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Carb/throttle help

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I'm putting back together the carburetor on a chinese 110 engine. It's a thumb throttle and worked fine before, except getting stuck because the top where the throttle connects came unscrewed. Anyways I put it all back together right and when I connected the throttle and pulled it to make sure it was right it did nothing until the last half inch or so of motion where it grabbed. Basically nothing happens for the first three quarters of the throttle but then the last bit it goes from fully closed to fully open in small press. Before the whole throttle was usable if that makes sense at all. I'm looking in the carb from the intake and nothing happens until I'm almost at full throttle and then the needle lifts up slightly. How can I fix this? Also I'm not sure how far the needle is supposed to go up but even if I disconnect the throttle an just pull on the cable I only have to pull it about a half inch or less before it's fully open. If I shorten the cable so it will pull at the beginning the throttle will only go about an inch forward and then it's wide open I can't push it as far as it's suppose to go. I can post pics if that will help

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Sounds like the throttle cable length in not rigged properly. Does the thumb throttle cam have more than 1 hole option for insertion of the cable end? If so, make sure you put it in the right hole.

How does the cable end connect to the carb slide? Be sure you got it right.

When rigging the cable, there's usually an adjustment turnbuckle at one or both ends, throttle and/or carb. The inner cable is always longer than the outter sheath. The adjuster turnbuckles have the effect of making the outter sheath longer to take up slack in the inner cable, once its connected at both ends. Example, unscrewing the sheath turnbuckle out of the thumb throttle takes up cable slack.

Be sure this is not your problem.

Edited by Trailryder42

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Sounds like the throttle cable length in not rigged properly. Does the thumb throttle cam have more than 1 hole option for insertion of the cable end? If so, make sure you put it in the right hole.

How does the cable end connect to the carb slide? Be sure you got it right.

When rigging the cable, there's usually an adjustment turnbuckle at one or both ends, throttle and/or carb. The inner cable is always longer than the outter sheath. The adjuster turnbuckles have the effect of making the outter sheath longer to take up slack in the inner cable, once its connected at both ends. Example, unscrewing the sheath turnbuckle out of the thumb throttle takes up cable slack.

Be sure this is not your problem.

The throttle only has one cable and one place for a cable. I've already adjusted the on cable extender and gone as far as I can. As far as I can see there's no adjuster at the carb for the cable. The problem is not that there's slack in the line it's just for some reason that it only takes about an 1/8 push on the throttle to fully open the needle, when it should take te entire throttle the way it used to. And I didn't take apart the throttle body itself until after this problem began, the only thing I did was disconnect it from te carb I clean it.

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I've also tried changing the position of the clip on the needle through all five slots and still the problem persists

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I've also tried changing the position of the clip on the needle through all five slots and still the problem persists

That has nothing to do with the problem.

You have to have changed the throw somehow. Is there any way you could have wrapped the cable around a different diameter of the thumb throttle cam? A larger diameter throttle cam means less throw on the lever to achieve full pull at the carb. So I'd take the thumb throttle apart again and make sure.

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That has nothing to do with the problem.

You have to have changed the throw somehow. Is there any way you could have wrapped the cable around a different diameter of the thumb throttle cam? A larger diameter throttle cam means less throw on the lever to achieve full pull at the carb. So I'd take the thumb throttle apart again and make sure.

Which part is the throttle cam? Here's the inside of the thumb throttle ImageUploadedByThumper Talk1401070794.606751.jpg

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Ok, its not built like I was expecting. I see the pivot point for the thumb lever and the tab that pushes on the metal arm. Be sure part of that tab isn't missing or broken off. The thumb lever pivot doesn't have a another hole it can go into does it. If all components are the same, something is different about the way you're hooking things up.

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Ok, its not built like I was expecting. I see the pivot point for the thumb lever and the tab that pushes on the metal arm. Be sure part of that tab isn't missing or broken off. The thumb lever pivot doesn't have a another hole it can go into does it. If all components are the same, something is different about the way you're hooking things up.

I've never had an issue with a carb before so I don't know much about them. Here's how it's setup, it runs from the throttle into the top of the carb, through a gasket and a spring, and hooks into a cylinder with the needle In it, the spring goes into the cylinder and the whole thing goes into the top of the carb and a cap holds it on. As far as I know I put everything back exactly the way I took it out. Before I took it apart the cap had come off causing the throttle to get stuck and wreck the bike, but I didn't see any visual damage just looked like the cap came un screwed. Thanks for the help, I will try and post a pic of the carb side in the morning

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Sounds like a standard screw top Keihin carb. Is it Keihin or a Chinese carb?

It's a chinese knock off, here's a picImageUploadedByThumper Talk1401124514.428559.jpg

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Is the throttle cable the same one that was on there before, or did you replace it?

I see no cable adjustment at either carb or throttle ends. I guess its in the middle of the cable?

I'm stumped, without actually able to see the system in person, tough to figure out.

Edited by Trailryder42

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Is the throttle cable the same one that was on there before, or did you replace it?

I see no cable adjustment at either carb or throttle ends. I guess its in the middle of the cable?

I'm stumped, without actually able to see the system in person, tough to figure out.

That's what I don't get is I didn't hanged anything, same throttle same cable, there is an adjustment in the middle of The cable but all it does is change how much play there is in the throttle, it still only takes a very small ammount of movement to reach full throttle

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It looks like the thumb lever has a spring return inside the lever housing. When the thumb lever is completely off, closed, is the slide in the carb completely closed/ bottomed?

The only thing I can think of is that you have used the cable length adjustment to length the outer cable sheath so much that the slide is being held partially up. Try using the cable adjustment to shorten the outer cable sheath. That will let the slide drop til it bottoms out in the carb.

Adjust it so there's only about 1/16" play/ movement in the thumb lever before it unseats the slide.

I'd be interested in seeing a picture of how the cable end connects inside the slide.

Edited by Trailryder42

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It looks like the thumb lever has a spring return inside the lever housing. When the thumb lever is completely off, closed, is the slide in the carb completely closed/ bottomed?

The only thing I can think of is that you have used the cable length adjustment to length the outer cable sheath so much that the slide is being held partially up. Try using the cable adjustment to shorten the outer cable sheath. That will let the slide drop til it bottoms out in the carb.

Adjust it so there's only about 1/16" play/ movement in the thumb lever before it unseats the slide.

I'd be interested in seeing a picture of how the cable end connects inside the slide.

The needle is all the way seated when the throttle is not pushed, if I loosen the cable I can see it going past the slide and hanging down into the carb. I will try to take a picture of the slide in a bit

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The needle is all the way seated when the throttle is not pushed, if I loosen the cable I can see it going past the slide and hanging down into the carb. I will try to take a picture of the slide in a bit

Must be an odd set up. Most carbs, you wouldn't see that.

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I apologize for taking so long, was waiting on a replacement phone cause mine was broken. Here's a pic of the slide inside,

ImageUploadedByThumper Talk1401726589.384381.jpg

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The cable goes over the slide and back up into a slot, I there's to much slack it doesn't go back into the slot it hangs down past it

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