Electronics advice/help needed... now sorted by new battery

[map]

I just have an issue with my winter bike, Kawasaki GT550.

Now to give a little diagnostic history.
Recently battery has not been holding charge to start the bike. Is ok for 3 to 4 days then not enough oomp (technical term) to start. Appears worse when wet/damp. At the time suspected a leak to earth from a worn wire, now not too sure!

Anyhow the other night got home with a few backfires, something that not normally occurs. Last night bike died going down the road after another backfire. Eventually restarted (yes, did check petrol). Limped home with electrics (lights) appearing to die at one point and then only doing 60mph. That was suspiciously like running on 2 cylinders.

So, I'm thinking 3 possible suspects.
1) Coil
2) Rectifier
3) CDI unit

Now rectifier may explain battery problem, as in not being sufficiently re-charged. CDI may explain the poor running/2 cylinder issue (as would coil).

So wanting to know how to check it over diagnostically. Have meter, just want to check where to stick it

Thanks in anticipation for any/all useful comments.

MAP
____________________
...and the whirlwind is in the thorn trees, it's hard for thee to kick against the pricks...
Gibbs, what did Duckie look like when he was younger?

[jjdugen]

Classic reg/rec failure. It will cause misfires (or even terminally damage the CDI, blow bulbs and damage the battery, sound familiar?).
To check the reg/rec monitor battery volts at tickover~13V DC, 3000 rpm ~14V DC. If it is significantly more the reg has failed, if your battery volts stay at around 12V or less.. it has failed.
____________________
The CBR900RR has been sold. Aprilia Falco worms its way into my heart.
Try Soi 23 on Amazon for a good read.... Self promotion? Moi?

[Fizzer Thou]

There should be three similarly coloured wires coming out of the alternator.Measure across any two wires for approximately 17vac.If these are all about the same then this discounts this unit.

If the voltage across the battery terminals at tickover is below 12vdc,suspect that one of the rectifier diodes are duff/open circuit.

As has been said,if the voltage across the battery terminals rises way above 14vdc then suspect the regulator.

https://www.electrexworld.co.uk/acatalog/Online_Catalogue_Regulator_Rectifier_206.html

Is the battery known to be good?Have you tried substituting the battery?
____________________
Just talk bikes.What else is there?

Always have a 'Plan B'

[map]

Thank you for the replies so far.
The plot thickens...

Apparently my multimeter has gone walkies so could only test with one of those LED battery testers for cars/bikes.

Just on battery up to the 12v lit.
On tickover the 13v LED lit.
With a little revs the 14v LED flickered on. Not a big glow but lit.

So recifier would appear ok.

Now tried to start this morning and fired up and then died (it happens). Tried to restart and not enough oomph in battery left.
So I'm thinking now duff battery (less than 6 months old though) or my original thought of a leak to earth. There was a lot of dew/damp around this morning which maybe contributed if a short.

So any other ideas on detecting a piece of worn wiring loom. Plus this also doesn't answer the other issues of backfires and poor running so any other ideas welcome.

Once a track down the multimeter I'll dig out the Haynes manual and check the alternator voltage as suggested.

As said, any help appreciated

MAP
____________________
...and the whirlwind is in the thorn trees, it's hard for thee to kick against the pricks...
Gibbs, what did Duckie look like when he was younger?

[map]

A quick update and this is really starting to annoy me.

Got home yesterday evening and just thought I'd give it a quick prod. Battery had just been left in bike, not recharged.
Bike started first push of the starter, no hassles.

Found the multimeter. It had been put somewhere 'safe' (I think we all know what that means).
Measured voltage on battery. Engine off about 13v. Engine running tickover and it was about 14v. However, add revs and it actually dipped to 13.5v. Tried this several times and it was consistent.

So that would again indicate regulator/rectifier as initially thought.

Could not detect any current between -ve connector and battery. Continuity/resistance between -ve battery (connected) and frame appears good.

So I guess I'll be sourcing a rectifier, fitting it and then retesting the voltage at the battery.

MAP
____________________
...and the whirlwind is in the thorn trees, it's hard for thee to kick against the pricks...
Gibbs, what did Duckie look like when he was younger?

[Fizzer Thou]

I would not jump to the conclusion that it might be the rectifier too soon.If you have the manual to hand,check to see what is coming out of the alternator first.If one pair has a below the specified output then that could be pulling down the overall output voltage.If when you perform a continuity test on that pair of windings you find that it is out of spec compared to the other two pairs,then you would need to look at maybe having them rewound by maybe https://www.westcountrywindings.co.uk/

13.5vdc across the battery at tickover is not that shabby.Sometimes a battery will 'recuperate' after a period of not being used.If there was any leakage when the ignition was turned off this would have drained the battery quite easily.Conversely,if the had been any drain back through the rectifier then this too would have drained the battery.

Check to make sure that there is no continuity between any of the alternator winding outputs and a good chassis earth.If there is then this will drag down the overall voltage output after it has been rectified.
____________________
Just talk bikes.What else is there?

Always have a 'Plan B'

[map]

[finpos]

Form the sounds of it - it is most likely the battery, however new it is.

The problem is you cannot test it with a duff battery because it will appear to odd things*, so see if you can test with another one - even if it's a car battery connected with jump leads. If you do this, then disconnect the old battery because you don't want it in the circuit causing grief.

* odd things may include you seeing the regulator kick in - it'll sit and do nothing until the voltage gets to 14 odd volts, then it will suddenly start dumping current to earth - which means you may see a small drop in voltage, which you do indeed seem to be doing.

f.

[stinkwheel]

Check the main fuse holder and the wire leading into it (at both ends) for corrosion.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[jjdugen]

Agree that the regrec sounds OK. I've seen this on quite a few R/R's. Best test is to turn the main beam on then rev to about 3-4K. If the voltage holds steady and does not dip below 13 volts then its working fine (and is actually 'kinder' to things like bulbs).
It is pointing to a battery that is not holding full charge, but could be a main earth that is a bit corroded and going higher resistance when left in damp conditions.
____________________
The CBR900RR has been sold. Aprilia Falco worms its way into my heart.
Try Soi 23 on Amazon for a good read.... Self promotion? Moi?

[map]

Just to finish this entry.
Touch-wood the issue us sorted with a new battery as suggested above.


The battery was not holding its charge so needed to replace anyhow. If the engine didn't fire on the first press of the button then not enough oomph left for another go.

New battery and appears ok for the past few weeks.
Also found cable connecting negative to bike frame was corroded and on inspection just fell apart. So replaced that as well.

I suspect I could have diagnosed this quicker if I'd been aware that the battery had fallen off the shelf while recharging This fact was pointed out by my son after new battery bought (think it might have been the cats getting in the garage).

So, thank you all for your assistance

On a separate note can anyone tell me how to remove the reg/rectifier should I need to in the future. Found it mounted way below the battery box in the frame. Doesn't seem much room to put in a socket. Mounting seems directly into bracket welded to frame.
____________________
...and the whirlwind is in the thorn trees, it's hard for thee to kick against the pricks...
Gibbs, what did Duckie look like when he was younger?