Rev Counter Illumination

[nice2day]

Hi All. I am reluctant to voice this tip as maybe everyone already knows? It's regarding the fact that the rev counter light on standard bikes only illuminates when the headlamp is switched on. Presumably this is done to reduce battery drainage if the parking lamp was left on whilst parked up, saving about 3-4 watts. It is a 2 minute fix to change this but maybe you all know this or don't want to change the set up? Personally, I like both rev counter and speedo illuminated whatever lights are switched on
If anyone wants to know how to......

Les

[Puffs]

Well OK, but maybe you can take it as a hint to switch your lights on?

[nice2day]

I think its a quirky arrangement and serves no purpose in the UK.
Here is how you do it:

Get a thick towel and drape it over your front mudguard. This is to protect the mudguard if you drop the screwdriver when removing the headlamp unit to let it hang down.

Right...
1) Get a torch and look at that mess of wires. Then find the bunch of wires that come into the headlamp shell from the rev counter (hole on the right as you view it)

2) Single out the white and black one which is the easiest one to see fortunately.

3) Trace it back to the left connector (as you view it) It will be connected usually to the pins near the centre. Carefully pull this off with long nose pliers.

4) Now look at the right connector block and find the white and black wire which will be connected to the pins right at the front. The front pin connector on the block is a 4x way so there should be one spare position on it, there will also be 2x grey wires connected to this position.

5) Now simply plug in the wire you have just removed and fit it to the position as described so that there are now 2x white and black wires and 2x grey wires all connected.

6) Switch on the ignition switch to the parking lamp illuminates and then smile as your rev counter is illuminated like its partner the speedo! (we'll assume the rev counter lights DID work before when the headlights were switched on!)

7) Refit the headlamp unit, tighten up the screw. Remove the towel and take it back to the bathroom and don't tell your wife where it has been.

Re-test the new set up and feel joyous that you have modernised your bike and can't wait to test it out when riding after dark

Les

PS..For the nervous or safety conscious person perhaps you can remove one battery lead but all the wires are fused anyway and the ignition will be off so not much chance of shorting anything.

[Blurredman]

Well I never!

I have both the 250 and the 251 wiring diagrammes:

ftp://blurredmanswebsite.ddns.net/Vehic ... TZ_250.jpg

ftp://blurredmanswebsite.ddns.net/Vehic ... TZ_251.jpg



The 250 has neither clocks illuminated on the pilot lamp. But I knew this and it never bothered me to the extent that I wanted to change it- I just thought c'est la vie.


When re-wiring my 251 back to standard when I first got it, I wired it up according to the (revised) 251 wiring diagramme above. To my knowledge I remember thinking "well it works on the headlamp but not on the pilot even though the revised wiring diagramme should allow this"... Maybe I was inadvertently looking at the tacho all along... Very interesting!


And yes- as you say.. it's simple enough now to move just the one wire... Will do some experiments and see for myself that the speedo light only comes on.


Personally, I never notice the backlights illuminated unless it's extremely dark- with the pilot lamps on it is normally the situation where it is just on the cusp of dawn or dust (or foggy) which - I can see the clocks perfectly fine anyway.

[Puffs]

I *think* the backlight on my rev counter works, with lights on, but lights are the only thing that works...

No cable.jpg (10.58 KiB) Viewed 2274 times

[nice2day]

Here is a quick diagram to show what I mean:

Les

[nice2day]

Looks like your rev counter drive has got "Brewers Droop" Puffs. A term us Brits use for lack of performance in the lower body department

Les

[DAVID THOMPSON]

if your headlamp is on on a car your dash lamp on the speedometer is on
and your tail and brake is on that circuit also they all use the same fuse on most i have worked on
if you do not have a speedo lamp on you may have a bad fuse on your tail lamp and stop bulb

get a drawing for you bike and take a close look at how the brake and tail lamp are wired

and every time you ride check your tail and brake lamp are working

getting hit in the ass is no fun

dave

[Blurredman]

As Puffs, I also broke my tacho cable (or it broke itself I suppose- but not bad if it was an original!)... Still on the lookout for an 80mm long replacement... Anyone....... ? Not even the usual hoarders in the MZ club have one it seems..


Anyway.. I checked mine when I got the bike in my garage last night (dark in there!), and neither light with the pilot lamp. They both only light when the Main lamp is on..

I will be looking into this- it's quite interesting (I think). Maybe I wired it not according to the diagramme at all. Who knows.. I do recall that my '87 250 does have a later (single set of wires instead of two sets of wires) for the left switch gear which took my head some getting around to wire it in to the older wiring diagramme.. But I do think the supplied diagrammes are the easiest and best diagrammes I have ever had the pleasure of working with. They're so great!


David makes a very interesting point.. My Honda CX500 is wired such that if both bulbs of the tail lamp are blown (or not working etc) then the pilot lights on the clocks do not light up. This is an indicator, so long as you know what it means

[Puffs]

While I did plug the drive connection, to prevent oil coming out, I turned it 120° ("Brewers Droop") to prevent water to enter (rain + wind pressure). You also see it on the MZ's used on the track, as I saw later on pics & vids. I don't think I'm the only one who thinks a rev counter is slightly pointless on a bike like this.
Anyway, the cable was damaged 20+ years ago, took it off & did most of the miles without. Then when I cleaned the bike up, I 'fixed' the kink in the cable, and drove a few years with a rev counter. And then the cable broke, a year or so back. Once I almost had a new one.

Again: if you want that backlight, you can also just switch your headlight on. That makes for a safer ride & is the default for me (+ the law).

[dave47]

If you are likely to put the ignition switch in the "parking" position, either intentionally or accidentally, it would be better to power both clocks from the headlight circuit, rather than the pilot/parking light circuit. The four 2 watt instrument bulbs use nearly as much power as the parking lights themselves.

[nice2day]

Thank you Dave for the warning but I have no intention EVER of leaving my parking light on for hours on end without the engine running. If I did leave the lights on accidently and the battery went flat I would call myself an idiot and make certain I didn't do it again. When a bike has a 200W generator and I am riding around on it I think the extra 3-4 watts is going to be of any concern to me of draining the battery. However there may be some people who fear that the modification will exhaust their battery, so I say to them...just leave your wiring untouched...simple.

Les