Help - my PCX has started farting!

[Inderpland]

My old PCX has started farting. Everything sounds like normal when I apply the throttle/give gas but when I ease up on the throttle it starts sputtering/farting.

Could it be the spark plug or are there other likely culprits?

[Tagged]

You mean afterfire? 
 

 

A common cause of afterfire is from running rich (too much fuel going into cylinders), or faulty ignition possibly a fouled (dirty) spark plug, coil, or plug wire.

[Inderpland]

52 minutes ago, Tagged said:

You mean afterfire? 
 

 

A common cause of afterfire is from running rich (too much fuel going into cylinders), or faulty ignition possibly a fouled (dirty) spark plug, coil, or plug wire.

I was not familiar with the term but after googling it I guess it fits. Been filling 95 gasohol on it the whole time so I guess it probably is the ignition system.

[Moonlover]

Like @tagg said it could be running too rich. A simple fix could be to replace the air filter. When was it last replaced?

 

[Isaanbiker]

The first thing to do is to check your spark plug. A healthy environment creates a whitish to caramel colored spark plug.

 

   If the plug is black it's running too rich. But backfiring is usually caused by too lean settings. 

 

A dirty air filter could also be the problem. It's easy to clean with compressed air. 

 

   But changing your spark plug can't be a mistake. 

 

  

[eisfeld]

Back-fire can happen from both running too lean as well as too rich of a air-fuel-mix. When running too rich, excess unburnt fuel ignites in the exhaust, causing the little explosions that you hear as farts. When running too lean instead the fuel doesn't ignite at all and again ignites in the hot exhaust.

 

It's more likely that your PCX runs too lean. The air filter could be too clogged up or the spark plug could be faulty. I'd look at these two first.

 

Does it happen right away (cold start) or only after a while riding?

[Dumbastheycome]

If normal servicing and a change of  spark plugs does  not  cure it then also consider a  faulty or clogged fuel injector.

[VocalNeal]

OP we don't know how old the bike is or the KMs or how you ride. 

 

Purely from your language (apply, ease) it suggests you ride quite conservatively. 

 

If you don't want to take it to Honda for a "big" (8000 km) service then bung the requisite amount of fuel system cleaner (Tesco, BigC, et al) into the gas tank, then ride around for a few days. Time is the key not the distance. 

Then take it for a long ride, reaching speeds in excess of 80 kph. 

 

If it is still the same then it is off to Honda for a 8000km service.

 

NB. Some engines are very susceptible to valve clearances. Not sure about PCX.

[Inderpland]

Judging by your posts I guess a proper service will fix it. The bike has run 44k km. Had a major service done at 24k so the next big service is due at 48k (changing drive belt, coolant, spark plug, ect, etc.)

Will change spark plug and air filter and see what happens.

[VocalNeal]

If doing it yourself it is easy to change the fuel injector. Once one has one in hand to understand how the wiring and fuel line is connected. 

 

Just a thought but .... hold a currency bill up to the exhaust at idle and see if it gets sucked towards the exhaust as opposed to only being blown away.

 

Unlikely but that is the sign of a worn exhaust valve.

[sherwood]

You could start by checking the exhaust gasket is my 2 baht's worth.

[Boomer6969]

On 2/9/2020 at 1:07 PM, Tagged said:

You mean afterfire? 

Thanks, that's what I'm gonna tell my wife the next time she complains.