CBR125R cutting out at idle when warm, things to check?

[VirtualMark]

Ok so I have a strange problem here. I have a 2016 CBR125R with only 3500 miles on the clock. I've rode it a handful of times in the past few months just to get it moving as selling a bike is tough at this time of year, but it's not my main bike as I passed my test last year and have more fun bikes. So it has spent a fair amount of time doing nothing.

Anyhow, it rides fine, no power loss or anything. But once I've rode it for a few minutes, the engine will cut out when I stop for a while. The tickover misses every now and then and eventually it stalls.

It's not old fuel... I filled it up the other day, so that's not the problem. The only thing I did that worried me, the other week I bought a trickle charger off Amazon just to keep the bikes topped up over winter(I have 3 bikes), and left it to charge. When I came back there was a smell, and I noticed the battery was smoking a bit! So the trickle charger had overcharged the battery, I left the lights on for 20 minutes or so until the voltage dropped. Still, I think I may have knackered the battery.

The bike starts first time every time, and as I said it rides and drives fine. Could it be the battery causing the idle to cut out when the bike is warmed up? It runs fine when cold, I'm stumped on this one.

If not the battery, anything else to check? I don't see any leaks, and it only has 3500 miles so I doubt it's a serious mechanical problem. Thoughts?

Thanks.

[billinom8s]

Battery is a part of the running system, unlike a car where once it's started you can remove it.

If you've damaged a cell with over charging then the bike more than likely wouldn't start. You could of damaged the charging Circuit or even melted a plug, this would give you a possible intermittent Circuit causing the Bike to cut out.
Could also be a sticky choke and blocked air filter.

[Mr Moo]

If you've let the magic smoke out of the battery it is [Censored].
The runningcutting out issue sounds like carb needs tuning properly.

[Jug]

If the battery could power the headlight for 20 mins and also start the bike then it is almost certainly not the issue here.

A quick search of google shows this seems like a common issue. Could be lots of things... fuel tank breather pipes kinked so pulling a vacuum in there, ignition coil is a known issue.

My thought are that this is not a problem that can be sorted over a forum, you probably need to get the bike in front of someone who is familiar with those bikes and then try things. It might even be necessary to swap out components one piece at a time until you find it.

One thing that you have in your favour is that the symptom is repeatable, so you can make progress in tracking it down and you'll know when you've found it.

[TLS-Moose]

Simples. Don't leave it ticking over for long periods, sell it. Problem gone

[Mervin]

If the battery could power the headlight for 20 mins and also start the bike then it is almost certainly not the issue here.

A quick search of google shows this seems like a common issue. Could be lots of things... fuel tank breather pipes kinked so pulling a vacuum in there, ignition coil is a known issue.

My thought are that this is not a problem that can be sorted over a forum, you probably need to get the bike in front of someone who is familiar with those bikes and then try things. It might even be necessary to swap out components one piece at a time until you find it.

One thing that you have in your favour is that the symptom is repeatable, so you can make progress in tracking it down and you'll know when you've found it.

fuel tank vacuum is easy enough to diagnose , when it stops open the fuel cap if there is a sudden in rush of air ( sucking sound ) then you have that problem

[Kata]

Knackered plug?

Tick over too low?

Does it stop if you keep revs up?

[MikeZ]

I would 1st try (as Kata suggests above) just upping the tickover a bit, some bikes do tick over low if it's cold and not regularly used.

[VirtualMark]

Knackered plug?

Tick over too low?

Does it stop if you keep revs up?

I'd be surprised if it was the plug as it's only on 3500 miles from new. But I've bought a service kit anyway to replace the plug, filter and oil. I also bought a new battery as from what I've read and people here say I probably knackered the battery when it smoked.

Yes it stops if I keep the revs up. I could up the tick over but isn't that treating the symptom rather than the cause?

I'm wondering if I possibly messed up some electronics when I charged the battery... as I didn't disconnect it from the bike. Is there anything obvious I could check with the electronics?

[Jay]

Replace the battery is probably the best option.... A cheap fix....
Have you modified the bike in anyway (electrical)? if so....put back to standard.... and start from there.
Jay

[billinom8s]

Wires and plugs from reg/rec to stator/genny

[VirtualMark]

Ok I've replaced the battery... still has the problem. It got worse today, I opened the throttle quickly while going about 50mph... and it bogged down. From what I've read I think it may be the coil, thoughts?

[Robbo87]

Back to elektrickery basics:
1. Have you got a multimeter and do you know how to use it?
2. If yes and yes then check voltage output of the battery before anything else. You need a reading at the fat end of 12 volts eg. around 12.75 of 'em.
3. Start bike. At tickover with no draw on the battery e.g. no lights, flashers etc. you should have a reading of at least 13.8 volts, preferably a tad more.
4. Still on tickover, switch on all electrics e.g. full beam headlights, flashers & brake light. Your voltage reading should drop to no less than 13.5 volts.
5. Raise the engine rev's to around 40% of max': Voltmeter should be reading around a couple of points or so higher than whatever it was at 4 (above).

For comparison, my Triumph's voltage readings from 2 to 5 above are: (2)12.84, (3)14.15, (4)14.00 and (5)14.05.

If you're not getting voltage readings around the above lines then you have either a generator fault or (and more likely) a regulator/rectifier fault. Before you start any major digging in to that side of things, check every, and I mean EVERY, connection from the generator to the reg/rectifier, also the from the reg/rec to the starter solonoid and any common earths (or ground wires if you're of the Yank persuasion) you can find - make sure there's no dry joints or evidence of overheating, it's a common fault with bikes, much more so than with cars.

If all the above checks out fine, then look for the next simplest electrical cause, starting with the ignition as mentioned by Jug.

Then it's fuel check time; there's a myriad things to look for so start simple, blocked breather? Cracked or bent vacum tubes? Clogged fuel filter? Gummed up carb' and/or jets?

Finaly, don't keep any bike on a battery charger, full charge or trickle, 'they don't like it on 'em Captain Mainwaring' (to paraphrase Clive Dunn) - well not for long anyway 'cos it'll fcuk yer battery. Use a decent quality battery tender instead. I use Oxford 'Oximisers' on my two. Also, run the engine up to temperature regularily. Bikes are like us, they need a bit of a workout now and then or they get all temperamental.
Good luck, and let us know how you get on.

[VirtualMark]

Ok firstly, thanks for all the help and replies.

I serviced the bike yesterday, changing the air filter(didn't need doing), oil and spark plugs. I also checked the coil contacts, they were a bit dirty so I cleaned them up.

Bike is now running ok, doesn't cut out anymore at all. So it was either the spark plug or the contacts on the coil.

Thanks again for all the help!