Electrical issue - no spark

[brianszubinski]

Bike would run fine, hit a bump, stall out. sometimes would not start at all, move the bike a couple of inches, start right back up. You could not sit on it without it just stalling out. Ran great until you sat on it, then died.

This lead me to.....

I have determined I am not getting juice down at the spark plug. I have pulled the plug and tested it against the frame - no spark. I also hooked up a light tester to the frame and then tested both the green and black wires that go into the "connection box" and the cable the connects to the top of the plug. When attempting to start the bike, neither of these wires are live. Which ones should be? if i remove the connection and the wire going to the plug, and just test these two connecting wires - black and green - should one of them or both light?

Second part of the question is (since i am assuming they should be lighting) where would i track both these wires back to? I think there is a short somewhere close and under the seat, but everything is wrapped in black tape so I am wondering where these wires lead to, and how/where I can trace them back to for testing.

Any help would be appreciated,

Brian

[motormike]

Determine the year, make, and model of your scooter and find the service manual in the link provided below.
Refer to the wiring diagram and resolve your wiring questions.
Hope that helps...

http://hondaspree.net/wiki/index.php5?t ... ce_Manuals

[brianszubinski]

The bike is a 1985 Honda NQ50 Spree. I have the guide open and the wiring diagram. When I hit the starter to start the bike, should black/yellow light up a light tester? I have gone through the wiring. The bike has everything going right, except 0 spark. I went up into the starter, engine stop switch and if I ground out the yellow/red the bike attempts to start. is that correct? Irregardless, the B/W coming out never lights the light tester. Should it?

The ignition coil has a green and B/Y - the green I am assuming is ground. The B/Y goes from the coil up to the CDI - is there a way to test the CDI? I have applied the electrical tester to all 5 wires going in, and nothing would get the test lamp to light. That is what led me up and into the gauges for the B/W wire, because that should be the power input for the CDI - right? can someone confirm that and let me know if I am missing anything?

[martynkim]

The bike is a 1985 Honda NQ50 Spree. I have the guide open and the wiring diagram. When I hit the starter to start the bike, should black/yellow light up a light tester? I have gone through the wiring. The bike has everything going right, except 0 spark. I went up into the starter, engine stop switch and if I ground out the yellow/red the bike attempts to start. is that correct? Irregardless, the B/W coming out never lights the light tester. Should it?

The ignition coil has a green and B/Y - the green I am assuming is ground. The B/Y goes from the coil up to the CDI - is there a way to test the CDI? I have applied the electrical tester to all 5 wires going in, and nothing would get the test lamp to light. That is what led me up and into the gauges for the B/W wire, because that should be the power input for the CDI - right? can someone confirm that and let me know if I am missing anything?

Your assumptions are correct, I also think your CDI has gone bad.

Problems described like this can also come from the stator/pickup or even the harness itself.

Is this the bike that the brake switches were bad? perhaps more is going on there.

Mouse is the electrical genius... Hopefully he will chime in soon.

[brianszubinski]

Thanks for the input. Yes, this is the one i put the too large of a fuse in. I know its 2 problems, but my thoughts is that they are unrelated. I think there has to be a faulty wire or loose connection at play here, so i have been trial and erroring my way through.

here's one. if i connect the B/W and the Y/R underneath the gauges, nothing happens, but when i put the starter switch in the off position, the bike attempts to start.

I will be replacing b/w next, in the hopes that it is the culprit.

[brianszubinski]

OK. i decided not to replace anything. Before i get too far ahead of myself. Bike would run, and bumping or shaking all of the electrical on the right side would cause the bike to stall out. Especially when bumping the ignition coil, so I figured a loose wire was there. But could an ignition coil slowly go out? and if so, everything would want to start but I would have no spark correct? Is there a way to test the CDI, so know it is the ignition coil for power - since that is the last piece before the plug....

[motormike]

OK. i decided not to replace anything. Before i get too far ahead of myself. Bike would run, and bumping or shaking all of the electrical on the right side would cause the bike to stall out. Especially when bumping the ignition coil, so I figured a loose wire was there. But could an ignition coil slowly go out? and if so, everything would want to start but I would have no spark correct? Is there a way to test the CDI, so know it is the ignition coil for power - since that is the last piece before the plug....

I really think you are fighting a connection problem.
Page 14-8 in the service manual gives some CDI info, but not a complete chart for testing...
I have recently experienced a complete loss of spark on my NS50F.
The fix was swapping out the CDI and instant spark.
The FAILURE was NOT gradual, but instant.
Coil does not usually act as you described either...

[martynkim]

OK. i decided not to replace anything. Before i get too far ahead of myself. Bike would run, and bumping or shaking all of the electrical on the right side would cause the bike to stall out. Especially when bumping the ignition coil, so I figured a loose wire was there. But could an ignition coil slowly go out? and if so, everything would want to start but I would have no spark correct? Is there a way to test the CDI, so know it is the ignition coil for power - since that is the last piece before the plug....

I really think you are fighting a connection problem.
Page 14-8 in the service manual gives some CDI info, but not a complete chart for testing...
I have recently experienced a complete loss of spark on my NS50F.
The fix was swapping out the CDI and instant spark.
The FAILURE was NOT gradual, but instant.
Coil does not usually act as you described either...

All due respect, I have had intermittent issues with coils. From my experience that can be the problem. I don't think CDI testing is possible, just replace and if it works you just tested it.

[mousewheels]

The CDI is one area where a test lamp is not highly valuable. The lamp may not light from the spark trigger coil, or spark exciter coil. Former puts out a low voltage. Latter puts out high voltage (around 300-400v pulse), but little current. Thus an incandescent lamp may not give a reading.

Is there a way to test the CDI, so know it is the ignition coil for power - since that is the last piece before the plug....

Page 14-8 in the service manual gives some CDI info, but not a complete chart for testing...

As motormike points out - There are parametric tests in the Honda Service manual for the CDI. The tests measure resistance at CDI terminals to make a judgement at functionality of the CDI. It's not perfect because it does not actually verify the CDI works, just that it matches a resistance signature of a good CDI. It's worth running the test, but before buying any parts, it never hurts to follow below:

On the practical/fast troubleshooting side, having a box of known good parts, or a spare bike or friend to swap in a CDI or coil goes a long way towards troubleshooting.

Spark exciter coil, coil and CDI all have been failures seen at this site.

[motormike]

I keep forgetting that I have very little business answering posts in the Technical column.
.................................................. ...........I should just ride.............................

[martynkim]

I keep forgetting that I have very little business answering posts in the Technical column.
.................................................. ...........I should just ride.............................

Your input is valued. Opposing diagonsis is a good thing it gives the OP different perspectives. Keep it up!!!

[patthesoundguy]

I agree, motor mike your input is always help full keep it it common

Sent from my Nexus 7 using Tapatalk 2

[brianszubinski]

Gents, as always, your input ROCKS and is appreciated.

I will be bouncing on over to the For Sale section, and purchasing a new CDI and ignition coil. I have been without a ride for 2 weeks (well, one that isn't the public transit system) and in this 90 degree weather I need this baby running ASAP. If any of you would like to sell me the parts, just let me know.

Thanks for all your help. I will report back findings.

MEGA stoked I didn't start replacing wires, and I waited for all of your input first.

Thanks again,

Brian

[swimmingfree]

United States is a big place !!!!! you shooed put up a state and maybe a town as well...
swimmingfree

[MINICooperS]

Realize this is an old thread. . . But . . . . I have had the same issue in the past and the problem turned out to be a partially broken wire feeding the coil . . . with bke running, pushing against the wire harness made it stall . . . FYI