No spark on 2 and 3

[Gene]

(85 650sc nh)

1st suspect coil
2nd suspect coil wire.
3rd wiring/ign kill switch
4th ign module

So far I'm having problems getting an ohms reading on the (wires) with my dmm.
Has anyone managed to separate the wire from the boot?
I've tried pulling and twisting, no luck.
Also,  I know the wire itself is solid core, is there a resistor built into the boot?
If so, I'm going to guess it's at least a megohm

[Larry Fine]

Try swapping coils and wires with the 1-4 coil.

[Pete in PA]

Each boot has a 5k ohm resistor. So each circuit has 10k ohms. Definitely try switching them. See if the problem moves.

The wires unscrew from the boots.  Inside each boot is like a big wood screw.

[Larry Fine]

The wires unscrew from the boots.  Inside each boot is like a big wood screw.

If I'm not mistaken, the same is true with the coil ends.

[Bob H]

(85 650sc nh)
No spark on 2 and 3

What happened before the failure?
One day it is OK, next day no start?
Did you have the tank off - something bumped?
I know you have a 650, but for my 750 that would indicate the left coil as you are sitting on the bike (runs plugs 2 and 3).
Are you sure the hot wire to that coil is good? Not the signal wire, but the 12 volt constant supply?

So far I'm having problems getting an ohms reading on the (wires) with my dmm.
Has anyone managed to separate the wire from the boot?

Again this is for the (similar) 750, but my manual has an ohm test with wires removed from the coil (just unscrew the retaining cap, comes right off). That is either going to be in spec or not. The probes push against the inner metal cavity and that part is simple. Were you able to do that part of the test?

Assuming the coil (without wires) reads OK, then the next thing of resistance at the end of the leads is just what it says. There is no need to remove the boot. If the coil was OK and the reading at the end of the boot is wide open (no continuity, infinite ohms) then you just need to either replace your wires (or as Pete says you could unscrew the boot & resecure it - I have seen that on youtube but mine were very secure and solidly connected to the wire).

Also,  I know the wire itself is solid core, is there a resistor built into the boot?
If so, I'm going to guess it's at least a megohm

In terms of diagnostics, it doesn't matter. If you have stock wires to spark plugs, and are using a manual that states an acceptable range of resistance at the end of those wires, that range would assume whatever resistors were present at the factory.

[Gene]

 Hi everyone,  thanks for the helpful suggestions.


So far, it looks like a bad secondary on the coil, no reading at all. The primary is ok. I haven't been able to get a reading from the wires either, after removing them from the coil.

I'm still not sure how to remove the plug ends, they are on very tight. Peering inside, the visible part can unscrew, so I will try that.

Now, I know I will need to get a new or good used coil.

[Bob H]

OK so your primary reading is OK

So far, it looks like a bad secondary on the coil, no reading at all.

Is this where you took your measurement? I am interpreting this as "open circuit" which is infinite resistance - is that what you are saying?

I haven't been able to get a reading from the wires either, after removing them from the coil.

I'm still not sure how to remove the plug ends, they are on very tight. Peering inside, the visible part can unscrew, so I will try that.

1). if the plug ends don't come off, it is possible they are not original.
2). Both 2 and 3 spark plug wires went bad at the same time??
3). In terms of the coil, I would just try to check these readings. I am sure your 650 is similar to these 750 late model specifications.
These screen shots are from a Clymer manual, which for my model is often more helpful than the Honda factory manual.

[Gene]

Bob, so I did remove the wires and check the coils terminals. Also I can't get a reading on either wire, which makes me think that I'm not making contact inside the boot even though I've used a screwdriver to establish a connection. I don't think that's working. I think I will try to establish a connection with a plug, I can't believe that both boots have a bad resistor.

BTW, yes, sometimes the aftermarket manuals can in some ways be better. (I've got the factory manual)

I've got a copy of the Clymer manual on the way.

Your comments on separating the boot from the wire is noted, I'm just afraid I'm going to damage it if I'm not careful. And I'm sure they are original.
Ok, update. One boot is bad. I tried the coil again, I am getting a reading now. This points out that I made a mistake, plug wire boot two is the bad part.
Now, where do I get a replacement boot/wire?
Maybe I can find a parts bike on Craigslist.

Thanks everyone.

[Bob H]

Ok, update. One boot is bad. I tried the coil again, I am getting a reading now.

So your coils are good?

Now, where do I get a replacement boot/wire?
Maybe I can find a parts bike on Craigslist.

This reminded me of a response I got from my boss in 1978 when I was talking about getting used brake shoes.
He frowned and started talking about not buying used condoms.

In the big picture, wires aren't that expensive and are a "tune up" item.
My recommendation after I went down the rabbit hole is to get these copper ones
https://nighthawkforums.com/index.php?topic=359.msg3054#msg3054

That is a "Napa" brand. I got mine on Ebay, new in box. You can order them from Napa. They are listed for tractors and farm equipment because the OEM style copper stranded wire is not allowed to be sold for street legal car - motorcycle use. (electrical interference issue)

The plug ends are factory assembled. Very solid, that end of the wire-boot will not come loose.
You cut them to length per existing wires and fiddle with the coil end connection as I show in that other thread.

[Gene]

Bob, I think I'm going to go the Napa route. Thanks.

[Bob H]

I'm going to go the Napa route. Thanks.

I was very impressed with the quality of that wiring kit.
The one odd thing is connecting the coil end of the wire after you cut it to length.
As I mentioned in that other thread, you don't need the rubber boot they provide to slide over a car distributor - so I cut the end off that rubber cap and it fits snug on the wire's insulation.



I used some tire lube to make it easier to move around.



You will re use the cap that screws onto the existing coil.
There is an odd ring that has a choke hold on the old wire, I suppose to keep it dry.
In this photo I managed to get mine off intact as I was still figuring out what I needed to reuse.

If I had to do it again, I would just cut that ring off to enable removal of the bigger piece that screws onto the coil.

You may have some of those things that screw onto the top of a spark plug - as I mentioned in that other thread I had to add them to the top of my spark plugs on the 750. I assume your 650 may need them as well.
https://nighthawkforums.com/index.php?topic=359.msg3054#msg3054

[Gene]

BTW, since 1 and 4 go up and down together, same as 2 and 3, it shouldn't matter which plug each coil feeds, as long as the correct coil feeds 1 and 4, or 2 and 3. Why? One will fire as a "waste spark".

[Pete in PA]

You still have to match up correctly. The pairs must stay together.