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Discussion Starter #1 (Edited)
I'm in the process of purchasing an original owner 1983 cx650 custom, it looks great and everything vital works.
It has a misfire in the right cylinder, rendering it unsafe to drive (tops out at 40mph not to mention the risk of piston damage).

I called my local Service Honda and the ingnition coil is unavailable.
Are any of the other model coils interchangeable/compatible?
I have read on an old thread that the gl500 coils would work, is this true?

I need to order this soon as can be, as this bike is now my main mode of transport!!
Thanks and I hope I get her running soon, as with 10k miles and a clean factory paint job, I'll have one he|| of a starter bike.
-Sam
 

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better check your spark plug caps they get water in them and corrode the resistors

next cx650 issue is the spark plug wire shrink from age and pull out at the coil end

check your plug wires are tight in the coil

lastly look under the seat the pulse generator connector is close to the edge of the seat and sometimes the seat cushion can push the connector apart and cause a misfire on one cylinder

the coils dont fail that often but can be easily resistance tested

last but not least what color is the plug from that cylinder as this could be a carb issue to
 

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Discussion Starter #3
Thanks for the informative response,

to give a better understanding of the state of the bike:
this bike has almost always been garage kept and is in pristine cosmetic condition.
That said, I do not know if that has any effect on the old rubber of the plug wires (I assume old rubber is all the same).

I have purchased new plugs and am swapping them tonight; I figured I'd know my culprit if the old ones were in bad shape.
A little carb cleaner could do wonders, I concur haha, as I know that can have an affect on combustion.

Thanks for the tip on the plug wires, the connection on the coil, and the pulse generator connector under the seat.
All things I will check tonight!


better check your spark plug caps they get water in them and corrode the resistors

next cx650 issue is the spark plug wire shrink from age and pull out at the coil end

check your plug wires are tight in the coil

lastly look under the seat the pulse generator connector is close to the edge of the seat and sometimes the seat cushion can push the connector apart and cause a misfire on one cylinder

the coils dont fail that often but can be easily resistance tested

last but not least what color is the plug from that cylinder as this could be a carb issue to
 

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Discussion Starter #4
better check your spark plug caps they get water in them and corrode the resistors

next cx650 issue is the spark plug wire shrink from age and pull out at the coil end

check your plug wires are tight in the coil

lastly look under the seat the pulse generator connector is close to the edge of the seat and sometimes the seat cushion can push the connector apart and cause a misfire on one cylinder

the coils dont fail that often but can be easily resistance tested

last but not least what color is the plug from that cylinder as this could be a carb issue to
It appeared fairly normal to me, blackened but nothing atrocious and the gap was ever so slightly less than it should have been.

There were two different spark plugs in the bike, more or less the same yet obviously not.

Swapped with manual rec NGK 4929 for both.
...but the battery seems to have lost its charge, albeit a new one.

What to do..
Update once I have some power in it.
 

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you mis understood me

take the spark plug cap off the spark plug

unscrew it from the wire

turn it upside down and look down and you will see that the brass end that goes on the plug has a slot for a screw driver

unscrew that take the spring and resistor out and check if corroded or burnt up

re assemble with dielectric grease

SEARCH brass rod mod
 

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Discussion Starter #8
The offending spark plug cap was clean, it looked even better than the "good example" in the photo provided by Wolf (thanks).

My neighbor lent me a battery tender, while I go about my day I grabbed a gas can to tank the bike up.
I'll see how it runs later today.

Also,
FYI the original owner told me he had a similar issue with the opposite cylinder a number of years ago and remediated it by replacing the coil.
I took this with a grain of salt (possible sales pitch).

I'll add a pic as I'm sure it's killing anyone reading to not see it!
Burgundy with a mirror finish.
 

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Discussion Starter #9
My older neighbor came by to help me get the bike started. The carbs seem to be really gunked up and the bike is running rich.

I put some carb cleaner in the gas and used 93 octane, it's runnning a lot better.

If it doesn't improve, I'll take it to Service Honda for a cleaning and tune.

Thanks all!
 

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Discussion Starter #10
As of tonight, my bike is running very well, almost perfectly.
Might just need a tune, but I will persist. Got some Sea Foam and will use it for the next tank up.

The smile on my face writing this right now... hasn't worn off from the ride yet haha
 

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My older neighbor came by to help me get the bike started. The carbs seem to be really gunked up and the bike is running rich.

I put some carb cleaner in the gas and used 93 octane, it's runnning a lot better.

If it doesn't improve, I'll take it to Service Honda for a cleaning and tune.

Thanks all!
Frankly, if you take it to a Honda service center, I would aggressively interrogate the mechanic who does any work to make sure they know about these old bikes.
If the service center does not like to answer questions like that, don't take it there.
The level of expertise at Honda service centers is a big unknown when it comes to servicing vintage bikes. Its not unusual to get a bill for several hundred dollars and your bike is worse off than before.
 

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Discussion Starter #14
a bad (fouled) spark plug will do that as well
I mentioned I replaced the old ones with Factory Spec NGK's (for $5, why not). The old ones looked fine though.

Basically the bike stumbles/falls on its face a bit when I reach the peak power rev range (6k-8k).
 
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