Honda cbf125 won't start or cuts out

[onejaz]

Hoping I can get a few ideas of what's up with my 2009 cbf125.

Over the winter I've had a few instances of it just losing power in 3rd gear. I'd be accelerating then the revs just drop and won't come back even if I fully open the throttle.
Within 5-30 seconds it'd kick back in and all is good again.

Also whether it's related or not, lately I've noticed on stopping for junctions etc that pulling in the clutch in first would make the idle revs increase a bit, and slightly letting it out would lower them.

Went out on it Friday and it started doing it straight away in first, so I had to pull over at my local Halfords as it was busy traffic and it kept losing all power.

They tested my battery and I bought a new spark plug in case it was that, battery was fine (less than 6 months old)

I got it to start if I revved it but it'd then just gradually die with the lights on the dash getting dimmer.
I left it there rather than walk it home in daylight, came back in the evening and started it but I only got the half mile home by revving it out in first and second as if the revs dropped in the lower half it'd die, if I had to slow down for cars I had to pull in the clutch but still rev the engine.

Put a multimeter on the battery today and its fine but the bike won't start, starter motor is kicking in.

I'm reasonably mechanically minded so I'd like to fix it myself, especially as I've just saved enough to pay for my proper license and I'd rather not use that to pay for someone to fix it.

Any ideas of where to start? Fuel pump sounds ok but could it be blocked? faulty stator?
Thanks for any help.

[jaffa90]

"""" just gradually die with the lights on the dash getting dimmer."""

What is the battery voltage reading when switched off and at 3,000rpm, with the negative probe on the metal frame and engine?

When was the last time the engine had new correct oil and filter and is the oil level correct ?

[onejaz]

It's 12.9v when the keys inserted and turned on and drops to 11.3v when pressing the starter.
I did put it on charge overnight just to make sure it was completely charged up.
I could only start it twice and both times it died before I could measure the voltage again but I'll try again in a bit as it won't start again now.

I bought the bike at 5000 miles and it's had fresh oil every 2000 miles (now on 13000) changed the oil end of last month and tripled checked the level.

Air filter is the original and quite mucky so could do with a new one, when I tried starting it today I had removed the filter to look at it so don't think it's that but I will order a new one.


Don't know if any of this below is relevant>

[Zen Dog]

I read a post a while ago (when I had one of these) that the charging system on the CBF is somewhat shitty/badly designed, and the person posting said that they'd upgraded it.

I don't know enough about electrics to say whether he was correct or not, but it might be worth getting hold of a wiring diagram and checking the charging system. Given that the CBF doesn't come with a fuel filter or an oil filter as standard, I can certainly believe it was designed badly.

The other suggestion I have for unspecified random electrical issues is the old classic, you may have a bad earth.
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Current - '94 VFR750FR (Dead), '00 VFR800FI, '11 600 Hornet - Previous - '11 CBF125, '10 Street Triple R, '92 MZ ETZ301, '05 TTR250, NSR125R, KMX125, "Honda" Win
My bike trip around S.E. Asia 2010/2011