Backfire after I let off the Throttle By zombieninja (Read 10,563 times)

[jvino]

Glad you got that pop under control keep up the great work.

[zombieninja]

OK, so I noticed I was leaking a little gas from the fuel filter. No big deal. It was the crappy line the carb came with. I figured newer=better. I was wrong. Switched it back to the old line. Works fine now. No leaks.

OK so here is the interesting part, while I had my seat off, I figured I would check the other lines. Well when I did I noticed that the line from the "PAAR" system or whatever it is had disconnected from the valve cover. Its the big line that connects understand the S line thing. Its a vacuum line but a big one. So I reconnected the thing. So here is my question. I have no idea how long the line has been disconnected like that. The scoot was running fine except the small backfire. Should I leave it off or keep it plugged in?

[zombieninja]

Here are the pictures. (If I can get em to link correctly)

[jvino]

Sorry I am not sure your going to have to wait for alley or basham. Or some else sorry. Zombie ninja Today is a great day to go riding though.

[Alleyoop]

The FIRST PICTURE is a PAIR system:
Hook up that hose onto that valve. That hose goes to a CANISTER from the canister another hose JUST HANGS LOOSE to suck in AIR. On the canister should be a VACUUM HOSE that goes to the INTAKE MANIFOLD or a "T" or a "Y" connector. The Vacuum line opens the Diapghram in the canister to allow air to be sucked in by the VALVE at the bottom of the VALVE COVER.

The SECOND PICTURE is CORRECT and there should also be a VACUUM HOSE connected to that CANISTER.

Now the TOP CONNECTOR on the VALVE cover is your Valve cover VENT hose, that should either go to the airbox or if loose put a fuel filter on the end of it and ZIP TIE it HIGHER than the valve cover. Reason is so if it squirts out oil from the valve cover it will not get all over your motor and tied up high the oil will drain back down.

THE THIRD PICTURE with the OPEN LINE WHERE is that connected to on the other END?

Alleyoop

[Bashan]

I read every word. The way to learn is just exactly what you did...get in there and take things off and put them back together and keep doing it until you don't have to think about the procedure. Eventually, you think about what's actually going on with the components, not the disassembly or assembly. Alley, JR, and the crew are thinking what's going on inside that puppy...not how to get that carb out of that intake manifold. I do...but they don't.  Alley would confirm if it's running well don't touch the A/F screw. But default is turn it in till it's snug but not too tight. Then 2 and 1/2 out. Is that OK for 50's Alley? I think it is. I'm not great with 50's.

[Bashan]

I just saw you pics. There is some debate on how the PAIR system works. Here's my take. It is totally passive. There are are pressure vacuum pulses from the push of the exhaust stroke. I know that sounds counter intuitive, but think about the ocean. A wave comes in and there's a vacuum that can suck your arse back into the ocean. So for every positive there is a negative. Sorry...I do go on. The negative pressures within the exhaust system pull fresh air through a reed valve just before the exhaust intake of the PAIR system. This air is supposed to help burn unspent gasoline. So, the PAIR system does nothing until air is PULLED into it. I'm not sure it does that and I've did experiments on that. But anyway, that hose leading into the bottom of your valve cover? It's just a passive air intake and has NOTHING to do with the amount of air that goes through the carb or anything else. The ONLY thing you have to worry about is make sure the vac actuator line that runs to the PAIR canister doesn't leak or is closed off. It's all junk. Plug the vac...plug the hose to the reed valve...throw the rest of that crap away.

[Bashan]

OK...I found it...here's how to get rid of the PAIR:

You can make a plate to block off the head but I have successfully stuck a rubber stopper in that tube after cutting it...(sorry Sprocket). Obviously a metal plate with a gasket is best. By the way...PAIR stands for Pulsed Air Injection Reburn. It is not EGR which is Exhaust Gas Reburn (hey Earl!) Rich

[Bashan]

OK...I ran into this too...vapor canister...I really like these graphics....you're welcome Plebes!

I love you guys....you know that.

[jvino]

Good job zombie the old saying if working well leave it alone. I agree with kz if carb is working good don't mess with it could make you have more of a headache.

[zombieninja]

What a wealth of information. Charts, graphs, diagrams. You guys are the best helpy helpertons I have ever come across. I am so glad I joined this message board. You guys are right about the carb for sure. Its running good and I don't want to monkey with it and create headaches. As far as the PAIR system goes, it will be lucky if it survives the summer. I have an urge to go out there right now and tear it out. Maybe we should have a contest. Most inventive way of destroying your PAIR system wins. Not very invironmentaly friendly but a scooter doesn't leave too much of a footprint anyway. Plus I'm pretty sure that disconnected vac line was the whole reason my scoot was backfiring in the first place. I rode it today and it runs like new. Now to change those tires. And brakes. And valve stems. New grips, I need a rear mud fender, some new mirrors, maybe a couple cosmetic upgrades. Scooter work is never done

[jvino]

Sounds good zombie ninja. Keep us posted and someone will point you in the right direction alley and basham really now there stuff.