Topic: Timing Jumping around on cyl 3 with timing light, whats going on?

[73CB500K2]

While checking the timing on my 73 CB500K2 using my inductive time light I get erratic jumping around of the timing mark and the strobe seems irregular on cylinder no. 3 as opposed to all the other cylinders which have a steady strobe and rock solid timing mark.

I need your thoughts on what could be causing this.

[cmonSTART]

Just to be clear, stock points and coils?

[phil71]

it's likely just the pickup of the timing light having intermittent tracking.  2&3 are the same coil. If the bike's running well, ignore it, use #2 wire

[BobbyR]

That can be the sign of a faulty wire or a bad plug.

[73CB500K2]

Just to be clear, stock points and coils?

Yes stock coils and new points however before I replaced the points the same condition existed.

Bad plug wire? I tend to agree. I just trimmed all the plug wires and installed new plug caps with dielectric grease.

I thought about the time light receiving some kind of interference from something on plug wire 3 but its solid when attached to plug wire 2.

Still got me baffled 

[phil71]

it could be solar flares too.

[phil71]

you don't mention.. is the bike running fine?

[73CB500K2]

you don't mention.. is the bike running fine?

Yeah its running good idle at 950 rpm smoothly and runs down the road strong I was just fooling around and double checking everything regarding the timing since I recently installed the new points.

[73CB500K2]

That can be the sign of a faulty wire or a bad plug.

A bad plug? That's  a cheap test. I will have to pick up some new ones and give that a try. New plugs cant hurt.

I was thinking the inductive timing light picks up the current coming down the plug wire and that is what triggers the strobe right? Does the spark plug have something to do with the inductive timing light strobe light?

[lucky]

That can be the sign of a faulty wire or a bad plug.

A bad plug? That's  a cheap test. I will have to pick up some new ones and give that a try. New plugs cant hurt.

I was thinking the inductive timing light picks up the current coming down the plug wire and that is what triggers the strobe right? Does the spark plug have something to do with the inductive timing light strobe light?

Electricity does not go down a wire. A load can be placed on a wire.
the timing light is inductive. The spark plug has nothing to do with it.
I know what you are thinking. Does the timing light ROB the spark from the spark plug.

[phil71]

these wires have a 2nd sheath that makes the inductive pickup on timing lights track poorly. Move it around, you'll see what I mean.
If the bike runs good, it's good. Put down your wrenches and ride.

[BobbyR]

A plug that does not or fires erratically will cause an erratic light. The induction coil can also pick up interference from the wires around it also. If it is on three but close enough to four it can sense that also.

Move the wire as close to the plug boot as you can away from other wires. Oh Yeah keep it away from the exhaust headers.

[bollingball]

Pull the plug and ground it on the engine and see if the spark is doing the same thing as the light if not than it is just a poor reading on the light. Try flipping the clamp over.

Ken

[somesuch]

A plug that does not or fires erratically will cause an erratic light.
...

I have seen this with old/fouled plugs

[phil71]

He says the bike runs great. Why do you want to make work for this poor guy?

[73CB500K2]

Thanks to everyone who responded to this topic.

I did flip the timing light pickup and moved it as close to the spark plug as possible and that solved the problem. I agree that it was interference with the other plug wires or to close to them, which caused the problem.

So this topic is solved thanks again to all....