Backfiring though carb and pipes

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I have a 1999 Yamaha 1600 that just started running like crap. It started up fine. Then while riding it started backfiring through the pipes. It would hesitate a little while backfiring. The bike would run a little better at higher rpm but I could still hear a slight backfire through the pipes. I took it home and cut it off. After a few minutes I tried to start it again. On the first crank it sputtered and quit and black smoke blew out of the carb. Any ideas?

[Agpilot]

Check intake manifold for leaks with ether...

[davej]

Also if the AIS has been removed check the vacuum cap on the intake manifold nipple. They only last a year or 2 and crack or fall off causing a big air leak.

[Shores]

If your online name is your email address as it looks, I suggest you get rid of that.

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Good idea Shores. What is an AIS?

[brianmac]

Instead of a vacuum nipple I use fuel injection line , not fuel line. Fuel injection line is tougher. I even use a cutoff galvanized nail or a bolt with threads cut off and a couple of clamps keep it lightweight though, and as short as possible, or, you can make it long and zip tied to something else, but you don't want to vibrate all over the place and tear up your intake manifold like a pendulum

[Father Pobasturd]

Also check for a cracked coasting enrichening cover.

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I've looked over these parts and cleaned the carb. It helped a little bit but I still have a bit of a backfire

[Pterrell1789]

I just went through this myself and I needed to adjust the mixture screw. It's on the bottom rear of the carb as you're looking at it.

[davej]

Good idea Shores. What is an AIS?

The AIS is an Air Injection System that injects air into the exhaust ports to help burn any unburned fuel in the exhaust. It is just emission crap that everyone removes. The AIS will also cause popping on decel especially with aftermarket pipes.

[brianmac]

As you guys know I just got a trike last week. And I had the remove my fifth or six AIS system off of Yamaha
Yamaha. This one has been on for 20 years so I got them loose where they would spin and I shot oil in the cracks, but it wasn't until I shot oil inside of the fittings, then I just popped right out. I'm sure the oil spray inside the fittings seeped into the cracks by wicking or otherwise known as capillary effect. I mean they were dogs they weren't going anywhere except 30° to the left 30° to right once I put that oil on inside up into the tube, they popped right off. I I don't think that's in the our AIS removal procedure file

[davej]

The AIS fittings that I have removed from 1600's I drilled and tapped a hole in the center of the fitting to the thread size on my slide hammer and they come right out with a couple slides of the hammer.

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I will be busy with work until Friday but I will check this out and see how it goes!

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So I checked the spark plugs. They looked a bit crappy so I replaced them. I will see where that gets me tomorrow. Got a buddy that is well versed on the mechanic side of the 1600s so he will take a look tomorrow and see what he can do.

[brianmac]

Black plugs matter. Also worn out or electrodes will definitely affect your snappiness of acceleration

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Ok so I changed the plugs last night and took her out for a ride. Everything is running fine now. I still think I'm running a bit rich on fuel tho.