exhaust popping sound

[joekp17]

Hi everyone, i have a 2008 roketa sicily 150 and i recently adjusted the valves (intake to .003 and exhuast to .005). i also cleaned out the carb and replaced fuel lines. After doing this, my exhaust makes a popping sound when decelerating. Any ideas how to fix it? Anything would be appreciated thanks!

[bull]

Your symptoms indicate that it is running rich. Recheck your carb work and adjustment / settings.

[kz1000st]

I would also make sure the exhaust pipe isn't leaking somewhere. Popping is also a sign of cold air getting the pipe.

[joekp17]

Thanks for the replies, i will try to lean it out. Could it be something with the vacuum in the carb? Because if i decelerate slowly, i dont hear the popping sound.

[kz1000st]

Somebody bail me out here. There's a diaphragm thingy on the side of the carb that meters fuel during de-acceleration. I had it go bad on my 650 Kawasaki and it made horrific pops under closed throttle. Do these things have them?

[joekp17]

There is a diaphragm in it that controls the needle position.

[kz1000st]

I just looked at a carburetor picture on Parts for Scooters. On the side opposite the electric choke there is a round cover with a hose. That would be what the British called the "anti gulp valve".

[joekp17]

So how would you go about fixing that? I took it off anf there is a small diaphragm with a spring. I cleaned it with carb cleaner so hopefully that does the trick!

[rks]

Check the vacuum line that runs to the right side of your carb. Sounds as if it might be dry rotted, cracked, leaking. This line usually runs from a T on the left side of carb, up over the top, to the right side, connecting to the ACV valve. A vacuum leak will render the valve inoperative.

"ACV Valve: This has a small diaphragm which moves when the throttle is snapped shut to keep the exhaust from popping or backfiring."

[kz1000st]

"ACV Valve: This has a small diaphragm which moves when the throttle is snapped shut to keep the exhaust from popping or backfiring."

Thanks. I knew it had a name but I couldn't think of it.

[joekp17]

thanks! Ill check for a leak later today

[joekp17]

So i checked the hoses and there are no leaks, however when i was checking for an exhaust leak, i found a hose that sucks in air. Its just open. It comes from the emissions canister (i think that's what its called?) Or the pair system? I found if i cover the hole, my engine makes less noise and there is no popping on deceleration. Should i put a plug on this hose? Or what is it supposed to connect to?

[rks]

It used to connect to the air box (where the air filter lives). A large number of owners have removed all of that stuff. There are block off plates available, from any number of sources, to do exactly what you are asking about. Here is one source...http://www.ebay.com/itm/like/390924476620?lpid=82&chn=ps

Or, one can be easily made. I used a hacksaw, a piece of the angle iron from the cage the scooter arrived in, a drill, and a grinder.

[joekp17]

Thanks so much for all the help! My scooter is finally running good again and i can get out and ride!

[kz1000st]

All part of the friendly service. Ride well and be careful.