SM/SX 125 2003 LOST SPARK?

[Jackypops]

Thanks for reading my topic.

I've fitted a new battery 9.5ah, wiring loom, both relays indicator and cut off. The side stand switch has been bridged. Bike ran for about a month until I tried to take it out the other day. My multimeter reads a voltage on the primary coil but loses it after a second. I only get one spark when I press the starter switch after that nothing, leave for an hour and I get the same symptom (sparkplug screwed into the head and another sparkplug in the HT led grounded to the head of the engine to check spark). Taken spark plug out of the engine, grounded it to the head and boom lots of strong spark. Once I screw a sparkplug in and test for spark with a different sparkplug I still get that one spark then nothing.

Any ideas?

[DAVID THOMPSON]

check steady power to cdi box and the plug the regulator plugs into the harness plug on my rt125 melted

the wire harness on mine 2002 is in poor shape

[Jackypops]

I have steady 12.4v going to the cdi when the ignition is on. My rectifier has no continuity between both brown wires but live has continuity throughout all the other wires on the rectifier

[DAVID THOMPSON]

my reference to the v/r plug was the fact that it had melted into a pile of plastic JUNK
and was passing no electric into the battery and the bike had less than 5000 miles on it

on my bike it is on the bottom of air box where it is hard to see

[Jackypops]

Months down the line it's still in the garage. Purchased new intake manifold because old one was cracked. Engine has been rebuilt, head was skimmed due to damage, piston ring was stuck but a little bit of sanding helped it move freely. Compression is 110 psi. Now engine back fires into the carb, like a popping sound out of the air filter.

As I still have the no spark issue will a voltage regulator being some what faulty affect this? The battery is fully charged when I tested it. Ive spent too much money on this bike and it's still a no go. Unfortunately the shim buckets were mixed up so hands down that may be the problem. Does anyone know the valve clearences? Thanks

[DAVID THOMPSON]

cdi boxes get really upset if they do not get proper power

[Jackypops]

For the CDI box; when ignition is turned to the ON position I can hear a very quiet buzzing noise coming from the box. With the primary wire off (power wire to the coil from CDI) the buzzing gets louder. Cleaned all contacts and even replaced both the connectors. When I first had a look at the bike the earth wire from the cdi to the coil was earth to the frame (2 bolts that mount the coil, one acts as a stud the other is drilled all the way through the frame, with the earth cable attached on the outside of the frame) I thought surely wasn't right so I reattached it to the earth body of the coil. Now I have occasional spark, strong spark with the sparkplug taken out the head and grounded to the valve cover, but weak sometimes doesn't spark after a fuel revolution.

[Far Far Away]

Hi,
Was this ever resolved ... I have a similar problem ...thanks