Carb overflow



  • Waiting for the decals for my 89 I thought I would ultrasonic clean the carb on my 125 dt mx (same as on the early dt125r's) came up well and checked float heights etc. Reassembled and petrol poured out of the overflow, stripped and checked multiple times and kept happening. Left bowl off and closed floats with finger and all fine??? Checked float bowl gasket was not causing any problem (replacement, slight difference, ) all fine. Filled float bowl with fuel and pouring out of overflow even when half full , examined overflow pipe in bowl and hairline crack along its length. Took photo but hard to see, not new or caused by ultrasonic bath I think, metal oxidized in crack. Assume it was gummed up and cleaning removed fuel gum, how unusual is that?? So beware if you come across same problem.0_1518193290091_20180209_161042-576x1024.jpg



  • This is the after picture, used acid flux to clean crack, then soldered with soldering iron and all seems ok, fingers crossed. Not the neatest job but dont want to disturb pipe in carb body.
    0_1518195645326_20180209_165426-576x1024.jpg



  • Theres just about only 2 things that can make it overflow.

    1. Floatheight. If its too high, the carb will overflow before the float makes the needlevalve shut of.
    2. Needle valve/seat. If one is worn, or the oring sealing the needleseat to the carb body is worn, fuel will still leak eventhough the float is adjusted properly.


  • @jens-eskildsen said in Carb overflow:

    Theres just about only 2 things that can make it overflow.

    1. Floatheight. If its too high, the carb will overflow before the float makes the needlevalve shut of.
    2. Needle valve/seat. If one is worn, or the oring sealing the needleseat to the carb body is worn, fuel will still leak eventhough the float is adjusted properly.

    Or there is a split in the overflow pipe



  • I was going to say can't it be repaired. But you reckon you got it fixed?



  • All done, fitted back to bike and no more overflow. Just surprised as unexpected failure, not seen anything similar before, but you learn something new every day



  • Pics didnt load for me.
    Yeah, thats a very uncommon thing to happen, solder should work just fine.



  • Pictures are fine my end.


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