Spittin and a poppin at WOT By scatterbrained (Read 3,162 times)

[scatterbrained]

this is going to be a long post. This thing was running great when I left Knoxville Tn headed home to Aiken SC. Ran fine for a few days after. Went out the other day to the store and from the time I left the house it started coughing at WOT. It's an Eagle 150 06 model 157QMJ. So I was thinking bad fuel cause I filled it from a gas can when I got home. That gas has been sittin for 2months or so. So I went and got fresh fuel and drained the tank and float bowl. No water in the gas so I said well hell. Pulled the carb and cleaned and inspected it and it's a good thing I did. Some dumb a** was in there before me and used a hard setting sealant on the bowl o-ring and it was chipping off and floating in the bowl. So I said to myself....self you found it. Yay!!! Striped the carb, dunked it and cleaned it up with a wire brush. Re assymbled it and no good. It's still doing it. Next was a valve adjustment at TDC. The exhaust was tight with no lash so I thought I may have found it. Wrong! Got rid of that pos torch spark plug, changed fuel filter and adjusted the mixture screw per Ally's method and specs. To no avail. No vacume leaks that I can find. The diaphragm seems to be pullin the slide up all the way at WOT. At this point I think I will completely rebuild the carb cause it might have a pin hole in the diaphragm. Maybe to much WOT from Tn to SC. 281 miles. Any ideas guys?

[Alleyoop]

I can tell you this, if it makes POPPING SOUNDS at WOT it is TO RICH it is getting to much fuel from someplace. Check your Vacuum Hose coming from the PETCOCK or FUEL PUMP if it is WET from fuel it is sucking extra gas and you need a new one.

The other thing it could be the ENRICHER is staying RETRACTED and allowing extra fuel all through the throttle range.

It is not the diaphgram if it has a hole or rip it would BOG and you would loose TOP END because it would not hold the needle out and drop and you would have the THROTTLE wide open running LEAN with to much air and not enough fuel.
Alleyoop

[scatterbrained]

I think you might have hit the nail on the head. I thought It strange that when I took off the diaphragm cap that the top side of the diaphragm was wet with fuel. That's where I got the pin hole idea from. I'm gonna bypass it and let it gravity feed and plug the vac line and see what happens.

[scatterbrained]

That made a differance for sure. Now I can tune the rest out of it. Thanks Alleyoop!

[Alleyoop]

Great, so from what you did the Vacuum line was sucking fuel from the petcock which means the petcock was bad and allowing fuel to flow through the Vacuum port inside it.
Alleyoop

[Bashan]

A guy asked me to look at his 150cc Eagle a few months ago. So I did and said nice scooter. He then said you're a jerk but can you fix my scooter? He had the same symptoms as your bike and it turned out to be the ACV (air cut valve) diaphragm, not the slide diaphragm, was leaking.

It was popping at WOT and gas was getting on top of the slide diaphragm as well as running down the vacuum line into the intake manifold. The ACV (air cut valve) leans out the mixture when you shut down the throttle to prevent back farting. It does this by reducing the slide diaphragm vacuum which allows it to drop down a little bit. That lowers the needle and leans the mixture. I only go over this for FYI since it looks like smarty pants Alley has everything under control as usual. Due to the pressures of being a moderator on several forums Alley has had to seek counseling:

Alley at the psychologist

I know, I know, it's a stretch as far as a humorous reference but I saw the GIF and couldn't resist. Sorry about the hijack Scatterbrain.

[scatterbrained]

It's still doing it a little but I thought I might tune it out now cause it did make a diff bypassing the pet cock. If I need it where can I get the ACV diaphragm by it self. I already ordered a rebuild kit yesterday that does not have it. Has everything else tho ie. needle and slide, jets, float and needle valve, mixture screw ect...... Thanks guys for all your help!

[scatterbrained]

Not supposed to be fuel on top "outside" of ACV diaphragm right? Then it bleeds to vacume right?

Attachments:

[Bashan]

No! Not that much anyway. I've had them get a little moist on top and still run great but you have a problem there. The slide itself isn't a perfect seal so you'll get gas up through there sometimes and it's not a problem. I mapped out all of the passages in the GY6 carb a year ago but I forget exactly where they all go. Let me find the pics and I'll show you where the gas could be coming from. I'm working on this guys computer right now and listening to Slash. What the hell, I'll see how far multi-tasking can go.

[Alleyoop]

Dec 22, 2013 7:40:12 GMT -6 Bashan said:

A guy asked me to look at his 150cc Eagle a few months ago. So I did and said nice scooter. He then said you're a jerk but can you fix my scooter? He had the same symptoms as your bike and it turned out to be the ACV (air cut valve) diaphragm, not the slide diaphragm, was leaking.

It was popping at WOT and gas was getting on top of the slide diaphragm as well as running down the vacuum line into the intake manifold. The ACV (air cut valve) leans out the mixture when you shut down the throttle to prevent back farting. It does this by reducing the slide diaphragm vacuum which allows it to drop down a little bit. That lowers the needle and leans the mixture. I only go over this for FYI since it looks like smarty pants Alley has everything under control as usual. Due to the pressures of being a moderator on several forums Alley has had to seek counseling:

Alley at the psychologist

I know, I know, it's a stretch as far as a humorous reference but I saw the GIF and couldn't resist. Sorry about the hijack Scatterbrain.

I hate to do this but I have to correct my boss

The ACV valve does not LEAN anything and does not have anything to do with the SLIDE.

By default the ACV Valve is allowing air to pass through it. When your on throttle and let go of the throttle you are rapidly closing the butterfly and at that point the motor will RUN LEAN. What happens with the ACV VALVE the strong SUCTION(VACUUM) created pulls the ACV DIAPHGRAM and shuts off the AIR and ALLOWS FUEL to be sucked out of the bowl so it does not run lean and Backfire when you all of a sudden close the butterfly. Think of it as a small PETCOCK really, only it needs very strong suction to pull the Rubber Diaphgram away from the fuel inlet that by default is SHUT off.
Alleyoop

[Alleyoop]

I have to ask did you change any of the JETS? If so and it is still popping at HIGH RPMS when you have it WIDE OPEN or near WIDE OPEN throttle you can try giving the FUEL RATIO mixture screw 1/2 turn Clockwise and see it that is enough. IF NOT then you need to put in the NEXT samller MAIN JET.
Alleyoop

[tvnacman]

Tvnacman<-----just listening and watching

I suck when it comes to carbs .

[scatterbrained]

Have not changed anything. It's still a stock carb.

[tvnacman]

I don't care for the elcheapo's off ebay . I only sell the keihin's . They cost some more but wirth the extra coin .

John

[scatterbrained]

Let me start by saying thank you to Alleyoop, Bashan and Tvnacman for all the support. Now I'm sure that it's a fuel problem or a vacume leak. Now I'll say that everything is stock but the stator upgrade I got from Tvnacman and that went off like a fox in a hen house. I could not be happier with that! I know that has nothing to do with my problem either. Now a little on me......I have been a mechanic all of my 38 years. I was born in a puddle of grease haha! I am also a nuclear cert. welder so the mechanical aptitude ain't a prob. Now I can't find that ACV diaphragm any where on the net. Does anyone know where to get one by itself? I ordered a carb kit 2 days ago and it will be here on the 27th but I could not find a kit with a ACV diaphragm. The carb is a Dashun #PD24J. I know I can get a carb cheap but it done pissed me off and if she wants to act like one then I will treat her like one!