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Discussion Starter #1
ive just purchased a ktm 125sx 2003 model and im have=ing problems with the carb and main jet, the petrol is flowing out of the overflow pipe,do i need to change the carb and main jet. it has been cleaned but the problem is still there? what is the standard main jet size and should i get new carb any hep thanks shaun!!!!
 

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Definitely sounds like float problem. Remove carb, remove float bowl, remove float (don't lose the pin that holds it in place), and remove the float needle valve (don't lost that either). If bike has been sat for some length of time you'll be quite likely to find that there is a varnish-like residue in the float valve seat area and on the float needle. Clean this off with plenty of carb cleaner and tissue paper/cotton bud or similar. Spray carb cleaner in the spring loaded pin on the float needle (crap can cause the spring in there to stick). Blast carb cleaner into the fuel inlet on the carb to clear crap out from behind the valve seat. give it a good poke around.

Then reassemble carb, check float height. It's ok to set it slightly lower than the book recommends - ideal if carb overflows when bike tipped 40 degrees or on its side. I check this by refitting the fuel supply pipe, holding the carb upright in the position it would be in if the bike were standing up, turn on fuel then tip the carb over as if bike leaning at 40 degrees, and making sure fuel spills out then (have plenty of tissue or rags to soak up spilled fuel, and do it outdoors without smoking). Once happy with float height, turn off fuel tap, drain carb, smear a little oil in the carb boots to make refitting easier, and bung it all back together. Should be good to go.
 

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Discussion Starter #6
so no nned to buy new carb then? what size jets should use as been told they need changing thank for the reply!!
 
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