XJ700 1985 Spark Plugs Wires

XJFolks,

Say I would like to replace my Spark plug wires. Wondering if I have to purchase new coils in order to get the new wire. Plugs seem to die often leading to hard cold starting. If I replace the plugs....bang, fires right up.

Any assistance would be greatly appreciated.

-John

 

what is happening to the plug is it burnt or fouled?

 

I'd pull the plug caps off of the coil wire, they unscrew. Then check the resistance of the coils. You'll have to find the correct resistance in your manual.

If the coils check out ok, then check each plug cap's resistance. They should be 5k ohm if they are stock. If they check as well, try trimming about ¼" off the end of the wire and re-install the plug caps.

 

I had this same issue. I had a shop install new wires for me because I couldn't figure out how to do it without replacing the coils, but they did it somehow -- so it must be possible. Anyway, it didn't help.

What did help was cleaning my carbs... this was a few years ago, so I don't recall if it was running lean which made the plugs overheat and die (they looked ok on the outside, not melty or anything) or running rich which fouled them over time (that seems more likely).

It also didn't help that I had a marginal battery at the time... when starting, the starter sucked up all the available power, leaving the ignition system with a very weak or even nonexistant spark.

You might also make sure you have the right heat range of spark plugs... maybe go one hotter.

 

If the Bike runs fine after a Hard Cold Start ....

I'd be investigating the condition of the Start Enrichment Circuit.
Fuel Bowl Jets
Siphon Tubes
Passages

Most people who have difficulty with Cold Starting find that there was an issue in the Enrichment Circuit.
Once resolved ...
Varoom-bubbub bubbub bubbub bubbubububububub.

 

Actually when I remove the plugs, they don't look all that bad but found that simply installing a new one seems to be enough to get it running. So was thinking the plugs were going bad. Once it is running it is fine and performs nicely. I did trim the spark plug wire on one end but it is kind of short now. It actually fell off in my hands, so I trimmed the wire.

Was thinking if it is possible to replace the complete spark plug wire between the coil and the plug caps.

Is this possible?

Oh, I did take the carbs off and cleaned this spring. I like the bike, when it runs good, it is really a nice cycle.

Much Appreciated.

-John

 

It's possible, but difficult at best. See, here's the thing: the wires don't simply plug into the coil; they're more or less molded into place. If you look around, you'll see detailed procedures for grinding away part of the coil body to free the wire up so it can be pulled out. RickCoMatic has one such writeup here on the site somewhere.

As it can be difficult and time consuming, it's best done only if you know there's a problem in the wire itself. RPGoerlich has the right idea -- take the plug caps off and stick a multimeter, set to the 1k scale, across the two wires. You should read about 11K ohms. If it reads higher, you've got a bad coil. (I had one spit out 80K not too long ago.) If you read normal but get an intermittent contact, then perhaps there's a break in one of the wires.

 

The BEST Write-up and Illustrated "Do-It-Yourself" Coil Wire Surgery is here:

http://www.xs11.com/forum/showthread.ph ... readid=137

No matter how you cut it ... you are going to have to spend some time putting New Wires in your Coils.
This process works.

There are a few Short-Cuts to try before you start removing the Case Material on the Coils:
"Stuffing the Plug Wire" -- Strip some Romex and get a piece of naked Copper Wire a few inches long.
Stuff it right in the end of the Plug Wire and tape it in until it goes in as far as you can send it.
Clip the end.
Add some Heat Shrink to the end of the Spark Plug Wire.
(A double-coat making the end nice and tight)
Re-attach the Plug Cap getting a NEW BITE into Wire that is going to provide the whole charge.)

 

Given the effort to what you need ... I would think that the best thing to do would be to purchase some aftermarket coils and wires, transferring the plug caps/boots from the old cables to the new so you can maintain the OEM boots/connection to the bike.

The coils on these bikes are notoriously weak in the first place. Replacing them with better/more efficient coils should greatly help things.

 

Rarely a need to.. Ever.. change the spark plug wires, they are stranded Copper., not carbon..Real hard to damage. The Spark plug boot on the other hand ..the excreale ones that 'sorta fit' onto the threaded end of the spark plug, are instantly in the Trash Bin IMO
IF you seriously feel the nbeed for new plug wires, NGK sells a screw on wire splice gizmo specifically for the purpose. Like all NGK stuff it Works.
Find and Buy a few.
Also while here IMO, the OEM yama coils are actually quite decent quality.. it's they don't normally fail, in my experiences

 

Everyone,

Thank You for the great feedback.

Very much appreciated.

I like this bike. It is fun to ride. Purchased some new tires for my XJ last week. Old ones had cracks. I let the bike shop change the tires because I could not get the axle out of the back wheel. The bike has only 8k+ miles. I purchased new. With the price of gas, thinking can enjoy riding my XJ and save some $$.

-John

 

I know you'll be happy and have a great time riding that Bike when you get it all smoothed-out and purring.

That the Bike has only 8,000 Miles is a BIG Plus.
You probably won't encounter a MAJOR Problem.
BUT,...
Even though it only has those few miles on it,...
Some of its parts are going to fail because 27 years happened and the Seal or the Steering Head Ball Bearings and the Fuse Panel and other Rubber Parts were only expected to last 12 or 15 years.

 

coil wire replacement isnt that bad... i like the write up that was on here when i did mine... basically very similar except you dont grind out ou cut a chunk out and replace it and glue it back down... looks pretty clean when your done