Electronic tachos

As subject.

Do they have some sort of 'damping' mechanism in them?

I ask as the NS is now nearly half way through its running in period and I
noticed that, once the bike has been running for a while, the tacho goes a
bit wibbly-vague...

The only reason I can think of is that it has an oil (or similar) based
damping mechanism and that, when the oil (or similar) gets warm, the needle
isn't 'damped' into position as well as it should be......

Is thi the case or is there another reason (bearing in mind it's fine until
the tacho has been operating for a number of miles and the needle has done a
fair bit of sweeping round the clock etc...)

TIA

Dave

 

Eee.

Leck.

Tron.

Ick.

hth

--
| ___ Salad Dodger
|/ \
_/_____\_ GL1500SEV/CBR1100XXX/KH500A8/TS250C
|_\_____/_| ..74309../..18302.../..3184./.19406
(>|_|_|<) TPPFATUICG#7 DIAABTCOD#9 YTC#4 PM#5
|__|_|__| BOTAFOT #70 BOTAFOF #09 two#11 WG*
\ |^| / IbW#0 & KotIbW# BotTOS#6 GP#4
\|^|/ ANORAK#17 IbB#4
'^' RBR Landmarks: 12 Pts: 220 Miles: 914

 

Well it beats my water cooled FJ

Read the subject line - YTC )

 

Bear emerged from their own little world to say

Evidently.

First we have water cooled FJs, now cable operated electronic tachos. Is
it the YTCery season?

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, wessie

Well, 'ow else do the poor little electrons get all the way up to the
tacho then? Bless 'em.

--
Wicked Uncle Nigel - Manufacturer of the "Champion-105" range of rearsets
and Ducati Race Engineer.

WS* GHPOTHUF#24 APOSTLE#14 DLC#1 COFF#20 BOTAFOT#150 HYPO#0(KoTL) IbW#41
ZZR1100, Enfield 500 Curry House Racer "The Basmati Rice Burner",
Honda GL1000K2 (On its hols) Kawasaki ZN1300 Voyager "Oh, Oh, It's so big"

 

That would appear to be the best option ATM.

May I refer Sir to SD's more detailed description......

Dave

 

Wicked Uncle Nigel emerged from their own little world to say

They loom.

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, Bear

Good night Bear.

I said GOOD NIGHT BEAR!

--
Wicked Uncle Nigel - Manufacturer of the "Champion-105" range of rearsets
and Ducati Race Engineer.

WS* GHPOTHUF#24 APOSTLE#14 DLC#1 COFF#20 BOTAFOT#150 HYPO#0(KoTL) IbW#41
ZZR1100, Enfield 500 Curry House Racer "The Basmati Rice Burner",
Honda GL1000K2 (On its hols) Kawasaki ZN1300 Voyager "Oh, Oh, It's so big"

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, wessie

Well I never! So *that's* why....

Every day is, without doubt, a school day.

If only we could find a way to harness their power.

--
Wicked Uncle Nigel - Manufacturer of the "Champion-105" range of rearsets
and Ducati Race Engineer.

WS* GHPOTHUF#24 APOSTLE#14 DLC#1 COFF#20 BOTAFOT#150 HYPO#0(KoTL) IbW#41
ZZR1100, Enfield 500 Curry House Racer "The Basmati Rice Burner",
Honda GL1000K2 (On its hols) Kawasaki ZN1300 Voyager "Oh, Oh, It's so big"

 

No, not you. Rog had a moment earlier.

--
| ___ Salad Dodger
|/ \
_/_____\_ GL1500SEV/CBR1100XXX/KH500A8/TS250C
|_\_____/_| ..74309../..18302.../..3184./.19406
(>|_|_|<) TPPFATUICG#7 DIAABTCOD#9 YTC#4 PM#5
|__|_|__| BOTAFOT #70 BOTAFOF #09 two#11 WG*
\ |^| / IbW#0 & KotIbW# BotTOS#6 GP#4
\|^|/ ANORAK#17 IbB#4
'^' RBR Landmarks: 12 Pts: 220 Miles: 914

 

It was somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "WavyDavy"

It's just a voltage meter, so yes, probably.

 

Dunno how the drag thingy works but I think it uses magnetic damping.

My guess is that a connector or wire is going bad so the tacho receives a
confusing signal. Might just be water in the electrics.

 

But it works fine from 'cold' and plays up *only* after its been working a
while.....

If it was a bad connection or water, surely it'd be playing up all the
time...?

Dave

 

So are these sort of things fixable or would it be easier (i.e. cheaper) to
just get another tacho from a breaker or can you just pop the back off,
change the oil for some new 10w/40 and Bob's yer uncle-type-stuff?

Dave

 

It'll be a bad earth somewhere along the line. Had exactly
the same happen on an RGV250 where it went all screwy because
of a bad earth caused by a corroded plug, and then again on
the 748 when I didn't tighten the battery cable on properly
after fitting the Optimate lead and the vibrations caused the
lead to jump and spark on the terminal which sent the tacho
crazy.

Check that first, then suspect a bad guage.

 

WavyDavy emerged from their own little world to say

Not necessarily. If the loom is routed near something that eventually
gets hot, which happens to correspond to the the location of the fault,
then it might take a while before it becomes evident. Electrical
resistance increases with temperature as well as the more obvious
possibility of expansion causing an intermittent connection.

I would initially go for the point where the tacho and/or sensor are
earthed to the frame/engine. This type of fault is typical of a poor
earth.

 

It was somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "WavyDavy"

Hum... most things are fixable, but I suspect that the manufacturing
technique used might preclude it; ie, made down to a price and not
designed to be taken apart - or more to the point, not designed to be
put back together.

The damper is likely a damping coil or magnet or a tiny spring, so
possibly fixable, but who knows.

Years since I pissed around with meters, so bear with me if I'm wrong on
this.

 

Yes, instruments do frequently have a tiny amount of damping oil in a
little dashpot for the needle.

This is one reason why you should never store them upside down - the oil
eventually leaks out and the needles go wobbly.

If your NS clocks have spent a lot of their time in Australian mode,
this could very well have happened.

And no, this is not a windup, and not based on experience - merely
repeating something I read in a classic rag. SWK will be along shortly.

 

Spot on. Totally.

The speedo on my 550 used to wobble all over the place for this very reason.
Not that it had been stored upside down at any time that I know of, but
because the damping oil had at some point in it`s life leaked out of the
dashpot that the needle sits in.

It is repairable, however. On the 550, I had to carefully lever off the
metal hoop surrounding the speedo body so I could get access to the innards.
Once I had access, carefully remove the needle, and you then come to a small
brass dashpot with a pin sticking out that the needle sits in. Unscrew the
top of this dashpot and that`ll come out with the pin. Now, what you have
left is the bit you need to refill.

The oil used in these things is very thick indeed. I ended up using the
dregs from an old bottle of gearbox oil that I had lurking around. It had
gone as thick as the Jism of the Gods, and I had to scoop it out with a
small spatula. Perfect.

Fill the small dashpot with it, carefully screw the top back on and refit
the needle. Whether it`s going to work is evident straight away by flicking
the needle across the scale and seeing how damped it is as it returns.

All good fun, and an interesting way to kill an hour or two.

 

I know someone who always had a problem hot starting a Ford Orion. In
the end we decided it was because the starter cable ran too close to
the exhaust manifold and would heat up. The extra resistance caused a
significant voltage drop at the starter motor and it wouldn't turn fast
enough to start the engine.