Reply To: Gt125r not starting
Ok will do thanks.
While you wait for those things….
Get your meter out….
Stage one = Switch to 20K ohms
Ground frame (meter -) & HT wire (meter +) = Ohms ?
Switch to 10 ohms (Ten)
Ground frame (meter -) and & Coil Terminal Spade = Ohms?
Now you have tested Secondary and Primary Resistance of the coil. Tell us and we will advise if the coils are in OEM spec or not.
Next…….
Remove HT Cap from the coils (unscrew anticlockwise)
—> Switch to 20k ohms
Meter (-) in one end of the HT cap and Meter (+) on the other end of the cap.
Tell us the ohms of the HT cap by itself without any coils attacted to it.
I have a funny suspicion that the harness probably needs a thorough inspection (hard to do while its still on the frame) , it’s a long sucky day taking it off but…….
– Get mannol tape = And overtape the whole harness. It’s a very good tape! (Mannol Harness Tape)
Korea’s own tape for the harness is not that great on carby bikes. and the wires easy get frayed or grazed up on the chassis if they get exposed (if they get exposed enough, they get chaffed , and if a naked copper line is exposed, it shorts the fuse or does something to the bike that it gets harder t start next time (as it’s annoyed)
– Get Halfords Contact Cleaner = Get crazy with it until you see your pins free from muck. = Dirt, debris inside plugs = No signals can pass thru , bike won’t start in some cases.
– Euro Carparts , Amazon PRIME 1 Day, Halfords = get ACF 50 = “whatever plug” , i mean “any plug” on the bike , add a very tiny drop of ACF50 inside and it will thank you for preserving its pins , sometimes “oxidization” happens inside plugs. Yes you can even ACF50 the battery terminals.
Do NOT use WD40 or any other substance = It will guarantee flames go up soon.
You should have your clutch switch by now.
Next , what else cuts sparks off besides loom?
– Side stand switch (bypass it, ) if yes already then good! = But remember the area that’s bypassed (ie at the plug , could have debris , double check it. It is very cruicial. Most newer 2015+ bikes that have trouble starting is because of this stand bypass being done poorly by last keepers)
Hint = If sidestand bypass is not active or side stand switch is not there, the “WHITE RPM DASH” will not move at all ….. It stays “zero revs”
Hint 2 = If there is sparks , the RPM gauge will start moving up, 0, 2, 3, 5, 7k rpm (in a funny fashion) then bike fires up
(Don’t worry the starter motor still spins at 500-700rpm)
Hint 3 = Rpm needle is moving up, then sweeps down , moves up , while cranking = You have no fuel coming out. So bike is dry sparking.
CDI = Can cut sparks off when its fautly , can’t start without it. However , it should be fine , it will be the LAST object to worry about.
Stator = “Pickup sensor” (2 Pin Plug) from the stator is the “beginning” of the sparking system. = GT125RC stators are quite smaller , 18 pole units , they usually have the pick up values similar to EFi bikes (80-110 ohms is good for the carby 125 in general)
Upgrade ones (would be around 120-140 max) , (as was the case in old gen carbies)
Yellow wires = charge system = Beyond 1 ohm on any yellow wire ice cold means the stator is on the way out. Normal range is 0.5-0.9 ohm on a single yellow wire and the 3 wires must have identical values (if one wire is out of spec, the whole 3 phase unit is not good)
Hence Simon cautioned to have a good regulator next too. Stator & Reg usually go hand in hand (married). (as is the Ignition Coil & HT Cap need each other but a faulty HT Cap with a good coil means no sparkings or temperamental bike)
Clutch Switch = On the way, this cuts sparks off anytime the bike is running or turned on , this switch must work at all times.
Neutral Sensor = If this unit is faulty , the 2017 bike doesn’t want to know. It won’t spark.
Out of the bikes i usually fix , the New Shape 2014-2018 GT125s are notoriously hard to start , if they sense even one small thing out of place , the old gens can even fire on one cylinder and force themselves to start surprisingly or bump start easily in to 1st gear after a rider is pushed a few yards around in the yard.
I am digressing, i hope this helps!