Perplexing ignition problem

[bmeyer6472]

My Vision recently developed an ignition problem, and I have been unsuccessful in fixing it. I have cut the rev  limiter wire, and replaced the TCI (thanks Lucky), but the problem persists. The engine will start, but misses intermittently. When the miss occurs, the tach reading drops slightly. Oddly, when I remove either spark plug wire from the corresponding plug and attach it to an external spark plug, the engine runs on one cylinder without missing, and the external spark plug seems to spark normally, with a nice blue spark. It runs OK on the front or rear cylinder without a noticable miss, but misses pretty badly when both plug wires are attached to the plugs in the engine. Anybody have a clue as to what is going on?  ???
Thanks!
Bob

[Lucky]

these new symptoms remind me of what QBS allways advises: make sure the coil connectors are clean & tight. I believe he had a similar problem & that fixed it...  it kind of makes sense, if the connectors are corroded or loose then both coils will be fighting each oter for juice. disconnect one (less spark resistance on a plug not under cyl pressure) and the other fires fine.

in the same vein, poss the plugs have gone weak. I have seen plugs that while visually they look fine, & gapped correctly will not fire properly under culinder pressure.

I strongly advise you go thru EVERY electrical connector on the bike, if you haven't done so yet, and clean & tighten all of them a coating of diaelectric grease or at least vaseline is reccomended too. don't forget to do the relays as well. open them up & spray them out with WD-40 or contact cleaner.

it's a very tedious task to be sure, but keep in mind that the wires aare now 20+ years old, and to quote Rick G: "they've given a lot of good over the years, now it's time to put the good back into them" (lots of good quaotable people on here, lol.)

hth, --Lucky

[Paul_Jungnitsch]

Lucky is probably right. The only thing I can add is the original plug wires are kind of a goofy screw together design. I had trouble with missing when one had come slightly apart (still looked fine from the outside IIRC). May want to check those connections are tight and clean as well, might be easy to substitute with a couple off a car for testing purposes.

[bmeyer6472]

Good advice guys. Thanks, I'll try your suggestions. I HATE it when my stuff doesn't run right. I haven't checked the coil mounting and grounding yet-it's raining, so tomorrow I'll give it a go. I'll be sure to post if I find the problem.

[QBS]

The tach gets its signal from one of the spark coils low voltage input wires.  The wire divides before it gets to the coil and one wire continues on to the coil and the other one goes to the tach.  The fact that the tach shows variation in rpm would indicate that the problem could be a bad connection at the spark coil.  Clean and grease all low voltage spark coil connections.  Even if this doesn't solve the problem, it still is worthwhile preventative maintenance.  Keep us posted.  God bless us all.

[bmeyer6472]

The possibility of the coil primary wiring being the culprit seems very likely, after hearing about it. I am almost looking forward to finding out if that is the problem!  ;D
This is a great site - thank you all for your helpful and friendly advice.
Bob

[jim ransom]

sometimes the ignition sensor wires that exit the stator cover will split the insulation where it exits the cover, 1 or both  coils  could be grounding out.

[bmeyer6472]

I thought I had found the problem - bad connections at the spark plug - the screw together connectors were severely corroded inside where the little hollow screw is that snaps over the spark plug, and the resistance was through the roof, so I fixed that. Had a hard time getting the bike to start, then it started on one cylinder, then caught and ran smoothly at 3000 rpm for several minutes. Thought I had it fixed, but NO! Soon as I reduced the engine speed to about 2000 - 2500, it began misfiring again, with the tach cutting out each time. I checked the primary connections to the coils, checked the primary and secondary coil resistance, rechecked the pickup coil resistance - everything looks good. Unplugged and reseated all the connectors, even in the headlight housing, pulled and tested the spark plugs, they are OK, checked the ignition wires, OK. Swapped TCI's, no difference. Checked the fuse box, all OK. I'm out of ideas and pretty close to out of patience. I know I must be missing something, as the engine runs good at 3000 and above, but I'm thinking that I'll let it be for a while, until my back recovers, anyway! Thanks again to all who tried to help me with this problem. If I ever get it figured out and fixed, I'll post.
Bob

[Lucky]

try disconnecting the YICS & plug the ports, it may be leaking....

[louthepou]

Has it been a really long time since it ever worked well under 3000 rpm? If it ends up not being electric, then it would have to be something else (i.e. dirty valve not seating well enough, etc)

Louis

[bmeyer6472]

It had been running perfectly until this problem surfaced a couple of weeks ago, and it has been ridden, at least some, each month. The problem is almost certainly electrical, as the tach is affected when it misses. One thing I forgot to mention, is that even at 3000 RPM or more, (in neutral) when it is running smoothly, if you blip the throttle, it will sometimes hesitate before revving up, and when it does this, the tach heads for zero before it catches and speeds up. I haven't a clue. ???

[Lucky]

Have you eliminated the side stand circuit as a culpret? this should be one of the first things you check.  slide the Black/White wire at TCI 6-prong plug connector out of the connector. you'll need a pin to do this, or Radio Shack sells a took kit for a few bucks.  if this cures the problem, check the side stand switch for continuity, or the interlock relay.

also try this:
hook your meter back up to the pick up coils & do a "wiggle test".  unplug the coils from the TCI and hook the meter, set on ohms, to the pickup coil leads, then wiggle the wires at the case. look for an intermitent open connection, then do the same thing, but with one of the meter leads hooked to the case (ground) look for a short.  do the same thing for the coils.

another thing that just struck me is to check your key switch & on switch, as well as the clutch & safety interlock systems the same way. high resistance in these circuits can cause the bike to act like it's cutting out as well.

we'll track it down yet!

[bmeyer6472]

Heh, heh!  You're trying to aggravate my backache! ;D I may have some time to try some of your suggestions today - thanks again for the input. I also think I'll replace the fuse box under the seat - it's showing its age for sure...
Bob

[QBS]

Play with the rocker kill  switch and see if you can alter any of the symptoms.  Better still, unplug it and then devise a jumper that bypasses the switch and make the bike think the switch is in the "Run" position.  My rocker switch has given some grief over the years.  Cheers.

[MotorPlow]

My rocker kill switch almost stranded me on 2 occasions.  Both times, I was able to continiously flip the switch back and forth for about 5 minutes and then started right up.  After the second time, I pulled it all apart and cleaned up all the connections inside.  No problems since.

Timing doesn't get mentioned much with the Vision.  What's the possibility that bmeyer's timing is off, thus causing the misfire at low RPMs.  Just a thought....

~Chris F.

[Lucky]

Unless he's got a cam chain problem, timming isn't a possability. there is no timming adjustment, it's all handled electronicly from the TCI & he's swapped that...

--Lucky

[QBS]

In the interest of nipping potential confusion in the bud, V initial static ignition timing/spark advance is fixed by design. That is, it is set by the location of the TCI pick up spots that are bolted to the left engine cover.  There is no provision for any type of adjustment.  In the Vision, cam timing is a function that is completely unrelated to ignition timing.

Interestingly, if a person wanted to create more initial spark advance in search of higher power, it it is possible to turn the pick up point assembly attachement holes into ovals and then mount the assembly a few degrees earlier regarding crankshaft rotation.

This could be a dangerious game as the exact amount of advance would be difficult to know.  Too much and you get ventilated pistions.  Even so, for a knowlegable tuner seeking more race track power, this is one area of engine modification that would seem to be a good place to look.

God bless us all.

[bmeyer6472]

Not fixed yet, but some progress, maybe. Replaced the fuse box (thanks Lucky!) Also checked the side stand cutout - not the problem. Went through ALL the connections again, did wiggle tests, blah blah blah. When I try to start the bike, it catches right away on one cylinder (I can't tell which), and if I nurse it a bit, it will then start  to run on both, at least at 3000 revs or above. I am not positive, but I think the ignition system may put out more voltage at higher RPM than when cranking to start, so I may have a  bad spark plug - I checked them both and they LOOK OK, but...

I remember years ago we ran an old Chevy 1 1/2 ton truck backhoe conversion that would not run unless the spark plug wires were OFF the plugs, but near enough to arc to the plugs. Supposedly the extra resistance of the arcing caused the voltage to go up enough to fire the plugs, (?) I don't know the real reason why it worked, but it gives me an idea. One of the spark plug connectors on my Vision had burned out the little internal resistor, and the internal resistance was way up in the megohm range - the other one was about 20K ohms, which I think is normal. This bad connector might have been my original misfire problem. I foolishly replaced both of these internal resistors with solid brass rod, not considering at the time that the ignition system is designed to run with these resistors in place. This may be causing interference with the ignition module, but my main thought is that if the TCI doesn't see the correct resistance, it may not fire correctly, at least at low speed. This may not make any sense at all, but when the bike shops open on Tuesday, I'm going to go buy a couple of new connectors and see what happens. I'll probably install new spark plugs also, but maybe not, as they seem to work OK at higher revs. One thing at a time is probably best.
I'm gonna feel really dumb if all this was caused by something as simple as a spark plug connector - probably just wishful thinking, tho. I'll post Tuesday or Wednesday with the result. Thanks to everyone for your interest and your suggestions.
Bob

[ProfessorRex]

Definately install new plugs!  It's easy as pie, cheap, and eliminates one possible problem.

[Lucky]

is it an 83? with 83 carbs? if so I know what's wrong...