vacationer
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Post by vacationer on Jun 23, 2021 14:53:33 GMT -5
So I'm starting to think this carburetor doesn't have a mixture screw. I can't find any pictures online of this exact carburetor where I can see every side - just all the sides except the one I need. Here's a photo of mine and the spot where I would expect it to be based on photos of similar carbs:  Here's a link on amazon to the carburetor if you want more angles: www.amazon.com/139QMB-Carburetor-Scooter-Manifold-TOPEMAI/dp/B07GKH148P/ref=sr_1_5?dchild=1&keywords=tao+tao+atm50+carburetor&qid=1624477628&sr=8-5What it does have is an idle speed screw on top of the brass throttle contraption on the side. BONUS: I'm not totally sure of the differences in purpose between... 1) the aforementioned speed screw 2) the two large nuts that can be adjusted just upstream from there on the throttle cable (still right on the side of the carb) 3) the adjustment featuring the smaller nut and the long tube-like nut right underneath the handlebar, and 4) the nut that tightens up on the bottom of the switch casing where the throttle cable connects to the grip (although this one in particular is probably not meant to be a throttle adjustment of any kind). |
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claydoh
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Posts: 172
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Post by claydoh on Jun 23, 2021 19:18:30 GMT -5
It does, it is just plugged. The silver disk below and slightly to the left of the brass (or solver) colored cap thing in your photo. The bowl also has its screw heads broken off, making jet changes equally fun. That plug can be carefully drilled out. 2) Tension adjustment on the throttle cable. 3)Same as 2) but easier to get at  4) I think what you are seeing is a stop nut to keep that throttle cable elbow thingy from moving or becoming unscrewed. |
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Post by FrankenMech on Jun 23, 2021 21:13:55 GMT -5
Or just leave it alone and buy a new carb. Buy a 'stock replacement' carb for use with a stock airbox, you will still have to do some tuning. Buy a 'performance' carb that comes with a cone filter, use that cone filter and maybe do some tuning.
-Don't try to use a stock carb with a cone filter, major tuning is required.
Carb tuning may be above your mechanical skills. An experienced tuner may be required.
There are two idle adjustment screws, one for idle mixture on the carb, and the other is a 'stop' for the throttle mechanism cable 'thingy' on the carb.
The other nuts on the cable are for slack adjustment and locknuts.
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Post by scooter7878 on Jun 23, 2021 23:44:05 GMT -5
Like said above just buy a carb there cheap enough if leaving everything stock buy a stock carb if wanting a performance air filter and a tad more performance buy a 20mm performance carb preferred one that specified with upgraded jets so ur tuning will be minimal. what ever u do be sure not to run lean as that blows cylinders
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Post by FrankenMech on Jun 24, 2021 21:15:59 GMT -5
BTW, That carb you referenced in the link is more like a 15-16mm carb that has been machined out to 18mm.
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vacationer
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Post by vacationer on Jun 27, 2021 12:15:15 GMT -5
FrankenMech all I know about it is that the one I'm working with, which is stock, looks identical to that one. So I managed to the seal off, but the mixture screw doesn't look as expected. Is there a tool for this?? Also there was what I assume to be gasoline on the inside around the "screw". Not sure is that's bad. 
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Post by scooter7878 on Jun 27, 2021 12:34:54 GMT -5
I'm now 100 percent sure bc I always replace the stock carbs but I belive u probably have to remove that brass thing from the hole and u can buy a mixture screw to put there but I could be wrong but man honestly the amount of work it takes to remove that cap and remove that piece than buy a screw and also u than going to have to drill out the bowl so u can replace or clean the jets it dosen't seem worth it to me u can buy a 20mm carb that comes with adjustable mixture screw and has upgraded jets and a removable bowl for 30 bucks Amazon prime u can have it next day
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vacationer
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Post by vacationer on Jun 27, 2021 12:46:13 GMT -5
Well I've got the bowl open already. I've also got a useless spare carb that's another model altogether. Is it possible the screw on this one will fit? If so, I'm willing try and go the distance here before I spend any money.
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Post by scooter7878 on Jun 27, 2021 16:08:28 GMT -5
If the extra carb has a screw it should fit the org one I'm just not exactly sure what u gotta do with that piece in org carb I know for sure there is a way to put a screw in a sealed carb just not sure exact details but if both carbs are the same just put jets into the extra one that already has the screw
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Post by scooter7878 on Jun 27, 2021 16:15:10 GMT -5
From what I can see that's either the screw and it just dosen't have a slot for screwdriver have u tried turning that piece? With small pliers or cut a notch and screwdriver from what I see on YouTube everyone says just remove plug and screw is there
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Post by mikehailwood on Jun 27, 2021 22:29:51 GMT -5
FrankenMech all I know about it is that the one I'm working with, which is stock, looks identical to that one. So I managed to the seal off, but the mixture screw doesn't look as expected. Is there a tool for this?? Also there was what I assume to be gasoline on the inside around the "screw". Not sure is that's bad. You need the right size "D"-shaped tool to adjust that screw. They come in different sizes. I bought one which works with a 1/4" drive ratchet. Not sure where I bought mine. It's been a few years. You can probably grind down a screwdriver to fit pretty snugly and back it out. |
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Post by FrankenMech on Jun 28, 2021 4:18:31 GMT -5
I use old broken drill bit shanks to fit the diameter and just grind a flat on them as required.
The 18mm bore they show is MUCH larger than the 'functional' bore at the throttle plate. Look up the thread on fake carbs. |
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vacationer
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Post by vacationer on Jun 28, 2021 14:41:23 GMT -5
FrankenMech checked and looks like this one is the real thing  I ended up using some tweezers to unscrew it and was able to cut a slot in it for a flathead. Problem solved.
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