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Post by coachhejl on Dec 31, 2022 16:09:48 GMT -5
Story made short... My carb on my scooter is not adjustable. The air screw is plugged. The needle is not adjustable. (I did use 3mm washers and shims). So I bought this (below) to gain flexibility as far as adjustments. 50CC Carburetor 4 Stroke GY6 High Performance 139QMB Carburetor for 49cc 50cc Scooter Moped PD18J Carb Engine, 50 cc Carburetor, 50cc Moped Carburetor + Intake Manifold by LOYPP a.co/d/8W6quUcMy old carb had 72 main jet and 35 pilot. This one has 78 main and 33 pilot. Anything past 1/4 throttle it's a dog and boggs down or dies. I even put my 72 jet in it...same thing. So I put the 78 in my old carb and it runs well. It was slightly lean at wot with the 72. Anyways...what could be causing this. I also ran the new one with stock air filter and no air filter. It all pretty much gave the same issue. Any ideas? |
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Post by coachhejl on Dec 31, 2022 16:44:01 GMT -5
 also what is this little tube? My old carb has this welch plugged up. |
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Post by FrankenMech on Dec 31, 2022 19:15:10 GMT -5
Bowl vent.
Is the auto enricher plugged in and working.
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Post by coachhejl on Dec 31, 2022 20:44:03 GMT -5
Pretty sure. I could hear the higher idle when starting cold. Everything is tightened down good. And it's just a clean swap. Maybe it's just the carb in general. Maybe it's bad. Bowl vent. Is the auto enricher plugged in and working. |
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Post by GrumpyUnk on Jan 1, 2023 9:28:37 GMT -5
Is this the essence of the comment:
"Anything past 1/4 throttle it's a dog and boggs down or dies."
If so, check the needle is in position and has not flopped around which could affect fuel flow.
Check that the vacuum operated slide moves freely. Check that when you move the slide up in the venturi you hear a 'whoosh' sound. The vacuum diaphragm on top should be sealed, and as the slide moves it will make noise.
Do you think it is getting too rich/lean, or is it getting choked or limited when you go past 1/4 throttle?
tom
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Post by coachhejl on Jan 1, 2023 12:07:14 GMT -5
Not sure but I can move needle around to see. Is this the essence of the comment: "Anything past 1/4 throttle it's a dog and boggs down or dies." If so, check the needle is in position and has not flopped around which could affect fuel flow. Check that the vacuum operated slide moves freely. Check that when you move the slide up in the venturi you hear a 'whoosh' sound. The vacuum diaphragm on top should be sealed, and as the slide moves it will make noise. Do you think it is getting too rich/lean, or is it getting choked or limited when you go past 1/4 throttle? tom |
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Post by coachhejl on Jan 2, 2023 19:18:56 GMT -5
I did all this and it all checks out. I also tried several different needle positions. It gives me all the same issues. I can put the back tire off the ground and if I open up throttle, it winds up and then immediately boggs down to nothing...if it doesn't die, it'll kinda do the same thing in waves...wind up, and bog down. When it boggs down, itll sometimes die. If I put the old carb back on...it functions normally. Are the carbs ever just...bad? Is this the essence of the comment: "Anything past 1/4 throttle it's a dog and boggs down or dies." If so, check the needle is in position and has not flopped around which could affect fuel flow. Check that the vacuum operated slide moves freely. Check that when you move the slide up in the venturi you hear a 'whoosh' sound. The vacuum diaphragm on top should be sealed, and as the slide moves it will make noise. Do you think it is getting too rich/lean, or is it getting choked or limited when you go past 1/4 throttle? tom |
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Post by aeroxbud on Jan 3, 2023 8:49:59 GMT -5
Yes I made the mistake of buying a cheap carb once. Got it to run, but was never totally happy with it. Even though I spent about ten hours trying everything.
Brought a Dellorto, in twenty minutes, was running fantastic.
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Post by GrumpyUnk on Jan 3, 2023 9:25:07 GMT -5
You can get a defective carb out of the box, or have one that has been allowed to sit with fuel inside. Either can be difficult to get working, if not impossible.
I had one that would take off fine, then start to bog and seem to 'cough' at mid speed and then finally clear up and accelerate as much as the engine would. I did not fix it. I replaced it, and moved on.
I could not find the problem, and figured it was a waste of time. Maybe someday when I have nothing else to do...{not likely while alive}
tom
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