Backfiring Noise from Carburetor Air Intake, in 250cc. By carefulrider (Read 439 times)

[carefulrider]

Greetings All:

Regarding my 2006 model year, JMStar/Jonway VIVA YY250T-2, Flagship style body. 244 cc (copy of Honda CN250, upright or vertically oriented) engine; 10" rear wheel:

I cleaned the carburetor, adjusted the air/fuel mixture screw 2½ turns OUT, & assembled it back on the intake manifold. It started right up & was running smoothly. I had not re-attached the black plastic air filter/cleaner tube to the carburetor air intake. I thought I would need to make further adjustment to the air/fuel mixture.

Suddenly & without warning, a noise similar to backfiring came out of the carburetor air intake. Then it was back to running smoothly. It happened twice.

I have never experienced this symptom, so I have no clue. Any suggestions? Thanks in advance.

[fflintstone]

If you are revving it up when it backfires then it is probably a normal result of the back flow of fuel vapors accumulating in the carb and is not likely to happen when you got it all back together--imo--happy trails,fflintstone

[alleyoop]

Yep the reason it backfired on you is the lack of the AIR FILTER attached and it ran LEAN a few times on you sucked in to much air.
Alleyoop

[carefulrider]

Thanks again, People. Now it's on to coolant flushing.