problems starting cold - revisited

SM, SX, RT, FunX, and models re-branded as ATK in U.S.

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problems starting cold - revisited

Postby 125SMash » Wed Nov 07, 2007 4:34 pm

this might very well apply to all bikes, but i'm posting it here hoping 125cc owners learned something particular about these engines..

a couple of months ago i had my dust collecting, rust growing bike cleaned out and reinspected.
it got a brand new battery, spark plug, fuel filter, and had its carburetor and air filters cleaned.

off the back i had some issue with it when it would only start on a full battery, and only if i didn't use the choke at all.
the mechanic advised that i cover the air filter completely (??) to get better luck if it gives me trouble.

i brought it back to properly install a battery charged GPS on it, as well as try putting in a higher CCA battery,
and he found an air intake adjustment by the engine, and adjusted it (i'm guessing thats why CLOSING the airfilter seemed to work in the past).
also the idle had to be readjusted because somehow it was set so that when i moved the steering all the way right, the bike accelerated (!!).

with all this discovered and re-done i was able to ride fine for a while with the warm temps around.

now that its cold again, on a full charge, without bothering the choke, the engine will start and run for 1-2 seconds and die.
If i try to start again, the electric motor is squealing, and the exhaust is puffing, but only while i keep my thumb on the starter.
I think the puffing is only happening because of the compression by the electric starter, and no ignition is actually taking place (correct me if i'm wrong)

opening the choke does not help at all. neither does opening the throttle while starting.

all this while in warm sunny weather the bike starts right up without a problem.

i've been told that an engine with low milage such as this, barely 40 km, may still be needing breaking in.
of course the catch 22 is, i cant ride it to break it in if its not starting..

i've read some advise online to use a drop of starter fluid or even a dorp of gasoline on the tip of the spark plug, but then i also read a lot of 'no-no' comments about this elsewhere.

anyone have any insight

any orthodox to unorthodox ideas are highly appreciated.
2002 MZ 125SM
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Re: problems starting cold - revisited

Postby DAVID THOMPSON » Wed Nov 07, 2007 8:32 pm

read this post i think cdi box is not getting proper power
the way the new site handles pictures requires use of scroll bar to see all the posted pic

viewtopic.php?f=4&t=2085

please note that a jumper from pin 3 rt/sw(red/black) to pin 5 rt/ws red/white
by passes this relay and causes sidestand safety
switch to be bypassed but will allow you to see if relay is not supplying
proper power to cdi box
if bike starts ok replace relay per the above post
ar dave
may not be the problem but a good place to start
Dave 2002 MZ RT125+1995 Saxon Tour(500cc)
1997 MZ 660 Traveller+6/13/09 WV USA
"IN the end times the IDIOTS will be in charge
of everything"
"I like the road less traveled if it's PAVED!"
wd8cyv at yahoo dot com
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Re: problems starting cold - revisited

Postby 125SMash » Sat Nov 10, 2007 2:56 pm

thanks for the response dave.
congrats on making the moderator!

i'm afraid the relay / CDI pics are somewhat over my head..
(by the way, if you click on the pics, they appear in full dimension, no need to scroll)

i did try to start it with the kick stand up, clutch pulled in etc, all to no avail.

until out of desperation i removed the eat again and covered the air intake with my hand.
the result sounded much better but still no start, and today is not that cold.

i'm recharging the battery again to try in a bit closing the air filter, but this makes me wonder if despite all the air flow adjustments made, maybe choke is somehow responsible.

you mention you couldn't start with the kick stand down. did it sound like what i described, or wouldn't start / revolve at all?




*UPDATE*

ok just tried starting again.practically sealed the air in take with my hand and the engine started right up.
except i had to keep the throttle open a tad otherwise it would die.

i held it open for a few minutes gradualky releasing and opening up a notch if it would sound like its about to stall.
tried closing own the choke notch at a time to help it run, and for a moment it sounded liek it helped. then it just died out again and i couldn't restart it no matter how close i held the air in take. soon after the battery died again.

everything seems to point that its getting too much oxygen. anything you can think of that would requre it to run THAT rich?
2002 MZ 125SM
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Re: problems starting cold - revisited

Postby DAVID THOMPSON » Sun Nov 11, 2007 12:03 pm

take a look at this post
the most trouble i have had getting started was from bad gas or this
ar dave
carb info for 125cc but of interest to all
viewtopic.php?t=918
Dave 2002 MZ RT125+1995 Saxon Tour(500cc)
1997 MZ 660 Traveller+6/13/09 WV USA
"IN the end times the IDIOTS will be in charge
of everything"
"I like the road less traveled if it's PAVED!"
wd8cyv at yahoo dot com
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DAVID THOMPSON
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Posts: 5161
Joined: Sun Nov 23, 2003 11:01 am
Location: Parkersburg, West Virginia USA .questions answered MZ 95 up, BMW 1953 to 1979 and ham radio WD8CYV


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