|
|
Post by steve on Aug 29, 2015 15:45:51 GMT -5
I bought a 20mm Carb to replace my old 20mm carb. The new one has the normal gas input, the bowl drain hose, and the overflow vent. There is a 3rd hose coming off of it. It is right under the throttle, and has a  ' bent nipple on it. When I blow into it, the air comes out of a hole in the output side of the venturi that hooks into the intake manifold. I cannot get my scoot to run properly with this carb. I have it hooked up like a normal 50cc carb, with the gas hooked up in the normal place, but when I take off under WOT, it will take off normal up to 10-15mph, then will start sputtering. Almost like the needle is not rising. Anybody know how to hook up that 3rd hose. I put the same jets in my other carb, and it ran fine, so it's not the jets, unless there is something else at play. Thank you. |
|
|
|
Post by horace on Aug 29, 2015 17:48:13 GMT -5
From what you have described, I can only assume it is a vacuum line of some type. ( emissions possibly ) Do you own a camera? A few pictures could help speed up the diagnosis without going through the guess work. Just a shot in the dark guess----- Try simply capping off that "unknown" line. Then go for a ride.... see what happens. Side note---- There should normally be a hose on the carb not connected to anything... ( overflow/ventilation ) maybe 2 inches long with a degree bend.... this is normal and should not be blocked. GOOD LUCK!!!!! |
|
|
|
Post by steve on Aug 29, 2015 19:31:32 GMT -5
Yeah, I didn't count the overflow, short hose. That one is as it normally is, as well.
I capped it. Hooked it up to the nipple on the intake manifold. Nothing worked.
When it arrived, they had the bowl drain hose looped and attached to the fuel intake. But, that's not right, is it? Can't be.
I'll get some pics.
|
|
|
|
Post by steve on Aug 29, 2015 19:39:59 GMT -5
What is the vacuum line on a 50cc carb? Normal 50cc carbs don't have vacuum lines. In this pic, I am pointing to the mystery line.  |
|
|
|
Post by scooter on Aug 29, 2015 19:43:02 GMT -5
Usually, coming from the carb, there are the vacuum line, the fuel line, the vent tube, and maybe a bowl drain tube. As long as the fuel line and vacuum line are hooked up, the scooter should run. In some cases there will be a vacuum line that is looped from the top of the carb down to the side of the carb, so that's 3 hose nipples. This allows one vacuum hose to feed both the big diaphragm and a smaller one that operates the idle circuit or something. i26.tinypic.com/352182h.jpg |
|
|
|
Post by steve on Aug 29, 2015 19:57:03 GMT -5
I see what you are talking about now. 50cc carbs don't have a vacuum hose that operates the large diaphram. It is raised just by the vacuum that arises from opening the butterfly.
|
|
|
|
Post by scooter on Aug 29, 2015 20:29:19 GMT -5
I see what you are talking about now. 50cc carbs don't have a vacuum hose that operates the large diaphram. It is raised just by the vacuum that arises from opening the butterfly. If that's the case then I'm guessing the line in your picture is the fuel inlet. I assume you have hoses going from the intake manifold nipple to the PAIR system, or you have it capped off if you don't need any vacuum lines. |
|
|
|
Post by steve on Aug 29, 2015 20:44:40 GMT -5
I see what you are talking about now. 50cc carbs don't have a vacuum hose that operates the large diaphram. It is raised just by the vacuum that arises from opening the butterfly. If that's the case then I'm guessing the line in your picture is the fuel inlet. I assume you have hoses going from the intake manifold nipple to the PAIR system, or you have it capped off if you don't need any vacuum lines. The fuel inlet nipple is in it's normal place. I am using the manifold nipple for a carbon canister to vent the gas tank. I have another one capped off. I was really hoping to use this carb. ugh. This carb came from that starrider guy on ebay in NC that has stuff for cheap. It may be junk. My old one works fine, I just had to replace the float, as it got stuck open, but hopefully it won't happen again. |
|
|
|
Post by scooter on Aug 29, 2015 20:47:09 GMT -5
If that's the case then I'm guessing the line in your picture is the fuel inlet. I assume you have hoses going from the intake manifold nipple to the PAIR system, or you have it capped off if you don't need any vacuum lines. The fuel inlet nipple is in it's normal place. I am using the manifold nipple for a carbon canister to vent the gas tank. I have another one capped off. I was really hoping to use this carb. ugh. This carb came from that starrider guy on ebay in NC that has stuff for cheap. It may be junk. My old one works fine, I just had to replace the float, as it got stuck open, but hopefully it won't happen again. If you could show me all the sides of the carb that have hoses, that would help me rule out what hoses are for what. If you have a model number or something to identify it, I can look online for answers too. |
|
|
|
Post by scooter on Aug 29, 2015 21:22:49 GMT -5
|
|
|
|
Post by steve on Aug 29, 2015 22:11:43 GMT -5
That is exactly like mine. Strange. Thanks, Scooter. I'll cap it.
That begs another question: Why won't my scoot run with that carb? I'm going to mess with it more, and will post what I come up with.
It came with jets that are 5mm thread, and normal carbs are 4mm. But, I unscrewed the entire jet tube, and put it in my other carb, and it fit, and ran fine. Very puzzling. Just under WOT, it will not run right past 15mph. Hmmm....
|
|
|
|
Post by scooter on Aug 29, 2015 22:16:56 GMT -5
That is exactly like mine. Strange. Thanks, Scooter. I'll cap it. That begs another question: Why won't my scoot run with that carb? I'm going to mess with it more, and will post what I come up with. It came with jets that are 5mm thread, and normal carbs are 4mm. But, I unscrewed the entire jet tube, and put it in my other carb, and it fit, and ran fine. Very puzzling. Just under WOT, it will not run right past 15mph. Hmmm.... You're welcome. I added to my post above. I am starting to think it might be an oil inlet, and I would agree with you on capping it off if that's the case. I wouldn't know why it won't run. If a vacuum operated carb did that, I'd assume I had a vacuum leak. |
|
|
|
Post by steve on Aug 30, 2015 7:35:08 GMT -5
|
|
|
|
Post by steve on Aug 30, 2015 9:44:31 GMT -5
UPDATE:
Here's the deal. That carb is junk. The diaphram piece is too large, and fits too tight into the opening in the carb, so the needle jet won't open. It is a different size than the other carb I have. This is the second time I have bought faulty parts from this guy. It's the 02starrider cat that sells stuff for so cheap out of NC. I bought a BBK that failed before. I got this carb because he does ship really fast, and I needed one quickly. What a joke.
I've been telling people not to buy this cheap stuff off of ebay for years. I need to practice what I preach. I thought I was smart, and could correct any minor issues with it, and get something fast and cheap that would work. Nope. I'm dumb. This is the last time. I never get those cheap parts for my customers, because of this very issue. I need to treat my own scoot like I do my customers'.
|
|
|
|
Post by horace on Aug 30, 2015 15:32:34 GMT -5
Just an idea------ Is it possible this is a 2 stroke carb installed on a 4 stroke engine??? That would explain the mystery line and rough running condition..... I maybe WAY off ( again just a guess ) but, this would make sense for the conditions described Good Luck again my friend!!!!!! Is it possible the seller sent the wrong Carb??? Or has know idea what is being sold?  Let us know how it goes!!!... |
|
' bent nipple on it. When I blow into it, the air comes out of a hole in the output side of the venturi that hooks into the intake manifold.
