Basic Ignition System Question

I just bought a 82 Maxim with 48000 miles. Suprisingly enough, it runs pretty good. However, as a basic tune up, I got some new spark plugs and installed them. Now, keep in mind that this is my first motorcycle and I am a diesel mechanic and have worked on cars quite a bit. I had noticed earlier that the spark plug cable seemed unable to detach from the coil, which I found odd from what I have experienced with Otto cycle engines.

Question 1: Can you change just the cable and not the coil?

Now, that was fine, but when I went to tighten down the new plugs, the spark plug cap came off in my hand. Just slid right off! At the time I was quite concerned. After doing some research I see that the cap is not integral to the spark plug wire and it might not so strange that it would come off.

Question 2: How are the ignition wires on a motorcycle assembled? More specifically, is mine broken? If so, how do I fix it?

I have been looking at this forum for many days now, and I want to thank you all for what you do regarding these great bikes.

 

you're not "supposed to" be able to replace the wires without replacing the coil, but where there's a will, there's a way . . .

rickomatic does a walk through on coil surgery here: http://xjbikes.com/Forums/viewtopic/t=11221/highlight=coil+surgery.html

i believe you can also get spark plug wire splices that basically screw in like the caps between two sections of wires.

the wires are just stranded conductor with insulation around the outside - pretty basic.

the caps should just screw on - sometimes they don't want to cooperate. if you have enough slack you can cut a bit of the end of the wire off and start with a "fresh" end.

you have 4 cylinders and 2 coils, so 2 cylinders are fed off one coild and 2 cylinders are fed off the other (i believe it's 1 and 3 off one and 2 and 4 off the other, but could be wrong).

if you have an ohm meter you can check the resistance through the coil between the spark plug caps for cylinders 1 and 3 (or 2 and 4). that'll tell you if you have a broken wire. (and tell you if you need new coils, too).

hope this was helpful, and - since i'm no expert, trust this information at your own risk - hopefully someone will chime in and correct any misinformation i've given you - as far as i know, i'm right, but - hey, i've been wrong before, ya know?

 

That was quite helpful thank you!

To recap to ensure I understand, the plug caps SCREW on to the exposed wire, so I need to strip the insulation off approx. .5 inches (?guess?) to rescrew the cap on. If I do not have enough room for that, it is possible to splice the some more ignition cable onto the existing cable, though a new coil with cables would be the best and most expensive option.

Any ideas what may have caused it to slide off other than age and chance? In other words, how do I prevent it in the future?

 

no - you do not strip off any insulation. inside the plug cap is a threaded piece of metal. that will screw into the spark plug wire. sometimes they don't want to screw in - usually because the hole in the end of the wire is too big (cuz it's old) or there's not enough actual metal wire in the end for the threads to bite into.

if you shine a flashlight down into the spark plug boot, you might be able to see the threaded "screw."

you should be able to feel it tighten up and not want to turn any more - just like if you put a real screw into your wire.

if you just yanked the boot off the end of the wire instead of screwing it off, that might have messed up the inside of the wire - i'd bet you should only have to cut off 1/4" or so and it will thread back in.

ngk carries spark plug wire splices: http://www.parkeryamaha.com/ngksparkplugwiresplice.aspx but the picture doesn't really illustrate the "threading in" process i'm talking about.

i'm pretty sure the splices are basically just a piece of threaded material (just like what is in the boot) with a protective covering.

 

That splice is probably suitable for use on anything, ... including Personal Water Craft.

If the end of the Spark Plug Wire is "Damaged" from having been pulled-out of the Plug Cap ... leaving hardly any of the Spark Plug Wire Core to screw the Plug Cap on to ...

Try this old trick:
Strip a short length of Household Circuit Wire and take a Copper strand of the Wire and insert it in the end of the Spart Plug Wire.

Tape the Spark Plug Wire to the shaft of a Phillips Screwdriver.
Make sure its lined-up straight.
Feed the Copper Wire in as far as it will go by hand.
One it stops ... try holding the Copper Wire 1/4 Inch from the end with needle nosed pliers and tap it in tight.
one the Copper is in ...
Clip the end.
Heat shrink the end.

Screw the Plug Cap into the Plug Wire and take a good bite on the Copper Core you inserted.

 

They are indeed... and you know Chacal stocks them. Part number HCP2789.

Once the wire is cut (the suggested distance from the coil is 4 inches) one slides the cap, a beveled plastic piece, and a rubber sleeve onto the wire. (Some silicone grease might not hurt here.) Then the main body is pressed onto the wire, with the recessed spike making contact with the conductor. Slide the pieces on the wire back down and snug down the screw-on cap. Repeat for the other side of the wire.

 

Day7a1, You most likely can replace just the wires, but it involves a great deal of work. I'm fairly close and can assist (I've spare sets of coils and can swap with you in a pinch).
Schmuck, are you almost done with that ignition wire/coil surgery post? It would be the perfect solution to this issue.

 

I believe it's 1-4 and 2-3

 

Thanks Robert. I'll keep your offer in mind. Actually, I was just curious about the spark cable, there was nothing wrong with it other than the cap being loose. I examined, reattached and op tested it and everything works fine. My diesel engines don't have spark cables, so that part of it is still a little strange, along with carburetors.

The most pressing thing at the moment is a valve adjustment.

Perhaps this is best left to another thread, but how cost effective is it really to do the work yourself, rather than take it to a shop that already has a selection of shims and the proper tool? Keep in mind that I have NO clearance, so it's not like I can just calculate up the shim I need and buy just that one (per valve, of course). It would be a long process of trial and error, which I am mechanically up to, but perhaps not logistically.

 

You'll save a small fortune doing what you can by yourself.

Regarding the "No Clearance" Shim.

Find a Valve that's Loose.
Pull that Shim.
Read the Value of the Loose Shim

Pull the Tight Shim.
Substitute the LOOSE Shim for the TIGHT One.
Take a Clearance Reading using the substituted Shim.
Use the Reading obtained with the substitute for determining the Shim you need to correct the Too Tight Situation.