Electrical spark arcing from Carburator to Frame

[Terrible1]

Im working on a 81 xs650, all stock charging system/ignition. I have a relocated fuse box inside a fake oil tank under the seat. When going to adjust the Carb Sync screw in the middle, I am noticing a spark/arcing that will jump from the screw driver to the frame when I am on the carb sync screw. I can also make it jump from the engine to the frame in the same fashion. If I touch the screw driver to the Engine Case vent tubes to the frame it does the same thing.

I have checked that my coils are not to close to the frame, and that my spark plug wires/boots are not cracked. I replaced the spark plug boot end, and the coil end when doing a refresh on the bike a week or so before. I am not getting any arcing from the spark pug wires to the case/engine at all either. I have checked the condenser wires that are under the tank/frame and covered those in some heat shrink to make sure nothing is arcing or shorting out. I've tried to get the engine cases around the top to arc to the down tube on the frame, and nothing, and the same with the fork tubes to the engine case/etc.

The spark is an orange spark, and almost is similar to something shorting out. I believe this is only happening when the bike is running, so I would think its a charging issue that is causing the arc.

Anyone have any ideas what it may be?

I'm in the middle of the build, so I do not know if this has been an issue before. The bike does run, but I am waiting on other parts to finish up the carbs before I can do a full tune up.

 

[mrriggs]

Obviously, since the fuse box is in the fake oil tank, the orange you see is the fake-oil leaking out through the electrical system.

Seriously though... It sounds like you have a bad ground connection. The big wire from the negative battery terminal needs to run directly to the engine. You also need a wire run from the engine to the frame, don't rely on the mounts. All the connection points need to be clean and tight. Remove any paint or powder coat so there is metal-to-metal contact.

 

[gggGary]

+1 look into ground issues.
Check the fork and handlebar grounds also. Carbs are rubber mounted but ground to the handle bars via the throttle cable. Engine grounds to bars via the clutch cable.

 

[Terrible1]

+1 look into ground issues.
Check the fork and handlebar grounds also. Carbs are rubber mounted but ground to the handle bars via the throttle cable. Engine grounds to bars via the clutch cable.

This is key in my eyes. I was thinking all day about this and realized the carbs hang on the boots. No good for grounding. I will jumper a hard ground to the carbs and report back.

Obviously, since the fuse box is in the fake oil tank, the orange you see is the fake-oil leaking out through the electrical system.

Seriously though... It sounds like you have a bad ground connection. The big wire from the negative battery terminal needs to run directly to the engine. You also need a wire run from the engine to the frame, don't rely on the mounts. All the connection points need to be clean and tight. Remove any paint or powder coat so there is metal-to-metal contact.

An all new ground was installed by me daisy chained from battery to frame mount to engine case. I will double check them and report back.

Thanks guys.

 

[gggGary]

Please ground the bars and fork to the frame, a missing fork ground can eat your steering bearings. Missing bar grounds has had many a custom builder chasing their tail.

 

[TwoManyXS1Bs]

Obviously, since the fuse box is in the fake oil tank, the orange you see is the fake-oil leaking out through the electrical system.

Good one! I fell outa my chair! Fond memories of 'Laurel and Hardy'...

 

[gggGary]

The british guys know how to fix this stuff. You let the smoke out of the wiring harness, it must be replaced....

 

[DIRTY DOG]

now thats funny

 

[Terrible1]

Update: I reinstalled all new grounds chained from battery to frame, to engine mount, to engine case. I then installed a jumper from the valve cover to the carburetor diaphragm, followed by a jumper from the other valve cover to the headlight bracket, then to the handle bars. I fired the engine up and put the screw driver blade down near the carb and frame. The spark is still there. I looked into making the spark happen again and found that it is only jumping from the engine crank case breather to the frame.

I ohm'd out all the grounds and nothing was over 20ohms from the battery forward.

I'm somewhat stumped. The spark/arc doesn't seem to follow a coil firing.. When trying to get the arc to jump from the engine case else ware to the frame nothing happens. Any one want to throw some ideas at me!? TIA

 

[TwoManyXS1Bs]

Im working on a 81 xs650, all stock charging system/ignition.

...I have checked the condenser wires that are under the tank/frame...

Condenser? That raises a flag.

...I would think its a charging issue that is causing the arc.

Could check for grounding of stator, rotor, brushes, 3-phase lines...

 

[DIRTY DOG]

20 ohms is a little high usually any thing ove 2 ohm is bad for a ground.one good ground from the eng. case to the battery neg.should be good for the eng. and one to the frame.
is it a one time spark or does it keep repetting it self like a spark plug.

 

[Terrible1]

Condenser? That raises a flag.



Could check for grounding of stator, rotor, brushes, 3-phase lines...

Sorry, in my late night posting I left out some info. I decoded the engine and it turns out I have a 72/73 tx650 in the 81 frame. This was not known till last night.

20 ohms is a little high usually any thing ove 2 ohm is bad for a ground.one good ground from the eng. case to the battery neg.should be good for the eng. and one to the frame.
is it a one time spark or does it keep repetting it self like a spark plug.

I made sure that All my connections are clean of oil/paint/bad connectors. I will revisit all of them and report back. It is a steady arc, not a pulsing like a coil firing.

Thanks for the help guys.