Backfiring through the carb? Please help...

Ok, This has been a great bike, I could keep up with the new bikes on it. But then It started sputtering one day a little bit, and then within a few rides got really bad.

Now, It will start in 1 or 2 kicks everytime, even cold, and even after sitting for a while. And, it will idle just fine. But when I start giving it gas it starts sputtering real bad, and shoots gas and air back out of the carb. Like a reverse backfire almost. I can even ride it and until you hit about half throttle it seems fine. It even has good power in the low RPM's.

Are my intake valves "floating" or sticking open? Or maybe my exaust valves are sticking shut?

Someone told me it was the timing, but then why would it run fine till about 2.5-3.5 grand on the tach?

Please help I really miss my bike....

Edited by Kloque

A reverse backfire?

If it's firing back up thru the intake and out the carb that is a backfire. If it's popping out the tailpipe that's a misfire (or a pop).

Backfires are caused by an over lean mix.

If it's happening at mid-throttle I'd be looking at my needle and main jet. You may have lost your clip and your needle is not coming up with the throttle.

Valves don't float until you reach redline. If your valves are stuck closed your engine wouldn't run. Go to your carb!

Will do! Thanks man, I'll let you know if I figure it out.

I thought backfiring was out the exaust, lol...

ya sounds like a jet issue give them a good clean and go from there.

You know, it might help if you told us what kind of friggin bike you have.

lol, I thought I did.... It's a 91 DR350, Dirt only model.

Maybe its the weather. If you were running a bit lean to begin with on the main, cold weather will lean it more. How long have you had the bike? Altitude change-lower elevation?

Maybe its the weather. If you were running a bit lean to begin with on the main, cold weather will lean it more. How long have you had the bike? Altitude change-lower elevation?

Good to see people thinking, but I've had it about 2 years, and it did good through the summer and winter, and then this happened around the next March. And same town the whole time too.

1. Carb bowl almost full of water.

2. Spark plug almost fouled.

3. Intake valve clearance too tight.

4. Resister in the spark plug boot burned out. I find this on bikes that the carb has been worked on recently. Acts just like a lean midrange carb problem.

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