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TOPIC: Carb Problem

Carb Problem 18 Jun 2017 18:37 #1

  • The Blur
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I rebuilt my 1978 DT175. New rings / piston. I had to go with a new Carb from Amazon, It was a Mikuni carb, and it was "speced" for my year, and engine size. The carb wasn't an exact match to my OEM carb, but it was close. Bike was running great for a month.

Now all the sudden, there is fuel pouring from both vent lines. I mean literally pouring out the bowl vent, and the other vent line. Where are these lines supposed to go ? The bike was running great with the vent lines just hanging loose.

My problem is my son took apart the bike when the motor seized, and I was left with a pile of parts. So when I put it back together, I didn't have pictures, or knew where everything came from. Do these vent lines go somewhere specific? why would fuel just start pouring out of these 2 vent lines ?

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Carb Problem 18 Jun 2017 19:05 #2

  • Giancarlo124
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I think a stuck float can cause fuel to overflow like that, give the bowel a gentle tap with a screwdriver handle and see if that stops the overflow, if not you will need to take apart the carb and fix it manually

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The Oil burners: 1973 DT-250, 1966 YM-1 305, 1966 YSD3, 09' jsw TDi

Carb Problem 18 Jun 2017 19:15 #3

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I didn't really do anything to make it stick. I was messing with the oil pump by holding the throttle all the way open with the engine off. Maybe something hung up while I was checking the pump.. Nothing else happened... I'll check it next weekend.

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Carb Problem 18 Jun 2017 19:17 #4

  • Justind511
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A tiny piece of rust or dirt from the tank can cause the needle to stick open. So it's probably nothing you did. Just take carb off and inspect and clean it and try again. Can use an inline filter to help prevent this
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Carb Problem 18 Jun 2017 19:19 #5

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I do have an inline filter. But all good suggestions for next weekend. The pet cock also leaks. Maybe I'll mess with that too.

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Carb Problem 18 Jun 2017 19:23 #6

  • Giancarlo124
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Fix your leaks if you can, but sometimes the needles and floats just stick, not specifically something you could have done

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The Oil burners: 1973 DT-250, 1966 YM-1 305, 1966 YSD3, 09' jsw TDi

Carb Problem 18 Jun 2017 21:28 #7

  • Mothersbaugh
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Petcock parts available still from Yamaha, and the body and passageways can be cleaned like the carb, in the Berryman's.

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