Honda-SOHC
SOHC.co.uk Forums => Anorak's Corner => Topic started by: DomP on May 29, 2024, 02:44:41 PM
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I've fitted a Koso multifunction gauge to my cb550 with the rpm wire connected to the positive of one of the coils. I can't get it to register anything on the rev counter regardless of the settings I've entered. Has anyone else on here any knowledge of Koso gauges or similar set ups? Im trying not to bother Roo again😀
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Have you wired the rest of the functions up sure mine had a common wire for something but it was ages ago.
What model is it.
This was the one I used.
https://www.digital-speedos.co.uk/gauges-c4/motorcycle-gauges-c27/multifunction-gauges-c29/multifunction-gauge-db-01rn-p5
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All wired up and everything works except the tacho, it's a TNT D64 Paul.
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Aftermarket tachos on cars used to connect to points side of coil
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Aftermarket tachos on cars used to connect to points side of coil
I'll check later but I 'think' I got it right
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I'm running a Dyna S that came with it when I bought it, whether that affects things
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If it works on the LT side of the impulses will it not be related to the number of sparks generated for one crank rotation?
Not as such affected by the HT coil side?
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I'm not sure I understand Ted. The instructions are woeful, in the setup guide you have to select for 4 stroke and 4 cylinders by selecting options that go 0.5, 1, 2, 3, 4 but on my gauge there are .5 increments that don't relate to anything in the instructions. It's to chose the number of ignition per cycle. Clear as mud to me.
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A "standard" electronic tacho will count 4 lt pulses for 1 crank revolotion, the honda coil will pulse twice for one crank revolution so readings may well be wrong, also with the dyna there is a different amount of "dwell" or coil charging time which may afect the tacho operation, i cant comment on that as i understand electrical dohickies but not elctronical ones
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An electronic rev counter works by converting the rotational impulses into either a digital or analogue display.
A rev counter for a 4 cylinder car will not work on a 3 cylinder one though manufacturers might fit a circuit so it works on both. I fitted an Audi 100 GL car rev counter into my old Mini as both were 4 cylinder vehicles.
I assume yours will be specific for a 4 Cylinder motor cycle that uses the wasted spark system - not a distributor
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Here's the set up guide. Mine is an analogue rev counter Ted, I'm thinking of using the wrap around HT lead method of set up to see if that works but I'd rather the hard wired way. There are no instructions for wrapping around even though a wire is supplied for it
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I wonder if this would work
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The manufacturer of your unit need to employ an accurate translation for their instructions - those are gobbledygook.
My thinking is:-
If one set of points operates two cylinders with a wasted spark you are getting four signals for one 360 deg of rotation so setting 4 on the left side of the first table (4C-8P). If its a 4 lobe unit. or is it setting 2 FFS I'm lost already but...
Presumably if you get the setting wrong it will read either half the true revs or double .
Either way you should get a reading assuming the power supply wiring is polarity correct and earthed.
Update:- I keep changing my mind between setting 2 & 4 either way I cant see why you do not get some sort of output givig a reading
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I've tried 2 and I think I've tried 4. I've got it wired to the black with white tracer coming from the one coil, I think that's correct.
It's terrible isn't it Ted, Koso are a pretty well known manufacturer too!
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Presumably the unit itself has three connections?
Power and earth to the unit itself plus the impulse wire that measures the number of circuit impulses within the unit to translate that into the analogue reading?
I would have thought it ought to be connected to the blue or yellow on the points side - or do the instructions say on B&W side?
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I suspect the impulse measurement signal would be different if it includes the circuit through the coils unless it's designed to work on the feed side as this would not be affected by the coil resistance - your logic to connect on the B&W side makes more sense. Do the instructions help?
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The rpm is just the signal wire as the gauge is multifunction so has a supply and ground. The signal connection is what myself and Roo worked out but could be wrong
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I wonder if this would work
This is used on many current cars, tapping a phase on alternator to give speed signal of crank. Often on diesel that have no ignition to speak of.
Whether your kit can sense it from there I'd not know.
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Might be worth trying the impulse wire on the other side if the LT connection a blue say. The signal via the coil primary windings might give it more signal oomph?
Odd if no details of how many winds round the coil wire is needed in the instructions.
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I'll try that Ted, I don't have a blue wire coming from my electronic ignition though, there is one with a blue shrink-wrap.
I'm worried about frying the gauge though.
*Well I threw caution to the wind, tapped into the blue sleeved wire from the Dyna S and got a rev reading! Not accurate but I can work on that in the settings I think, it was a bit bouncy
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Is you rev counter designed to work with electronic ignition the switching signal profile might be unsuitable.
As you are dealing with an inducted circuit it might be possible to dampen it. Electronics is not my forte.
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It says its suitable for both, I think it's reading around half the revs on setting 2 which is 1 rpm signal per 2 ignitions so u wonder if I change it to setting 4 which is 1 rpm signal per 4 ignitions
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Deffo try setting 4 then. 👍
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I'll give it a try later Ted. So why don't they suggest connecting it up on the ignition side rather than from the coil I wonder, then again looking at the instructions I'm not surprised.
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Just a thought might be coil side for CB, other side for Electronic..
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Sadly setting 4 made no difference, only getting a reading when I raise the revs
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1 rpm per 2 signals should be correct i think
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1 rpm per 2 signals should be correct i think
That's what I initially thought Bryan, more research needed I think. At least I've got it to register some sort of reading
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Bring up my old thread as the weather has returned me to tinkering in the garage again, this time I'm determined to sort the rpm signal to my Koso gauge. I've been in conversation with the europe help desk and this is what they have told me is an alternative set up as neither of their other suggestions work. The question is are they suggesting I connect to one of the three yellow wires coming from the alternator? That seems like a recipe for a burned our gauge to me.
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Looks as you understand it, taking a signal from one of the phases of alternator.
This is quite usual though as many cars run that type. Most diesels with rev counters too as there was no ignition to read when they were less sophisticated. Many types have moved to running off crank sensor now and via ecu processor.
If that's their stated instructions it should be OK to try with their unit.
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Thanks, I hope it works finally as I've spent far to much time trying to get it working. Koso's instructions are absolutely laughable.
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It works!!! Thanks everyone for all your help, that's another hurdle overcome.
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So how did you connect the wiring to make it work?
Might be worth posting the connections/colours you finally used to get it working for the benefit of others here.
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It works!!! Thanks everyone for all your help, that's another hurdle overcome.
Well done and nice to get another piece of a jigsaw in place.
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It works!!! Thanks everyone for all your help, that's another hurdle overcome.
Well done and nice to get another piece of a jigsaw in place.
It is, now really just the carbs to get fine tuned, I did a quick float level test with clear aquarium airline and even though I set the floats using Julie's method I've got some running too low and at least one borderline too high. Carbs off again unless I fiddle around with them in situ
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So how did you connect the wiring to make it work?
Might be worth posting the connections/colours you finally used to get it working for the benefit of others here.
Yes, it would be useful info in thread if anyone else then searches for the same .
It should be any one of the yellow wires from alternator windings toward the rectifier Ted. Any of the three would give a "pulse count" to the tachometer if it's equipped to take that input.
I was working with someone on a car and didn't initially realise they did this. It had various input to ecu from electronic ignition etc but with tacho traced back to alternator. Thatt had a winding "tapping" on back of case that came from prior to rectified output post.
Peculiarly, he'd changed the pulley diameter on the alternator such that the rpm was showing different to crank speed ;D which won't happen on these Honda engines with winding etc being directly on crankshaft.
That had dome industrial head scratching going on ;D
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So how did you connect the wiring to make it work?
Might be worth posting the connections/colours you finally used to get it working for the benefit of others here.
I'm amazed Koso didn't suggest this in their set up instructions and that it has taken over ten emails to them to get this sorted, it really was as simple as running a wire from the rpm signal wire to any one of the three yellow wires coming from the alternator. I didn't get an accurate reading straight away but that is adjusted in the gauge menu depending on how many signals you are getting per rotation.
Instead Koso suggest either wrapping the signal wire ten times around a plug ht lead or connecting to either the blue or yellow wires coming from the points, or in my case Dyna S ignition, the wrap method gave no read whatsoever where as the ignition method gave me a fixed 1000rpm at any rev range.