weak/erratic spark By kingcricket (Read 5,285 times)

[kingcricket]

Its an ngk plug

[Bashan]

I found this chart on the possible causes of a bad spark:

Did anybody notice on that video how the spark got regular when the plug was arcing down to the valve cover? Actually, the intensity of the spark looks OK but it is irregular until the plug lifts off of the cover. That might support the theory of needing a wider gap or maybe a bad boot which makes a better contact when there's no weight on the plug. Other than that, I'm stumped. If it was me I'd pull all of that wiring and scratch wire the whole spark genesis mechanism. Rich

[kingcricket]

Thats what i did everything is wired so it should work but it doesnt still same voltage drop from wire heading into the ignition coil, which is a new one with a good tight boot. I did gap the plug more which made no difference. Should the magneto have a ground through it, because i get no continuity with it and the case or anything. Even the crankshaft doesnt have continuity with the case. Just thought that was odd.

[Alleyoop]

That could be it, Ground the Stator.
Alleyoop

[kingcricket]

See thats the thing the stator is grounding but the shaft in the middle isnt, so the magneto doesnt have ground in it. Idk with the magneto off theres continuity from the frame to the staor monunts and casing behind but nothing to the crankshaft, unless it not supposed to idk.

[Alleyoop]

Well the crankshaft rides on bearings which are in the casing inside so if the motor has a good ground then the crankshaft you should get continuity.
Alleyoop

[kingcricket]

Yea you would think but it doesnt

[Alleyoop]

And you have a good ground wire from the motor to the frame I assume.
Alleyoop

[Bashan]

The magneto coil grounds to the stator frame which grounds to the case through it's mount. However! The Magneto coil ground is a higher resistance than the no resistance grounds on the white and yellow wires. The magneto coil ground has resistance built in, enough that it is over the 60 ohm multimeter limit for a continuity tone. Therefore it appears there is no continuity but there IS a connection, it meters at about 550 ohms.

[Alleyoop]

SO WHAT DOES THAT ALL MEAN "Carnac the Magnificent"

[Bashan]

I just went down to my shop and tested a GY6. I had continuity from crank to case, from crank to black solenoid terminal, and continuity from crank to frame. This makes sense because you have metal to metal at the very least crank/connecting rod/piston/rings/cylinder/case. And as Alley said, the journals. Having said that the crank isn't really involved in the circuitry of the stator or anything else. The grounding occurs through the stator frame and case. Does your stator pigtail have a green ground wire? Some of them don't. If you do.... do you get continuity from the green wire stator side to case? Do you have continuity from the white wire unplugged stator side to case? Do you have continuity from the yellow wire unplugged from stator side to case? Do you have continuity from white to yellow both unplugged stator side? How about green bike side to frame? Rich

[Bashan]

It means if he will test the ohms from the magneto coil ground to case or stator frame and he gets 550 ohms there's nothing wrong with the magneto ground. That has to do with the capacitors releasing their charge. Depending on the config a little resistance is needed. Then we can take the magneto coil off of the table as a potential problem.

Next, the Great Stinky Carnac wants to see if the stator's grounds are adequate by continuity testing. I'm thinking the circuit is just not getting back to the stator. The crank has nothing to do with this, all it does is spin the flywheel. Rich

[kingcricket]

So after all the testing and troubleshooting and prolonged agony i figured screw it and put the plug in and put two stroke ges in i know bad but thats all i had and was at wits end but kicked the hell out of it and fired right up. O thank god now i gotta put the old wiring back in and hook the lights up and hope it still works. And the power was 28 at ignition coil

[Bashan]

I'm going to go kill myself now, goodbye everybody, it's been great. Carnac

[Alleyoop]

So 10 year old gas was in it(HAHAHHA) great I think I will join you rich.
Alleyoop