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Discussion Starter #1
I have battled for a month with no spark at the front cylinder and have to ask for help. I have an 86 with a sealed MF Yuasa, & iridium plugs. I have tested pickups, pickup connections, I.C. igniter, front ignition coil (not just resistance but with a coil tester), spark plug wires and caps are good per manual specs. All grounds cleaned, all connections cleaned and greased properly. I have read threads about this until my eyes want to jump out of my skull. This started a month ago when I went to start her and she cranked and cranked then the tachometer went dead (although the temp sensor and bulbs work), then she started on the rear cylinder only. At this point it is down to the possible short in the tachometer I have read about. Does anyone have any advice as to what I may be missing? Or how to test for this short in the tachometer? I tried to start it with the tachometer disconnected and got the same result-rear fire only. Thanks in advance to any and all!
 

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Well, sounds like Your CDI is faulty or there is no connection between CDI and coil. Our coils are driven by negative pulse. Please check that You have continuity between coil and CDI, black wire from coil to CDI (CDI = IC ignitor)

EDIT: For short testing, measure that black wire (with Ohm meter) against negative and positive, and in tacho against every wire (for me it does not sound like "internal" short in tacho).
 

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And also check wire from pickup to CDI...

And for notice, if ignition switch ( or starter button) is dirty or broken the bike won't run, not even with one cylinder... Both coils get 12V from same wire from IS and through starter button.
 

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Discussion Starter #5
I will check the black wire tonight, job is interfering with my hobby lol. I did replace the wires from the front pickup coil from the first 4 pin to the CDI as it was not reading properly (good reading from pickup directly but after testing at the other end of the harness was not getting resistance, that's fixed now). Strange thing is I figure the I.C. igniter wouldn't quit for just one cylinder but I am guessing there is something up with the connection to the front coil. Looked over the diagram again last night so now to find the gremlin. I will keep posting as I find more solutions or problems. Thanks guys.
 

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Discussion Starter #7
So if the Ic igniter send a ground pulse to the ignition coil how would one test for this? Resistance check the black wire while cranking the motor? I know I have 12.xx volts at the front ignition red but wouldn't the coil need to ground to send the spark?
 

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So if the Ic igniter send a ground pulse to the ignition coil how would one test for this? Resistance check the black wire while cranking the motor? I know I have 12.xx volts at the front ignition red but wouldn't the coil need to ground to send the spark?
Yes it does, and that black wire gives the ground to coil then when there should be spark. When you measure that 12volts, do you measure it against frame or against that black? If there is continious 12V when you measure between red and black then that black wire could be short to earth... and if there is no voltage (when bike running) then the problem is in CDI or wiring...

If You have fast enough meter (that meter should have option to show "freeze" value = highest measured value... sorry, hard to explain) you can measure voltage between red and black, yout multimeter should show ~12V

I attached a picture from IC Igniter to give idea of basic working principle
 

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yup, when the engine is not running, with ign on, you will read 12v (referenced to frame or battery neg) on BOTH of the coil wires, as the igniter is not providing a ground path for coil.

one thing to remember, while that diagram is a good one to use for the very basic operation of the igniter, there are no relays in it. its all solid state switching. And, it also controls advance of the spark depending on rpm. internally its a lot more complex, but the diagram will give a basic understanding of how it triggers the coils.

some of the better digital meter have a 'peak hold' or 'min hold' feature that would work for checking to see if the igniter is working. you would need to consult the manual for that meter to use it, as they function differently.

*or* if your lucky enough to have an oscilliscope avail, that will show the pulses wonderfully!
 

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Discussion Starter #10
Thanks guys that was all way more useful then the manual I have (old copy not very detailed). My meter is a cheap HF model but I'm sure I can get ahold of a nicer one at work may even have an oscilloscope around here. I'll post any findings this evening.
 

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Discussion Starter #11
I had to wait to get the good testers but in the mean time I tested for dc voltage across the ignition red and black at the front coil with key on and leads unplugged from the terminals, read .4 volts. Individually to a separate ground got 12.75v which is battery voltage. Some is getting across and also tested for continuity from black wire at the lead and at the harness unplugged from i.c. igniter and numbers are small but not infinite so either there is a short or it is because of the ground at the tach. more testing and results to come but weather here isn't so great so it will be this weekend probably.
 

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Discussion Starter #12
Victory!!! After all that work and more tests I hit eBay and scored an Ignitor for 52.00 shipped. Plugged it in and she is back to normal. Thanks guys for the suggestions.
 
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