Carburetor ?

[decableguy2000]

Been screwing around with a 371. Pretty sure I narrowed it down to the carburetor. I have several other HD12's that need some love. I put a kit in one, but it won't hold pressure, leaking out the diffuser jet? I tried 3 different needles, and no good. I put the same needles in the original one and it held. What do I need to look at next?

 

[huskihl]

Seat maybe varnished up? Carb cleaner on a q tip and clean the seat

 

[Cigmaker]

You need to show us dumb as* people how you did that. I really need to learn how to rebuild a saw properly.

 

[Chainsaw Jim]

Are you talking about the metering needle seat or the main nozzle check valve? If it's the metering seat and a brand new pin doesn't seal then you can try a tooth pick in a dremel to Polish the edge of the hole. If that's still the leak after proper seal then the spring may be too weak.
The main nozzle is only about 6 bucks if you need to replace that. It can also be reconditioned with hot soapy water rinsing through it to clean out any debris.

 

[decableguy2000]

I tried the metering needle seat. Will try a different sprig in the AM. Never changed a check valve before.

 

[Chainsaw Jim]

You can check the main nozzle check valve without changing it. You should be able to plug the high jet by screwing the needle screw all the way in and vacuum testing the little hole in the pan that lines up with the high screw. I use a piece of clean fuel line about a foot long to see if it has enough vacuum to hold the tip of my tongue since the little tester is not very convenient in most cases.
Some main nozzles are not check valves and do not hold pressure like a few HS carbs with a welch plug and removable screen. Most of those I've seen on Husqvarna saws.
The brass nozzles literally just tap out with a punch and fall loose inside the carb throat. It's easy to make one more strike with the hammer and damage things after it falls so grip the punch firm and tap lightly the last few taps.

 

[decableguy2000]

Found some junk in the needle seat area, it was hold pressure again. Ran the saw in some yellow pine for about a dozen cuts, Now to look at the other 3 or 4 HD12 I've had issues with.