Motorcycle flasher mystery.

[roadrash]

usually get help on here for computers and monitors etc but I thought you guys are the best I can think off to help me solve a real mystery.
I have a Honda NT650V bike and recently fitted a towbar to tug a little trailer sometimes.
Everything was good until I connected up the trailer socket.
The problem is whenever I use the direction indicators/flashers it causes a misfire as soon as I cancel the flashers the misfire stops. The bike without the trailer lights attached is fine.
.So far Ive tried the following:
1) I replaced the battery for a higher A/h original was only 9AH which is known to be marginal for this bike but now its 14 ah.
2) Tried changing the flasher unit for another heavier duty type.
3) mas only one earth from battery to engine so I added another from battery to frame as well.
When wiring the trailer socket I just took the connection from the rear lights on the bike as ive done before and all connections were soldered (not crimped or scotch-locked into)
Turning off all other items like headlamp etc has no effect. Battery voltage doesn't drop when all indicators are used.
I was wondering if maybe the extra load on the flashers are spiking the circuit somehow affecting the bike CDI ignition.
I had a idea that maybe if I were to put a diode in cicuit for each of the trailers indiators it might cure it but wouldnt know which kind of diode would be best.
The bike on its own has 4x indicators (2 each side) 12v 21w bulbs & a little 4w warning light. The trailer has 2x 12V 21W bulbs.
You guys are great and helped a lot in the past and I am sure you will know how to solve this.
Here is a schematic..

[stj]

your probably drawing too much power without any smoothing caps
BUT given your limited power - try fitting led bulbs on the trailer.
not the ones with a balast resistor to fool lamp sensing either, just simple chinese led bulbs

[petehall347]

check fuse voltages flashers on .
i suspect the ignition switch or wiring ..
the ignition circuit is pulling some of its power through other stuff like flasher bulbs instead of where it should .
i have had cars that would stay running with key off the engine would run in time with the flashers .to do this i had the wipers on and hazard lamps at the same time .this allowed a feed to the ignition circuit as well as the hazards .

[roadrash]

Originally Posted by stj

your probably drawing too much power without any smoothing caps
BUT given your limited power - try fitting led bulbs on the trailer.
not the ones with a balast resistor to fool lamp sensing either, just simple chinese led bulbs

Great idea STJ why didn't I think of that (light emitting DIODES). Hahaha.
Cheers will let you know if it works

[roadrash]

Just connected up a couple of old after market led motorcycle indicators in place of the normal 12v 21w incandescent bulbs and it works!
Just ordered a couple of clear Led reverse light bulbs off ebay so hopefully that should sort it.
Just out of interest if I has used a inline diode with a incadesessant bulb would that have worked too?
Cheers stj

[eccerr0r]

No
The aspect that it's a diode is inconsequential, the fact that it's an LED that's 4 to 10x more efficient at generating light is the key factor.

Do not go get a pair of 21W super bright LED bulbs, you'll be back at square 1.

[stj]

it may not be as bad for reversing lamps, the draw is constant.
indicators and brakes are risky though - not times you want a stall!

[redwire]

Incandescent lamps are an inductive load actually, the filament is a double wound coil. So there is a voltage spike when they switch off as well as inrush current of around 5-10x their normal current when they turn on.
Car makers have caps across the flasher contacts like 0.02uF in order to suppress the voltage spike noise. Sounds like the inrush current of the extra lamps (going on) was causing a glitch in 12V power, or voltage spike (going off) and the misfires.
The Ignition Module is a bit weird having connections to the Clutch/Kickstand/Neutral switches which might be picking up noise. If the misfires were when driving. I think the switches retards ignition timing maybe.

But LED lamps are the way to go, as long as they have a decent viewing angle.

[roadrash]

Very interesting that. Just had the very problem of viewing angle with first set of bulbs that turned up.
They made indicators flash a bit faster and the indicaotor bulbs in these light units fit on the side so from the rear you are seeing the light coming from the side of the bulb and these led bulbs dont emit any light much from side on.

[roadrash]

Originally Posted by redwire

Car makers have caps across the flasher contacts like 0.02uF in order to suppress the voltage spike noise.

If I put .0.2uf caps between earth and each of the extra bulbs, would that work too?
The side stand and clutch/ neutral switch are safety features. In 1979 I had a serious life changing crash when I left the side stand down after filling with petrol after work. Then rose off to 1st left corner and unable to bank bike to go round corner and hit car coming other way. Lucky to be alive and a year in hospital. So glad of these features now.

[roadrash]

Just to let everyone know I used led bulbs instead and it cured the misfire when the indicators were used.
I also found slightly tarnished contacts on all the fuses and found there was a diode in the fuse box which after I cleaned its contacts also cured a slight single occasional misfire when at low revs and under load like when slowly powering out of a slow turn (very annoying sometimes).