Ybr 125 custom question

[cresad]

Hi
I'm trying to sort out a problem with my daughters bike , a 2015 Yamaha YBR125 custom. The problem she's having is that sometimes turning the ignition on it doesn't connect and she can't start the bike , and occasionally while she's riding it will cut out losing all power.

I had to change the ignition switch a couple of weeks ago ( she lost her keys ) which has made it worse but it was happening before. I got her to watch the engine light count and she said it shows 19 - no connection between ignition and ecu. I've checked the wiring from the ign. switch to the ecu and get .66v , I've sprayed WD into the barrel and used electrical grease on the plug connections with no difference. I'm testing the battery as well ( just in case ) and it shows low 12v when off and with the engine running 12.5 - 12.7 v at 6000 revs. The clutch switch and side stand switch are both working.

My main experience comes from car mechanics , and I'm wondering if the charge rate is low? Were not getting the neutral light coming on very often , could it be a problem with the switch ( related )?
Am I on the right direction with the ign\ecu or charge system?

Thanks for reading as I know it's abit long winded.

Adam

[stinkwheel]

I'd assume the ECU is supposed to be getting battery voltage from the ignition switch so that narrows it down some. Is battery voltage getting into the switch? Is it getting back out of the switch? After you've confirmed the switch is good, you'll just need to chase it through between there and the ECU using a wiring diagram. See where the voltage disappears.

Also have a look at the main loom as it passes the headstock, it sees a lot of movement and you can get chafing through insulation or broken wires. See if wiggling this area reproduces/removes your fault.

The charging rate is poor, I'd expect closer to 14v with revs. I'd almost go so far as to suspect you are missing a charging phase there, or the battery is on its way out.

I'd be having a good look at the connector block for the reg/rec unit (bikes have a 3-phase alternator with a seperate regulator/rectifier unit). You can test the alternator output with your meter, there are static and dynamic tests you can do.

Find the reg/rec and disconnect the connector block. You can't really test the reg/rec itself without specialist equipment but you can test the alternator. First look for scorching/melting/corrosion at the connector block.

I'm not sure of the wire colours but it look like there are 5 pins. Three of them will be charging phases, one will be an earth, the other will be a hot live so you should be able to work that out.

You should have battery voltage at the live and good coninuity with earth at the earth.

The other three will be connected to the alternator windings. With the engine off, check resistance between each pair. You should have a low but roughly equal resistance between each pair. None of them should have continuity to earth.

With the engine running, you should get an increasing AC voltage between each pair as revs increase, can be in the 30-50V range so watch you don't get a dunt off it.

Anything different from that and you have a problem with the alternator.

Also worth checking your earth connections, both to the battery and to the frame because bikes are way more prone to corrosion in this area. Bad earths can cause a wide variety of electrical gremlins
____________________
“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.

[cresad]

Hi

Thanks for the reply. I have already changed where the earth lead is bolted to the bike , it’s now on the rear engine mount to frame ( it was on one of the clutch outer casing bolts ).
I’ve checked the plugs from the reg\rec and from the stator plus a few others and can’t find any burning or melting. The battery voltage at stand is measuring 11.5 and with the ign on 11.75.
I’ll have a go at checking the stator over the weekend and if nothing shows up all I can do is try changing the battery and go from there.


Thanks . Adam

[stinkwheel]

A resting voltage of 11.5 is a sick battery. I generally change them if it drops to below 12.3 after a charge.
____________________
“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.

[WD Forte]

your description are poor
spin up no fire or no spin up?

the fact it also cuts out suggests a spin up. no fire situation
Also you should see close to 14v across the battery terminals when running at tickover on a healthy bike.
I did on the last YBR I worked on.

The ECU wont enable ignition if it doesn't 'see' a low/ground on the black/white wire.
The typical fix for code 19 is to cut the black and black/white wires
at the switch and join them together
But
This means putting the side stand down when running will not cut the engine or stop you riding with the side stand down
but many folk seem to accept this at least for the short term

Best practise is to strip it all apart and test/repair/renew any/all
faulty components
____________________
bikers smell of wee