weird electrical issue?

[nokturnal]

I have just got my bike together, converting it from a track bike (all "legal" wires were just cut, headlight, signals, etc.
). I am pretty sure I wired everything up correctly. Multimeter and wiring diagram in hand...

Everything seems to work as it should when the bike is just on the battery. When I rev the bike up when running though the headlight dims and the signals start to glow.

The same thing happens with a battery from another bike, and my brand new lithium, as well as 3 regulators (maybe all bad??).

Ideas? I need this thing ready to go by Thursday...

[earthman]

Stating which bike you are talking about may help with replies in the first place?

If the headlight and turn signals work fine until you fire up the engine, my guess is that the fault must be charging circuit related.

[nokturnal]

It’s an 81 LC 350

Thanks for your reply.

[muttsnuts]

check your stator and also engine earthing, check all of your earth (ground) connections (black wires) and make sure they are all clean and making good contact, check you have the correct reg/rec fitted as well, is it a new loom or an old one, if its an old one then chances are you will need to unwrap it, find all of the earths that are paired together and clean/remake all of the connections as they corrode really badly

[nokturnal]

All 3 were 4L0 regulators. All old... will test them.

Old loom, so will check grounds. Would this not also cause the problem to happen when the bike is not running?

Will test the stator output. Hope this is not the issue...

[nokturnal]

also... if the front signals glow and headlight dims, but the rear signals don't, could it be isolated to the headlight bucket wiring? will need to check this as well... only really looked at the front.

[yamark]

First thing to check, with a fully charged battery and lights/ indicators(signals) switched off.

Use a volt meter to check your battery voltage.

Then start the bike and measure again. Next rev the bike to around 5,000rpm.

Fully charged battery should read 12-12.5 volts

Bike on idle 12.5-13 volts

Bike at 5,000rpm 13.5-14.5 volts

If when you rev the bike and the voltage doesn't rise, you have a problem with the alternator or reg/rectifier.

If the values check out, your battery, alternator and regulator/rectifier are OK

You have a wiring fault or earth fault.

It points to an earth fault if other circuits light up when they shouldn't, as the headlight could be trying to earth through the indicators(that's why they glow).

You can run a wire from the headlight earth straight to the battery negative and see if the fault disappears.

But as Mutts says, check all earths, electricity finds very strange paths to complete a circuit.

Hope that helps, Mark  

[bare]

Yama... for Years fitted Piss Poor/inadequate Grounding circuits to their products.
Only Yama San knows the why of this tho.
Fair chance there is unexpected leakages as result.
Most any Yama Loom features melted ground (black) wires as result of this genius work.

Fit a few 'extra' ground paths ?
ie: from Battery Negative directly to Frame/ground also from headlight loom mess to frame and from engine to frame.
Might even help.. sure as hell won't hurt anything .

[nokturnal]

Prelim results pointing to bad ground on the headlight (good one, Mark)

Problem went away when headlight was unplugged. Stayed away when a new temp ground was run from the headlight.


After my trip this weekend, I'll dig into the main harness and work on the joints.


Thanks guys

[yamark]

Aug 14, 2018 3:25:30 GMT 1 nokturnal said:

Prelim results pointing to bad ground on the headlight (good one, Mark)

Problem went away when headlight was unplugged. Stayed away when a new temp ground was run from the headlight.


After my trip this weekend, I'll dig into the main harness and work on the joints.


Thanks guys

Glad your sorted

[rich]

I'm wondering if you have a brown wire switched? It's easy to get the light brown for the front brake light switch swapped with the darker brown for the front indicators?

[nokturnal]

Defo have the dark brown wire to the signal.

The signals now work properly. Headlight doesn't dim. Both have their own grounds now...

The dash however is all over... the signal idiot lights glow when the bike is revved, the temp gauge is off the chart, and when the signals are put on the high beam and signal idiot lights blink blink with no rhyme or reason like a bloody christmas tree...

[125lc1dt]

Interesting point on running extra earths. Does the wire have to be a certain diameter. I’ve heard powdercoating can make connections suspect.