another intermitent spark moby ?

John Jorgensen /

Okay, so its a 77 moby 50v with the following done electrically. Ran great yesterday, died today, no consistent spark anymore.

- Disconnected kill switch

- Reset timing

- cleaned points

- Already has an external condensor wired up

I tried another stator plate and points as well, but didnt have the timing dialed in and it started right up but ran like crap. I didnt know if the plate was any good so just a rough setting of the timing to test. It ran, so I retime it properly, no more spark. Check parts with voltmeter, lots of shorting/grounding out, so go back to my old stator plate.

THe old plate checks out good with multimeter. Try starting the bike and all the lights come on. No spark, no start... Check for power at the grey lead to the coil, and its got great voltage. Check for power from the coil great voltage. check the spark plug wire, still good. Test the boot, still getting power. I've tried a brand new plug, my old plug, etc. No go.

Suggestions?

Re: another intermitent spark moby ?

Ground strap good? Brake light socket/ground clean?

Re: another intermitent spark moby ?

John Jorgensen /

ground straps good, brake lights working, so i didmt think id have to check, but ill go through it.

Re: another intermitent spark moby ?

Is it a two coil or three coil 6/12 volt genny? If it is a two coil then the "12 volt" terminal needs to run through an accessory to the common or just be routed to the common. Reroute your bonding strap from the external coil to one of the intake studs for better contact.

Could also be sketchy contact between the external coil and the plug. Check they are goodly tight. Do not put a resistor plug in her if you have the original anti-parasite plug cap.

Re: another intermitent spark moby ?

John Jorgensen /

It's a two coil in there now, I tried Thea three coil bit that's the one that's shorted out. I have already replaced the bonding strap with a new wire thats run from the coil to the intake studs. I have two coils, one with the stock plug cap, another with Ngk. I didn't run a resistor plug in either.

Gonna try a new condenser today, maybe it went bad?

Re: another intermitent spark moby ?

John Jorgensen /

new condensor, still no go. very frustrating. I may have to hardwire it... I was getting some light shock on my hand when checking the hi tension coil wire, but it wont translate into any sparking.

Re: another intermitent spark moby ?

Dress the points with a points file or a metal fingernail file and flush with either brake cleaner or alcohol.

Index the points at widest open to 0,35mm then turn the crank clockwise until the piston is at 1,5mm BTDC and set the cam so the points are only just opening.

If you have the 3 coil 6/12 volt genny then check that the common end of the coil is well soldered to the iron core, sometimes it is not such a goodly solder there which will give you sketchy spark.

If the external coil is chalky looking then change out the coil for a new one.

Re: another intermitent spark moby ?

John Jorgensen /

if running a continuity test on the exciter coil, should the lead coming off of it (the wire from the coil under the magneto, going to the points), have continuity to ground? or is this exciter coil fried?

Re: another intermitent spark moby ?

The exciter coil should have 1 or 2 ohm, you have to disconnect the coil from the points and condenser before testing.

« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account