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Leonard Dacus · Oct 15, 2011

I need some help with carburator rebuild on my old McCullah. put repair kit in carb. cant get it to run right seem like to much gas flow. anyone know how much travel the needle valve should have. carb. is a walbro 439 diaphram operates needle valve from vaccum intake. any help appreciated

BCnT · Oct 15, 2011

make sure the gasket is on the correct side of the diaphram AND there isn't any trash under the needle.

Phil in Pa · Oct 16, 2011

I have this problem with my 30+ year old Stihl.

I had to slightly bend the plate that drives off the diaphram and moves the needle.

I managed to make it useable, but it's still not right. A bit of a pain to tear down the carb and tweak it multiple times.

I'm afraid it's time for the scrap bin, but I hate to give up the first saw I ever bought.

pat sublett · Oct 16, 2011

You might consider a new Carb. Its is better than you can buy unless a new Stihl.

Duner Wi · Oct 16, 2011

Maybe this will help.
http://tech.flygsw.org/walbro_tuneup.htm

Bryan inIowa · Oct 16, 2011

For some Stihl and other makes ,,a new carb is almost cheaper than a kit . Stihl weed trimmer carbs are only 29 bucks

Alont · Oct 17, 2011

0.06" to 0.07" below the edge of a straightedge placed across the body casting edges.
There are actually two styles of WT carbs, the other style is set flush.

Hope this is what you were asking for?

Post back if you need any more info.

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Leonard Dacus

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BCnT

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Phil in Pa

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pat sublett

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Duner Wi

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Bryan inIowa

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Alont

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