I can't get the bike to idle at all. How do i fix this? i have tried messing with the idle screw, but it doesnt help.

wind in both screws all the way then out 1 turn. This should be enough to start the bike, remember to use the choke if its cold. When its running you can adjust the air screw to get the fastest revs you can. The idle screw only affects it when its at tickover, adjust to get ideal tickover revs after all other adjustments. But it really needs to be set up with instruments, like a carbtune.

Check there are no air leaks around where the air intake rubbers are at your carburetor. It sounds like your bike is running too lean or weak which means your air/fuel mixture is running on too much air and not enough fuel. This would explain it running smoothly when you put the choke on as the choke "chokes" the majority of the air from the carburetor and allows more fuel to flow through the carburetor creating a richer mixture. There will be a mixture screw somewhere on the carburetor which will allow you to either richen (more fuel and less air) or weaken (more air and less fuel) by turning the screw either in or out. Only adjust this by a small amount (about a quarter turn at most) at a time and try the bike to see how it rides each time. After adjusting the screw each time let the engine idle for about 30 seconds or so to let it settle to the new mixture setting before riding. There will be another screw on the carburetor which is your "idle" or "tick over"speed adjustment screw which adjusts how high your engine revs while the engine is "ticking over". Turn it in to increase idling speed and out to lower the idling speed. This will probably need adjusting as you change the fuel/air mixture. I hope this helps you and good luck :o)

sounds like air getting into carb where it shouldn't, i.e. vacuum pipe from carb to tank or between carb and engine

there are two screws on the outside of the carb the bigger one with knurling on it is the idle control screw the other one is the air to fuel control screw. It may be necessary to adjust both but try the idle screw first. It may need more adjustments as it warms up. Just mess with it until it idles thr way you want it. Hope this helps.

First and formost make sure air filter is clean.Then start bike and warm up engine.with engine warm adjust idle screw(the big screw with spring around it)Turn clockwise to increase and counterclock wise to decrease.with bike idling properly the low speed air adjustment screw (small screw located just above fuel bowl on side of carb)Adjust in small increments 1/16 turns at a time till bike has smooth throttle responce.This screw contols air flow during idle and up to 1/4 throttle.From 1/4 throttle and up the needle setting on plunger inside of carb takes care of 1/4 and up.You usally dont have to mess with needle unless you do upgrades to get more power out of bike.But over time the low speed settings can change due to wear on idle needle and air needle.So thats why you have to make adjustments.If bike still dosent respond or idle correctly I would purchase carb rebuild kit and your problem will be solved.

first mess with the idle screw and see if that helps. if not please let me know so i can help you solve the problem

Half right, one is the idle the other is the air mixture screw, which really only affects idle mixture. The mixture screw is usually about 1.5-2 turns out from screwing it all the way in. then when the bike is idling it is adjusted by screwing it in a little until it bogs down (rich), then screwing it out a little until the engine revs up and down(lean) and finding a smooth engine speed in the middle.
To initially set the idle, look down the carb throat and screw it in until it just starts to lift the slide.
But this doesnt help the starting problem, there may be a blockage in the carb, or if you have cleaned that already, may have to check further, many of those smaller engines need the suction though the standard air cleaner to run properly

The timing is factory set and doesnt change, does it have the idle screw? I assume the one you adjusted is the air mixture screw at 1.5, you shouldnt adjust with the cable as it might cause the engine to rev on full lock, it needs a small amount of freeplay

No you are confusing the idle screw (a thumb-screw) with the air/mixture screws, these are turned inwards (clockwise) until they lightly seat & then back out the specified amount
You should have the bike tuned by a professional who should include synchronising the carbs, this will let the engine run more smoothly, idle at lower revs ,increase speed & all-round performance speed

Ride safe
Bike-Doc
Please mark this as very helpful (if it has been!!)

hi there, have you cleaned the carb lately? i have a honda anf 125, a tad bigger that a 100. anyways, usually a mis-tuned or dirty carb makes the idle of our bike go crazy. If your a do-it-yourselfer, dismantling the carb and cleaning the jets, air ports, and choke lines would be best. Not to mention replacing the fuel filter if you have one in series with the fuel line. If you have cleaned the carb and installed it back to the bike, tuning is next. don't worry if you don't know the right position of the air-fuel screw w/c is next to the idle screw. Turn the air-fuel screw clockwise until it stops. Remember the position of the screw. Turn the idle screw clockwise a few turns until you see the throttle piston moves upward a bit. Then, start the bike. Turn the idle screw until the bike is running without stalling(higher than idle rpm. just like the bike is cruising about 40kph) . Now its time for the tuning. Turn the air-fuel screw counter-clockwise count your turns while listening to the sound of the engine. You will will hear the engine runs smoother and the the rpm starts getting higher also. Stop when you do not hear anymore significant change. Then turn the air-fuel screw clockwise a little about 1/8 turn then stop. Slowly turn the idle screw counter clockwise until you reach 1200 or 1400 rpm (well thats the standard value). Now, try revving the engine, if the engine looses power at the high rpm, turn the air-fuel screw 1/8 clockwise more. Do this step until the pooot-pooting stops. Try the bike and feel the power. If it feels the bike is back in shape. try using the bike for a few weeks. After a week, remove the spark plug and look at the tip. If the tip of your spark plug is kinda grayish or slightly redish(depends on the type of petrol you're using). You're setting is good to go. If the tip color is dark gray to black, the setting is to rich. turn the air-fuel screw counterclockwise about 1/8 turn, then test again. if no color change occurs well the engine should be checked and that's another story.

Hope this helps. More power!