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gas is flowing, just installed new carb kit. the only way to start it is to squirt gas into the gas screw and it runs for a bit and dies cant figure it out can anyone help thanks.:smashpc:

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Gas is flowing where? It doesn't sound like it's getting where it needs to. Have you checked your mixture screw setting? Generally speaking, it's about 2 turns out +/- 1/2 turn, depending on model and year. What year and model bike do you have?

Also, when you crack the float bowl drain, does gas come out? That'll tell you if gas is getting to the float bowl, but not if it's going out of the float bowl. What was the bike doing to make you think you needed to take the carb apart?

A little more info might help get you a good answer, but it sounds like you've isolated the problem. Assuming you had the mixture screw set properly and it still won't run, I would probably take the carb off and take it apart enough to blast out the mixture screw circuit with carb cleaner from every way possible. Of course, you might as well double check your work while you've got the carb apart. Verify all the right pieces are installed where they should be.

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I got a 2003 Honda xr-70. And for that screw setting is that for both? When I twist the float bowl drain it drains pretty good. I just got a carborater rebuild kit and installed all the new pieces except for two small little o-rings I can't figure out where they go. And all the pieces are in there except the small o rings

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For your bike, the starting setting for the mixture screw is 1 1/2 turns out from fully (but very lightly) bottomed. As for the throttle stop screw, nothing is specified in the manual and I can't remember where mine is set. Maybe start with one turn in from the point at which the throttle stop screw makes contact with the slide. If everything is working, you should be able to get it to run, even if the throttle stop isn't set correctly, but you will have to give it some throttle to keep it running. Then, adjust the idle from there.

One of those o-rings goes on the float bowl drain screw. It probably was stuck inside the boss when (if) you removed the float bowl drain. The only other o-rings I know of go either on the outlet flange of the carb or the float bowl. Those are fairly large in comparison to the one on the screw.

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i did all that and i had to let sit for a while and started up and rode around for a little bit then seemed like gas in the float bowl ran out and it died... let it sit for a while kicked it fired up rode it for a little died.. over and over it seems like it runs outa gas

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Start looking for a restriction somewhere - petcock, fuel line, carb. Could there be water in the gas? How long has it been in the tank? Did the engine behave like this before the rebuild?

Are you sure it's not getting fuel? Maybe something's getting hot/warm and then causing the engine to die. Then, after it cools for a few minutes, it works again until it gets hot. Try checking for spark right after it dies.

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when i turn the petcock on to the on direction it only squirts out a little gas out the tube. and i tryed taking the bowl of and turnin the gas on and moving the float up but gas still doesnt come out. there is no water in the gas its pretty fresh. its been in the tank about a week. I got this bike from my buddy and it wasnt running before. and i dont get it how could the engine getting hot stop it from working.

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Have you checked the petcock filter screen to see if there's a bunch of junk plugging it up? Just remove it and take a peek.

When the float is up, fuel flow into the carb is supposed to be stopped so that seems to be working OK. When the float is down, fuel flows into the carb.

Regarding the heat, sometimes electrical and electronic components can be affected by heat and stop working. In you case, it still seems like you have a fuel restriction. Just work your way through the fuel system piece by piece and make sure something isn't preventing fuel flow.

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What did the trick? If the strainer screen was plugged up and you cleaned it, some of the dislodged gunk may have ended up back in the carb. You might have to take it apart again and clean it if you can't get it tuned.

Since you got this bike and it wasn't running, it seems to indicate it may not have been too well cared for in its previous life. Make sure you do all the basics before you try tuning it. It won't do any good unless the basics are good. Things like cleaning the air filter and the spark arrestor screen, check/adjust the valves, clean spark plug with the proper gap, etc.

When you put the carb back together, was the needle clip in the third groove from the top? That's the recommended position so I would start your tuning with it there. Make sure the engine is good and warm first. Then, adjust the air screw in small increments until you get the highest idle speed. You might have to use the idle screw to lower the idle. Check the throttle response. Adjust the air screw again in small increments to get good throttle response.

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Also keep in mind that you'll never get tire-burning neck-snapping acceleration from a 17mm carb on a 70cc engine. The little carbs do not have an accelerator pump on them, there will always been a slight hesitation when you wick it from idle to wide open.

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Are you having to adjust the air screw or the idle speed screw? Is the setting changing? There should be a spring on each to keep them from backing out. Does the throttle cable or slide operate smoothly so that the slide returns to the right position?

On my 70, I have to adjust the idle frequently depending on the day. And, as someone else pointed out in a different post, the engine has to be hot to run right. It takes 5 or 10 minutes of riding (not just idling) before the engine will run right so don't make any assessments of performance until the engine is good and hot.

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I need help too. Working on 1978 XR75 that won't start. Gas is filling float bowl but doesn't seem to be gettting where it needs to in carb.

If I spray fuel in carb it will start. It's the original carb that was removed and cleaned.

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I need help too. Working on 1978 XR75 that won't start. Gas is filling float bowl but doesn't seem to be gettting where it needs to in carb.

If I spray fuel in carb it will start. It's the original carb that was removed and cleaned.

Most likely, the pilot jet circuit is clogged, not picking fuel up from the bowl. You need to completely disassemble the carb by removing the jets, the float, float needle, air or fuel screw, idle screw and then thoroughly spray and clean with contact cleaner and use compressed air to blow out all the carb passageways. You should be able to see through the main jet and pilot jet when you're finished. Make sure you also spray the contact cleaner into the hole(s) at the intake end where the air filter attaches, they have to be clear as well.

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Remove the slide and put a washer under the needle. It will stop any bog and give instant power. Works like a charm. My sons honda use to bog at the start of a race and I made this adjustment based on a suggestion from a Honda mechanic it it worked awesome!

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Remove the slide and put a washer under the needle. It will stop any bog and give instant power. Works like a charm. My sons honda use to bog at the start of a race and I made this adjustment based on a suggestion from a Honda mechanic it it worked awesome!

Doesn't that do the same thing as raising the needle a clip position? Or is that about half a clip position?

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