Problem starting (Honda CG125)

[Moebius]

Hi all, I'm having an issue starting my 2005 Honda CG125. I've had this issue on and off since I got the bike second hand a couple of months ago.

Every once in a while it'll just start clicking rapidly (it's an electric starter), as if the battery is too low or it's not sparking or the motor is screwed up in some way.

Initially when I started to dig into it I noticed that the wiring / bullet connectors on the starter were a bit dodgy (and in fact one disconnected) but I fixed that up with the help of the lovely peeps on this forum and an electrical mechanic mate, and it sorted the problem... temporarily. Then it started struggling to start again and I checked the battery and it was below 9 volts, so I got a new battery installed. Worked okay for a day or two and then started having problems again. So I decided to take a look at the carbs and found some water inside, which I got rid of (it must have been kept outdoors before). Again it started and ran fine for 4/5 days but then, again, it's started having trouble today.

I'm at a loss at this point, short of completely taking the engine apart - which I don't think I can do - I'm not sure what else it could be. Here's a video of what's happening when I try to start it... Anyone have any ideas / suggestions (not incl. battery and wiring, which I know are fine)?

https://youtu.be/32HQCXKC2FA

Edited October 6, 2020 by Moebius

[skyrider]

fastbob will be along shortly he will sort you out he is the cg genius

[dynax]

Probably need the starter cleaning or replace the internals with a refurb kit, easy enough to do as i did mine last year

Go onto wemoto and select your model and look under the electrical system for the starter contact set, but give your existing one a clean up first as that's all it might need

[Moebius]

Cool, will have a look at wemoto - cheers!

[fastbob]

First thing to try is to remove and clean both ends of both battery leads with sandpaper and refit them . To be honest though , that actually sounds like a simple case of flat battery . As Dynax has said , you could split the starter motor and rather than spend any money they usually just need a very good clean . Here's one I did the other week . The copper bit is what usually needs attention but use only the finest Wet and Dry paper ( 2500 grit ) If the problem persists even with a new battery then it could be the charging system . This is where things get a bit more mechanical but I'm happy to guide you through the process of fitting a new Alternator coil .

[Moebius]

First thing to try is to remove and clean both ends of both battery leads with sandpaper and refit them . To be honest though , that actually sounds like a simple case of flat battery . As Dynax has said , you could split the starter motor and rather than spend any money they usually just need a very good clean . Here's one I did the other week . The copper bit is what usually needs attention but use only the finest Wet and Dry paper ( 2500 grit ) If the problem persists even with a new battery then it could be the charging system . This is where things get a bit more mechanical but I'm happy to guide you through the process of fitting a new Alternator coil .

Cheers mate!

I'm certain it's not the battery, but it could be the charging system. I'll try to give the starter motor a clean first and if that doesn't work I'll come back for some guidance on the Alternator coil as I have no idea about that!

[WD-40]

Did you measure the battery voltage? The starter relay clicking like that is usually because the battery voltage is low.

[dynax]

Did you measure the battery voltage? The starter relay clicking like that is usually because the battery voltage is low.

 

Not always, mine did the same but it was the starter motor carbon brushes that were seized and not making proper contact on the commutator

[Moebius]

Did you measure the battery voltage? The starter relay clicking like that is usually because the battery voltage is low.

Yep, had a new battery installed less than a month ago and checked the voltage last Thursday and it was totally fine (also rode it Thursday, Saturday, and Monday all fine, no trouble starting).

[James in Brum]

There are some YouTube videos about checking the voltage to see if stator or regulator rectifier are working. At least for my bike. Worth a check.

Also an old thread on head of me being talked through checking it.

[fastbob]

Did you measure the battery voltage? The starter relay clicking like that is usually because the battery voltage is low.

Yep, had a new battery installed less than a month ago and checked the voltage last Thursday and it was totally fine (also rode it Thursday, Saturday, and Monday all fine, no trouble starting).

 

Strip and clean the starter motor then .

[Moebius]

There are some YouTube videos about checking the voltage to see if stator or regulator rectifier are working. At least for my bike. Worth a check.

Also an old thread on head of me being talked through checking it.

Thanks for this - looks like you were right on the regulator rectifier suggestion and I think I've fixed it (although I'm not holding my breath - we'll see if it's still starting fine in a week or two!).

I cleaned the starter motor and confirmed that the brushes were fine / not the cause of the issue, and knowing that the battery itself was fine the only remaining unknown was the charging system - chatted to another friend (the guy that helped me with the wiring before) and he was sure that it was discharging after rides and that's why the voltage / battery was generally reading fine before and shortly after rides but then dropping a few days later.

He had a spare regulator rectifier from another honda and gave me that to replace the existing one with and sure enough it's now keeping charge steadily - have checked it before and after rides and also left it for a couple of days without riding and the battery has remained fine.

Fingers crossed it stays that way and this is the end of the issues!

https://youtu.be/bx2a7UunP1s

[WD-40]

You could get one of those cheap voltage gauges from ebay to keep an eye on the voltage as you ride