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got a problem,just put on a uni air filter,bike idles fine.the problem is when revving it to the top of each gear it feels like its missing slighty.i need to know which carb screws to turn to sort this out,anyone got any ideas.pictures would help too as not sure what and where the 3 screws are(eg. idle screw ,air mixture screw and fuel screw)

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its a 125 engine,not sure on carb but,one screw by itself on the bottom of carb,another screw on side of carb with a spring on and one more near enough screwed flush next to the one with the spring.any ideas?

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You need to swap the main jet to tune that out of it. I'm guessing because of the new filter you're getting a lean pop. Get it warm, find some place you can hang it out in 4th, wind it up and when it starts to pop, pull the clutch, hit the kill switch, and coast to a stop. You'll probably find the plug is white, indicating too lean on the main.

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i had the plug out tonight and it looks maybe like its a bit rich,fairly black,should i try to lean it abit?if so what screw would it be

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In that case go DOWN a main jet size. The screws only affect operation at idle, not when you're on the throttle, so they can't help you.

I'd do a plug chop just to be sure. You could be fat on bottom but lean on top, a plug chop will tell you one way or another.

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You need to swap the main jet to tune that out of it. I'm guessing because of the new filter you're getting a lean pop. Get it warm, find some place you can hang it out in 4th, wind it up and when it starts to pop, pull the clutch, hit the kill switch, and coast to a stop. You'll probably find the plug is white, indicating too lean on the main.

A properly jetted fourstroke shows a spark plug that looks like it just came out of the box.

You cant read the plug if youre running pump gas. Its got way too much eroneous shit in it. By the time you get the plug to read right, you'll be way lean and it'll run like shit.

If youre running a two stroke, you can read the plug to a certain extent, get it close and then get it the rest of the way by feel.

Usually on pump gas, you end up with the center electrode clean and the plug shell showing carbon ash...If youve got color on the center electrode of the plug youre pissing HP down the toilet..or out the exhaust...how ever you want to put it...

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In that case go DOWN a main jet size. The screws only affect operation at idle, not when you're on the throttle, so they can't help you.

Actually, the air screw affects idle to 1/4 throttle from what I've always read and been told. If you can't get an off idle stumble out with 1 to 2 and 1/2 turns out, then it's time to change the pilot jet.

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sorry guys.bit lost now.all this hastle just cuz i changed the filter?what should i do then?is all this information that you are giving me easy to do as this is all new to me?

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changing jets is easy , Finding one that fits your carb isnt, What sort of filter was on the bike before you swapped it , Have a look at the carb to see if there are any names printed on it :thumbsup:

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