheap and the guy I bought it off of told me it had a bad pulser coil but that it wasn't a big deal. I got it home and did some diagnosing to figure out what all was bad and found that I had no spark to my left cylinder and a weak spark to the right. Naturally, I went to see if it was the ignition coils and found that the wires coming from the CDI were both reading 2.5 volts. I continued to research and found that my issue could lay in the stator so I did resistance checks using a very handy picture I found off this forum, I concluded that 3/5 and 4/5 were both giving no readings however the rest of the leads were in the normal range. I was told that my stator and LH adv coil were bad so I went ahead and ordered the stator (the engine is coming out to be painted anyways and the stator was cheap so it wasn't a big deal). I am now stuck with this, what am I to do about the LH adv coil? I was unable to find any for sale to replace so is there any way that I can repair it? it is my understanding that it is not "required" to run but there will be a loss of power due to incomplete combustion and poor timing, is this true?
I have a LH pulser available, just took mine out with the replacement of a G8 stator. Kept the right pulser in for the alignment mark. DM me if you wanna buy it. Otherwise I definitely recommend getting the Rae San hall effect kit.
 
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