Reply To: Issue with hyosung gv 125cc – GV125-S EFi Bobber
Then i would assume you have faulty coils ?
Swap the front and rear coils ?
If that’s true, it time to get a new coil and probably new spark plug caps (as yes the coils can kill them) – NGK ones are too recommended,
Since these bikes came out of the factory we always get orders for the rear coil and pair of plug caps. The rear coil fails first as they wasn’t put on properly and the ECU can’t always tell you its a coil problem.
Sometimes you may need to also make sure the regulator is doing “14.2-14.5v” MAX & LOWEST , if it falls outside 14v in any revs , you will face more electric issues and possibly a slowly dying ECU as it’s the most voltage sensitive of all.
Do this with a fresh set of CR8E plugs (yellow box) = DO NOT use “CR8E-IX” (Blue Box) as Hyo 125’s don’t like em. Surprisingly yes the Stock plug or LASER NGK plug is way better for the injection 125cc. Carb Models are hit and miss most of the time.
If it has CR9/CR7 etc = bin them straight. CR8E only.
Keep us posted , we will get to the bottom of it 😉
Just hard for me to give a straight answer online without the bike next to me unless its a common issue we’re already familiar with , unless otherwise in the end, all the checking you did , probably will turn out to be a bike just needing a new part or you missed a small simple thing such as corroded plugs (strip it all down and clean every plug you can find) , unlike Carb Models, the EFI system also checks “resistance” to certain sensors. So if the resistance is too low or too high , it is usually caused by an oxidized / rusted plug that needs cleaning out instead of the actual sensor being fault.
Ie. Tank Level Sensor plug says “100 ohms” , it has a yellow wire (the black one is for ground usually) , if i see the same yellow wire at the dashboard connector , it says 150ohms , i think i have an issue along the wires that rose the resistance quite significantly possibly a bad kink or exposed wire rusting or connector at the dash has water invasion (if its not waterproofed) etc…. Assume that an object attached to the engine has high resistance but the ECU is expecting it to be low when it calls it , it will go haywire sometimes when running , as it’s not getting the values it wants. Hence Simon and Myself in this site usually repeat to owners to try to ensure the harness is as pristine as possible before replacing faulty sensors on EFi bikes. Resistance that is too high on Stators will burn regulators , slowly cook everything that’s connected to the harness unless the fuse blows first, the ECU won’t behave the same anymore, but since you have a DELPHi unit (hopefully, not the 2018 MOTO1 ECU) it “may” or “may not” warn you with an error code at the start “Battery Voltage too high” etc…
I digressed a little!
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