On Jun 12, 1:27 pm, Volker Bartheld <
dr_vers...@freenet.de> wrote:
> Hi Tiago!
>
> [My newsreader just crashed, so please apologize the short&impatient
> version...]
Hi Volker!
:)
>
> On Tue, 12 Jun 2012 06:32:00 -0700 (PDT), Tiago wrote:
> > Should I post this on FB? ;)
>
> Unless there is a bike repair party...
lol! sorry about the previous incident, it wasn't intentional.
>
> > I'm talking about my street bike, '02 Honda CG125 with 95k km ( almost
> > When it's cold, it start first kick (or first couple seconds pushing
> > When hot it starts even easier and sustains normal idle. I think I
> > could start it by hand when hot.
> > But when it gets really hot (after 15 minutes riding) it loses power.
> > It feels like it's misfiring or getting fuel starved.
>
> Valve freeplay is set correctly?
yes
> Compression rings, oils seals, valve guides intact?
I guess they are, a bit worn, but in one piece.
> Probably coal deposits on the valves?
I had that problem before, but if that was the cause, it wouldn't work
fine when cold.
> Decompression mechanism/lever (if present) OK?
not fitted, it's just an old school pushrod style 125cc four stroke
designed in the early 70s.
> No hairline cracks in the cylinder head/along the spark plug threads?
I checked that, no visible cracks
> Does it lose much oil? Coolant?
air cooled; doesn't lose a lot of oil, I add 200ml every 800km (two
weeks worth of commuting)
> You are sure that the ignition coil and spark plug boot are fine?
No, they are my prime suspect.
> Already checked the stator/magneto/lighting coil? *)
battery seems to be getting charge and headlights are directly
connected to lightning coil (dims when engine is idling)
> Kill switch/sidestand switch OK?
not fitted
> What about cable routing especially along parts that get hot?
I'm positive this is not the problem
> You could also check if the problem changes when pulling the choke or
> removing the air filter entirely. Sometimes a stuck/leaking choke mechanism
> leads to strange effects...
If I enable choke with warm engine, it dies immediately. I replaced
all carb rubber parts... I don't think it is carburetor.
>
> If needed, take off the tank, fabricate a DIY replacement from a PET/PP
> drinking bottle with nozzle and hose, attach this to the carb. Also helps
> detect venting problems with tank and carb.
I am leaning towards either mechanical or electrical, I don't really
think the problem is carburetor. If it was venting, it would get
"good" after opening the tank cap, I tried that and doesn't get any
better.
>
> New spark plug and air filter will surely rule out a few candidates. **)
Will try that later today... And report back the results.
>
> Good luck fixing your bike!
Thanks!
>
> Volker
>
> *) My KTM hat intermittent problems when warm/hot and I blamed the crappy
> Dellorto carb for it. When it finally broke down in the middle of nowhere
> (yes, that also possible in Germany!), it turned out to be the SEM-Stator
> (dry version).
ouch, too many "middle of nowhere" places here, some that I really
don't want to be stranded. CG's stator from 2000 on are the wet type.
>
> **) 4S plugs normally last for a long time and then fail immediately. If my
> YZ426F or RMZ (or any other japanese bike) fail to start, it's 99.9% the
> spark plug.
It's weird, there's something wrong with my bike. Hypothetical
question here... Suppose that there is a small earth connection made
of carbon, from the center electrode of the plug to the threaded part,
over the porcelain insulator. A small enough connection that usually
the spark jumps the gap, but some sparks take the earth path... It
feels like that, feels like someone had shut the engine down and then
re-started. What's odd is that when that is done intentionally holding
throttle wfo, there is a loud bang on the exhaust. No bangs here,
quiet or loud. Feels like it is sparking only every other cycle... If
today's parts doesn't fix, I'm removing the mousetrap from the wallet
and reach out for a high performance ignition kit (about 80usd): CDI,
ignition coil and all new wiring.
I just love to troubleshoot electricals... As one friend said to me
once: "the electrons are dumb, if you let them loose, they won't do
what they are supposed to".
:)
-- Tiago