Honda-SOHC

SOHC.co.uk Forums => CB750 => Topic started by: MarkCR750 on June 28, 2019, 05:37:17 PM

Title: Electrical question
Post by: MarkCR750 on June 28, 2019, 05:37:17 PM: Not a Honda but there are some on this forum with good electrical knowledge!, for me electrics = magic!, I’ve fitted small rear indicators on the rear of my Ducati Monster , leaving the standard indicators on the front, now the indicators flash too fast, the small indicators have 5w bulbs and the standard fronts are 21w, if I fit small indicators on the front with 5w bulbs will that fix the problem, or will the flasher unit just not work properly with a total wattage of 10w per side when it’s previously had 42w?,
Title: Re: Electrical question
Post by: SteveD CB500K0 on June 28, 2019, 06:04:33 PM: Assuming the Ducati works like the Hondas, it has a bi-metal strip that heats up and bends when current flows through it.
The bending makes or breaks the contact.
When the contact is broken, the current stops and the heat dies down - and it bends back!

Absolute genius from the 1960s :)

The problem is, if you fit low wattage bulbs (or LEDs), the current won't be high enough to heat the strip in the required time and the indcators either won't work at all or will flash at the wrong rate.
Title: Re: Electrical question
Post by: Moorey on June 28, 2019, 06:05:22 PM: I take it you have fit LEDs. These should cure your problem. You need to increase the load to slow the flash rate.
https://www.ebay.co.uk/itm/4x12V-Motorcycle-Turn-Signal-Indicator-LED-Load-Resistor-Flash-Blinker-Fix-Error/372639494361?epid=1577335561&hash=item56c30b70d9:g:tmIAAOSwcfNcwnXh
Title: Re: Electrical question
Post by: Moorey on June 28, 2019, 06:14:56 PM: Just noticed they are too small they are for 10w not 21w. unless you double them up as it says.
Title: Re: Electrical question
Post by: Moorey on June 28, 2019, 06:18:50 PM: Sorry about that these would be better.
https://www.ebay.co.uk/itm/4PCS-Load-Resistor-Motorcycle-LED-Turn-Signal-Indicator-Flash-Blinker-Fix-Error/401733475400?epid=4023887037&hash=item5d892e5c48:g:ojcAAOSwy6hckgbV
Title: Re: Electrical question
Post by: Erny on June 28, 2019, 07:17:50 PM: I personally prefer other flasher that is independent from load.
Benefit is that you save energy.. Maybe not important for Monster but for old CB it makes some difference in case od LED bulbs 2x few watts instead of 2x21W
Title: Re: Electrical question
Post by: SteveD CB500K0 on June 28, 2019, 07:42:15 PM: I’m with Erny.

Why fit low power bulbs/leds and then throw the power away in a bloody great resistor?

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Title: Re: Electrical question
Post by: MarkCR750 on June 28, 2019, 07:59:57 PM: No not LED’s normal bulbs but they are only 5w not the 21w that the original rear indicators had, at present there are 21w normal bulbs at the front and 5w normal bulbs at the rear.
Title: Re: Electrical question
Post by: Moorey on June 28, 2019, 08:03:05 PM: I would have thought he was doing it for looks, not to save power.
Title: Re: Electrical question
Post by: MarkCR750 on June 28, 2019, 08:26:01 PM: Ha, yes the tail unit on the old monster is a huge great ugly thing combining the number plate holder indicators and mudguard, it had to go!, evidently this is what I need
Title: Re: Electrical question
Post by: Bryanj on June 28, 2019, 10:44:23 PM: The electronic flasher relay is sensing a load drop due to the small bulb so it flashes the other one faster(and idiot bulb) as a warning that you have a bulb gone.
To make it work you need to put the load back up to 42w per side and it will flash ok. An led flasher unit probably wont work properly as the load will be too high with the bulbs you got.
Electics is easy
You cant see it
You cant smell it
But by ell it can hurt if you touch it.

Also NEVER let the smoke out of the wiring loom or you are in big trouble!
Title: Re: Electrical question
Post by: Erny on June 28, 2019, 11:28:03 PM: Quote from: MarkCR750 on June 28, 2019, 07:59:57 PM
No not LED’s normal bulbs but they are only 5w not the 21w that the original rear indicators had, at present there are 21w normal bulbs at the front and 5w normal bulbs at the rear.
Ok... But 5w legacy bulbs I suppose would be barely visible... Not very safe, I suppose. I would go for led in such case
Title: Re: Electrical question
Post by: MarkCR750 on June 29, 2019, 06:59:52 AM: Morning all, apologies I got the wattage wrong, the bulbs are 10w, still not very high I know but they are actually quite bright somehow!, I fitted the Identical ones to my Scrambler and they are clearly visible even in strong sunlight, on my Scrambler I haven’t had to alter anything, being a modern bike it’s got some clever wizardry and strong white mans magic that adjusted to the lower wattage , someone on the Ducati forum fitted the unit above having had the same issue as me and it worked so I’m hopeful, got to be worth a punt for £4, thanks for the replies all much appreciated as always, cheers Mark.
Title: Re: Electrical question
Post by: MarkCR750 on July 06, 2019, 12:17:28 PM: Footnote;
The adjustable flasher just arrived, works well, thought I’d mention it in case anyone else has the same issue with non standard indicators/different bulb wattages, cheers Mark.

Bulbs are more than bright enough at 10w btw.
Title: Re: Electrical question
Post by: Moorey on July 06, 2019, 02:01:08 PM: A good cheap option then. I didn't know you could get adjustable indicator relays. Live and learn. :)
Title: Re: Electrical question
Post by: MarkCR750 on July 06, 2019, 03:46:28 PM: Me too, I’ll probably never need one again but yes a good little unit, the dial control goes from 1 to 150w if that helps anybody.
Title: Re: Electrical question
Post by: SteveD CB500K0 on July 06, 2019, 04:27:04 PM: 150W indicators.

Now there’s a thought

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Title: Re: Electrical question
Post by: MarkCR750 on July 07, 2019, 08:57:35 AM: Could blind drivers at junctions into remaining stationary, could be on to something here!
Title: Re: Electrical question
Post by: SteveD CB500K0 on July 07, 2019, 10:07:33 AM: And if your headlight bulb blows, just switch on the indicators!