Ignition Coil Voltage

[dalorian]

Well, after doing Evguru's test I was a little disappointed that I could not find anything obvious but then I checked the plug wires just to be sure and they are both zero ohms and seem very solid. Blue wires also seem to be very well grounded under the tank. I will check the AC voltage coming out of the green ignition wire while just normal cranking . What should it be while just normally cranking with the spark plugs out ? I have been just cranking it with an external battery with no plugs in it and I get 35 volts AC but It might tell me something if I just crank it normally . If it is so low that there may not be enough voltage to make a spark so if there is a normal voltage while just kick starting what would it be ? That will tell me something. Thanks , all, for your help.

[72degrees]

I'm pretty sure I get more like 50V AC at kickstand speed (well peaking at that). Given the reasonable resistance for the winding, perhaps the rotor magnetism is down, but I would expect at least a weak spark then.

[dalorian]

Well, now , I am getting about 45 VAC peaking now and a spark. I have learned not to trust the electric starter . I don't know but maybe the battery was just not strong enough voltage wise to get it cranking fast enough even though I did not have the plugs in it but when I kick start it , there is a faster speed and in turn a spark . I am cleaning the gas tank right now to put some gas in it but I probably have to go through the carbs first. Thanks

[72degrees]

Still sounds as if the ignition may be below par. They will usually fire up ok on the e-start so long as that is gripping and turning the motor over properly. Progress though!

[MickeyMoto]

My old 500 was the same. Starter made clonking noises and would only start warm. Changed the battery for a Yuasa and bingo! Needs a good battery to spin up the engine. Shows how good a kick start is.

[dalorian]

I'm stumped , I lost spark altogether when I took the flywheel off and checked out the coil . All I did was to clean the rust off from the ignition coil so that it would not provide resistance . I reinstalled the flywheel and held the spark plug and cranked like mad but couldn't even feel a tingle but I'm getting 52 volts AC out of the coil directly . I checked everything out again with the light bulb on the boxes again but all checked good. I have never been stumped like this before on a motorcycle .

[dalorian]

Okay , just now I hooked everything up again after checking the boxes with the light and also checking the pickups with the light . It turns on and stays on just like the test on the You tube video . Now just for the heck of it , I took the spark plugs out and held the spark plug electrode and cranked it as fast as I could , i got 53 volts AC as a peak on my meter but could only feel when the spark plugs were firing. I could tell each time the plug would fire but nothing really hurt me. If anyone could just hold theirs like this and let me know how it feels it would really benefit me . Just kidding, but that's where I'm at.

[adrianb]

Did you find out what the problem was? I've got a similar issue myself after a re-build.

[dalorian]

Well, I am getting back into this now and I have no spark but I accidently had the green wire in my hand while cranking and it shocked me quite briskly but the spark plug did not , even while holding the electrode in my hand and grounding myself to the frame I get just a tiny click but not enough to even shock me. It is far more powerful directly from the ignition coil . Does anyone have a voltage reading from the pickup coil ? Mine is less than a half of volt , maybe .392 volt. Now I am thinking that the ignition voltage is enough since it does shock me but the secondary spark coming out of both boxes do not even shock me while holding it. The pickups are the only things that Soren say is quite a problem and cause no spark in both plugs.

[dalorian]

Well, I am getting back into this now and I have no spark but I accidently had the green wire in my hand while cranking and it shocked me quite briskly but the spark plug did not , even while holding the electrode in my hand and grounding myself to the frame I get just a tiny click but not enough to even shock me. It is far more powerful directly from the ignition coil . Does anyone have a voltage reading from the pickup coil ? Mine is less than a half of volt , maybe .392 volt. Now I am thinking that the ignition voltage is enough since it does shock me but the secondary spark coming out of both boxes do not even shock me while holding it. The pickups are the only things that Soren say is quite a problem and cause no spark in both plugs.

[dalorian]

Has anyone ever measured the AC voltage coming out of the green wire from the ignition coil just foot cranking ? Must have a multi meter that holds of coarse but I have heard numerous times that the voltage idling should be 90 volts but what if you cannot even get it running ? I get about 47 volts AC intermittently . I sure would like to know if anyone has done this test ? I just need to rule out the ignition coil as the problem .

[Ming]

I've just measured the output on mine for you. It's from a 250C2, but the ignition system is similar.
Source coil resistance is 230 ohms (this is only a rough guide to it's health).
Kick-over voltage (with the coil disconnected from the transducers) is about 40Vac.
Voltage to transducers on a running engine is around 60Vac at tick-over, rising to about 100Vac on higher revs.
All this is with a direct feed from source to transducers, though, i.e. cutting out the rest of the wiring loom, ignition switch, etc. Also with spark-plugs in place (well, they would be for the engine to run, eh?)
Good luck.