The easy way to check is to take a spark plug out of the cylinder, leave it hooked up to the wire, ground out the base to the engine and then hit the starter for a brief second. If you get spark, the ignitor is functioning normally. Be careful not to get shocked. It's usually not dangerous but the sudden zap could cause other issues due to startle factor. No spark, it could be the ignitor but it could also be a wiring problem going into or coming from the ignitor. As I said in reply to this question in your tach thread, the IC ignitor either works or it doesn't. Semiconductors don't have an in between.
Chances are you wouldn't get a freq (Hz) reading if the ignitor were bad.
If the ignitor does turn out to be the problem, check ebay or salvage yard for a used one that works. It's much cheaper that way and they are super easy to replace. It bolts onto the back of the battery box with a couple of bolts. Just unplug the wiring sockets, undo the bolts, reinstall the new one, reconnect and yer done. 10 min job.

 

Ok Jim, thank you. Let me follow up with some more questions, if you don't mind.

) Is it really possible for the ignitor to be bad at only 6,000 miles? For background, the bike was left outdoors by PO #1, and then sat unused in the garage of PO #2 for about 4 years. Ok, on this one - I guess that mileage isn't the only factor, because electronic components break down over time whether they're used or not. But I'm still curious as to average life span is on these things.

2) Prior to dropping off the bike I had been getting a Hz reading off the front coil. If the ignitor was truly bad, would it still be possible to get a reading off of the front coil? I thought I read in the Clymers that a bad ignitor might still send out a weak signal, which I imagine would generate a Hz reading even it it wasn't adequate to fire the plug - but i'd like someone to confirm or refute that.

3) If the Ignitor really IS bad, are there other/better replacement options besides the OEM ignitor? I was looking on http://www.regulatorrectifier.com for a replacement, but didn't see one for the VN750.

4) about how hard it is, it doesn't sound bad from what you described. When I looked at the Clymer, i got the impression that I had to remove the gas tank. I'm glad it's an easy fix.

 

Mine sat out in the Georgia and Texas weather for who knows how long before I got it. It had about 7500 miles on her and I got to ride her 30 days before she crapped out hard core on me. A small ball bearing came loose inside her and the acct's acted up from having sat for so long. The ignitor was just fine however. ( I hope I didn't just jinx myself).

No, you don't have to remove the gas tank to get to the ignitor, just the seat. The ignitor sits on the back of the battery box toward the rear fender and EPA spider.

The spark check will tell you if the ignitor is weak. However, all it does is send the impulse to the coil. It's the coil that generates the spark. The ignitor simply tells it when. You can compare the spark you get with the front with the back using the same process. I'd still trace the wiring before concluding it was the ignitor. There are some tests you can run on the ignitor to see if it's within spec as well.
AFAIK, the only two sources for the ignitor are either used, or OEM from a dealer or online distributor like Ron Ayers or Bike Bandit. Neither Electrosport or Rick's or the website you looked at carry ignitors.

 

Sounds like the smart thing to do would be to tell them to just close it up, pay them for the tires & oil changes, and do the rest of the problem determination myself. Thanks for all your input Jim.

 

I have learned over the years that I'd rather screw something up myself than pay someone else to do it for me. At least I learn something from it and when I do get it right, it costs less too. That's why I do my own wrenching on all my vehicles, unless they're under warranty. Then I let the manufacturer pay for it all.

 

hey Pogg, I was having the same problem on my rear cyl. traced it back to a broken wire coming off of the pickup coil. you might try pulling the plastic sheath off and check the wire where it goes between the startor cover and the transmission. that is where mine broke...just spliced it back together fairly easy...also check out the thread titled "Rear Cylinder No Spark" This thread goes into great detail of how to trouble shoot al of the ignition system...taking time on every part involved starting with the coils and working back to the pickups...It realy sounds like your pickup coil has a broken wire... that would explain the tack jumping....also you might check the sparkplug wires. if the ICB is shot...there is one listed on eba right now for a whole lot less than 400 bucks

click pic to go to item on ebay

 

What Slim said!!!!

 

An old wise motorcycle mechanic told me it is very rare you see a coil go bad in a bike.

 

No, but the wires leading to and from a coil can go bad.

 

Ok, I've read and reread Slim's post on Rear Cylinder Not Firing. So today I went up to my friend's shop and went through the ignition system.

• Wires: Not in great condition. I'm ordering or making new ones (probably ordering). They each read about 4.5K in resistance, so they weren't broken, but the insulation was very brittle. Who knows what could happen when they get hot and the resistance goes up?

• Ignition Coils: The ignition coils Primary read 2.2, and 2.3 Ohms. Can you believe I forgot to check the secondaries while I was there? I did.

• Ignition Pickup Coils between B/R & B/W was 488, and between B & B/Y was 478. Within the acceptable ranges.

However, when I checked the resistance readings for the IC Ignitor (out of circuit), I get the following results...

• 4 Pin Connector: It appears that this controls the pickup coils. All readings are within range.

• 6 pin Connector: From the diagram, looks to control the Ignition Coils. Almost every reading is out of range. In fact, I get some very strange results!
  Pins 3-4, are supposed to be infinity. Sometimes I get infinity, and sometimes the resistance increments by 2M ohms every second.​
  Pins 3-6, are supposed to be between 0.9 - 1.7Kohms. Instead, the resistance oscillates back and forth between 8.2K ohms, then 225.4 ohms, then 8.2K, about 1 x per second!!​
  In fact, several of these readings oscillate or increment. My somewhat limited electronics background implies that there is a leaking capacitor and/or an unstable IC somewhere in the circuit. The results are so screwy, I dont know how the bike was running at all.

Net result, I'm glad I have a new Ignitor on order. I ordered 4 NGK Irridium plugs from Amazon @ 7.32 each. Now I want to find a source for prefab plug wires, and I'm going to pickup Bulldog's R/R bracket so I can relocate while I'm alread in there.

 

IIRC you need a special Kaw meter to test the ignitor. I don't think a standard meter will give you correct readings.

 

Are you sure Chris? All of the other readings checked out against the book, and the book didn't say anything about using any special meter functions or settings. Just strait resistance readings. I'll be interested to see if readings from the new ECM compare to the book, or if it gives screwy results like the current one.

 

How dirty are the blade connectors coming out of the ignitor? If they aren't clean, the sporadic readings could be caused by an intermittant connection due to a dirty connection with the meter probes. I know mine are pretty crudded up but the bike runs fine.
If you still strongly suspect the ignitor, check ebay every so often and one will pop up. As you know, a new one runs about $400.

 

How dirty are the blade connectors coming out of the ignitor?

They were actually pretty clean, plus i took an emory board and cleaned them further. I even used a connector socket connected to the probe, so that I would have a good contact.

 

hey poggpj, I forgot half of the ts proceedures of this never made it to the forum...mastrtech and I spent a good deal of time on the cell phone...take testlight and check the signal wires going into the Igniter Box.....but I am 90% sure it is your Ignitor and not the pickup coils. and yse a MM can test the IB

 

Excellent. Thank you for the feedback. I'm tempted when the new ignitor arrives, to see if any of those "variable" measurements occurr. I wouldn't think that a multimeter could induce a damaging voltage into the module. If that were possible, it would mean that it couldn't be tested with a meter in the first place.

 

Final results

Ok, here is the result. Received the new Ignitor today. Tested it before I installed it, and got the same whacky, incrementing readings. Installed it, and absolutely the same. Front cylinder still not firing. So my local shop was either, 1 incompetant or 2 lying, or 3 - i received a brand new faulty ignitor out of the box. This week I'm going to pick up a spark test light.

 

i think you need to inspect those pickup coils better...if the IB doesn't fix it...the pikupcoils is the only other thing it could be...get a testlight and test the pickupcoils

 

Hey there Slim,
How do you test the pickup coil using a test light. I've done the meter test on them and they checked out that way.

 

At this point, have you pulled the plugs and spark tested them against the engine to visually see if they have spark? It's easier than testing with lights.
I still think it's a wire issue in the system.

 

Hey Jim,
Yep - took the plugs out tonight and checked them against the engine for spark. First of all, it looks like both front plugs have never been fired. They look brand new and are wet with fuel.

Rear plugs fire fine. Front plugs get a small bit of spark for about a second, then the spark stops entirely. So I started replacing the wires, and the threaded coil cap is so brittle it split in half!

Anyway, since it's both front plugs, I suspect the coil. Is there a way to test the coil separate from the plugs?

 

I think you would be better off just replacing the wires first and see. The coils don't go out very often on our bikes. (One of the few electrical parts that doesn't). If the plugs spark after you replace the wires, it's probably because they got so brittle the cores fractured someplace causing an open. If the spark was weak, the current probably has to jump across a gap in the wires or it's getting dumped to the engine case somewhere. I used to get a great arc and spark light show from my right front plug cap where it touches the metal casing on the throttle cables. I had to use a bunch of electrical tape to stop it and I really need to replace my wires and plug caps on both cylinders.
I don't know of a way to test the coils separatly outside of ohming them out with an ohmmeter. If they pass the resistance test, that's about all I know how to do short of grabbing a terminal while the engine is running and seeing how much of a jolt you get. I don't recommend this however!! Slim may have some other tricks up his sleeve though.

 

PoggiPJ,
All I can say is I must be one of the lucky ones then, because I did have one of the coils go out on my 85 700. According to the book there are two ways to test the coil

OR

My coil went because the junction box (as it was inspected closer upon removal) had some acid drip inside and arc between the connections inside. The only evidence from the outside was a tiny hole behind the rubber on the outside of the JB.

 

Charlie, that was some excellent documentation. Thank you

I couldn't test the spark arc gap, since there isn't a spark to arc.. lol

But I did test the resistance. The primary is fine. 2.2 ohms. The secondary, however is 43.3 Kohms. That is way out of range. Since neither of the front plugs are firing, I'm inclined to think it's the coil.

So now the question is, do I go with a new OEM, or with aftermarket like Dyna. What do you recommend? Also, if I upgrade the front coil, must I also upgrade the rear? That rear one looks like it can be a real PITA to replace.

 

The rear isn't too bad. I took mine out so I could reposition the EPA spider in the back.
You could also get a used coil from someone here or on ebay.
There was a link awhile back where someone replaced their coils and they came as a set, IIRC.

 

Hi Jim. I checked eBay. None at the present time. I saw a pair of Dyna's on DennisKirk, but the hole orientation doesn't work for our bike. $147 for a pair.. The OEM coil (21121-1124) is available on RonAyers for $75.