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Discussion Starter #1
Hi guys hope everyone’s good, got a 2003 exc 125 which now won’t start bought it couple months ago and all was good, it has a full FMF on it and someone said I should check if it has been up-jetted (which it has) but once I put the carb back together again it won’t start? It has a spark and a brand new air filter so I’m stumped ? and help would be much appreciated, cheers
 

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Pilot jet clear and correct?
Fuel bowl filling?
Fresh fuel?
 

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Discussion Starter #3
As far as I’m aware the pilot jet is clear and yes it’s the correct one and how do you check the float bowl filling? And not fresh fuel no
 

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Open the float bowl drain screw. Does fresh fuel come out? Even two week old fuel can give issues if everything is quite right.

It might be worth removing the plug and cleaning the recess around the insulator with a tooth brush and brake cleaner. It might be fouled.
 

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Let me get this right.... the bike was working ok so you took the carb off, fiddled with it somehow, put it back together and now it won't start? (there's nothing wrong with taking stuff apart to check it etc)

Go back through EVERYTHING you did when you took the carb off and stripped it (and put it back together) cos it'll be something you did.....
 

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Discussion Starter #6
So I’ve just had another play with it and the float wasn’t opening far enough so I’ve adjusted it but still no luck I have also put fresh fuel in now. But when the float bowl if off the float works fine but as soon as it’s back on it’s like something is restricting the floats movement? Is it possible the overflow pipe is bent?
 

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Only if it’s become bent during “maintenance”. It should be perfectly straight?
 

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So when you put the bowl back on it’s holding the float valve closed.
Is it possible to put the float bowl on backwards? I’ve no idea what the 2 stroke carb looks like..
 

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Discussion Starter #9
No it only goes on one way and pindie when you mean “perfectly straight” should the internal pipe be completely vertical or at like roughly 60 degree angle?
 

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The brass tube coming up from the bottom of the float bowl should be vertical from what I remember. Not 60 degrees. If it’s bent then it’ll be trapping the floats and affecting the fuel inlet needle, it’ll then be dry or drowning in fuel and wouldn’t start.

This video of a pwk 38 shows the brass tube straight but angled like you say. Either way (straight or bent) it needs to not contact the floats at all.
 
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