Unstable rpm and motor shaking

Hello Dears,

I bought sillver wing gt 600cc 2013 with 40,000 kms, my Sw-t has an unstable rpm with shaking in its motor. I cleaned the ifuel injectors, changed the coil, spark plugs and cap but unfortunatly the problem still exists.

Can anyone help me solve this problem as I started to hate my bike and willing to sell it if it’s not solved.

Thank you in advance

Without knowing any more about the genesis of the problem, and assuming that the fuel is not contaminated, I going to hazard a guess and suggest that the Fuel Pressure Regulator might be failing to deliver the correct, um, fuel pressure. 

Tim

Are you sure it is the motor and not the drive belt? does it have a rough idle only while at a standstill?
Have you tried to deglaze the drive belt by squeezing the brakes and accelerating up to around 3500 rpm? once or twice.

Sorry forgot to mention that I changed the drive belt as well,
Yes it has rough idle even while driving.

Someone of my friends was telling me that it may be from the O2 sensor!!! is it possible? as I think the O2 sensor has another symptoms than what's happening on my Swing.

I found this article that might help you.
Symptoms of a Bad or Failing Oxygen Sensor - YourMechanic
https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-oxygen-sensor

Rough engine idle and misfires. As your oxygen sensor is going bad you may notice your vehicle is running rough, misfiring or running irregularly while idling. Since the oxygen sensor output helps control engine timing, combustion intervals, and the air to fuel ratio, a bad sensor can disrupt these engine functions, causing a rough or irregular engine idle

Thanks a lot, will try and reply back to you

Would you please assist on where is the location of the O2 sensor?

Very easy. It is located on the exhaust pipe. It has a wire coming out of it and easy to unscrew.

Thank you very much, today will try to either change or clean the O2 sensor and will keep you update if it was the problem or not.

Hello again, unfortunatly the problem is not solved yet, cleaned the O2 sensor and changed the fuel pressure nozzles as well and the rpm is still unstable and the motor is still shaking

Hi.

I would suggest that you find car repair shop who has Automotive emission exhaust GAS Analyzer.
They analyze scooter exhaust emissions.
Possible causes of the engine fault function are too lean or too rich emission, cylider valves, wrong cyclider pressure. wrong ignition timing, old fuel, wrong fuel pressure, wrong type spark plug. Never use multi-tip spark plug.

Thanks Arskal, this is what I’ll gonna do

I never knew it was posable to clean an O2 sensor.

I saw a video on youtube shows how to clean the O2 sensor and I did the same.

Did you ever do a compression test? 

While it's unlikely given the age of the scoot, it is possible that a valve not seating properly would cause your problem. Seems to me that a compression test is a little less awkward than checking the valve(s) adjustment. But if that test shows poor compression then next step would be to check the valves for proper adjustment.

Also improperly seated exhaust valves will drive that exhaust gas analyzer crazy.

Any signs of coolant in the exhaust or combustion gases in the coolant? That might indicate a bad head gasket or warped cylinder head.

I think this is what I’m gonna do since I’m desperate and have no other choice
Thank you Cosmic_Jumper

I'm still with O2 sensor failing, physically cleaning it will not help if the non-visible bits are failing bud.

it's easier for me to change the O2 sensor than doing the compression test since I change it by myself, will change it and report back to you.
Thank you

If the problem only occurs when the engine is idling or off throttle, then you need to balance the vacuum pressure between the two cylinders. You will need to use a manometer gauge. There are several posts on this forum on how to diy a manometer. My picture album has a pic of my gauge. Good luck!