My sons Husqvarna 50cc 2 stroke stalls out as if it ran out of gas. I must pull fuel line to carb off. you hear a burst of air, then I install hose back on it then starts a few kicks later. bike then runs a few minutes and stalls. a vapor lock problem.............please help

The only basic difference between 2 stroke and 4 stroke fuel is that you add a measured amount of 2 Stroke oil the the fuel. What issues you get will depend on how much 2 stroke fuel you actually ran through the engine. A small amount like 2 or 3 minutes of running time won't do the engine any great harm. You said you replaced the fuel for fresh 4 stroke. Assuming you only ran the engine for a couple of minutes you can safely run the engine AT IDLE to burn off the 2 stroke fuel. It will blow grey/black exhaust for a while but this should thin out and disappear as the 4 stroke fuel gets into the system. Once the exhaust gas clears turn the mower off and give it a full service, Fuel filter, oil filter, air filter and spark plug then you should be good to go.

Your carb is starving gas from your saw. You will have to remove the carb. and take it apart, check the diaphragms for hardening or splitting, clean all passages and screen. There is a lot of small parts that have to be put back together correctly, also the diaphragms and their gaskets have to be installed right.

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Since your Husqvarna is a two stroke engine there is almost certainly a reed valve between the carburetor and the cylinder.

Not really, if the fuel is old or has water in it.

Sound like the new carb diaphragm. May be sucking air.


You covered all the bases, New Fuel lines, Filter and Cleaner

Try restricting the air flow coming in and see if it smouths out.

With todays gasoline it turns to what is called varnish very rapidly and more than likely some of the fuel that set in the carb over those 6 months has turned into a gummy varnish so the carb probably needs cleaned, If it is not to bad you can probably adjust the carb with the air/fuel mixture screws and keep it running well till end of the season, shouldn't take more than 1/8 to 1/4 turn though. I hope this helps

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do a compression check if its under 100 psi could be piston rings are bad or leaking gaskets.

the gas sitting in the carb is "still" 2-stroke...there's a bolt on the bottom of the carb...DON"T remove it, just loosen it til the gas leaks out (about 30 seconds or so)...that is letting the 2-stroke gas out and letting in the right gas...make sure the bolt is snug..NOT TIGHT...and giver a few pulls...no choking is needed since it's already flooded from pulling on it...it'll smoke a bit and run a little rough, until it burns the oil mix residue out of the muffler...Now get a Sharpie & mark the cans... 8^)

The carb jets are clogged and in need of cleaning,when the jet clog,the engine doesn't provide enough suction to pull the gas through the clog,When you cover the breather hole,you force all of the suction from the piston's decompression stroke to the carb which allows it to **** the gas.

So to make a long story short.The carbs internal parts need cleaning.


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check the fuek lines for hole and leaks, check the fuel filter and clean if necessary. remove the carbuerator and inspect the gasket; it should be soft and flexible, if it seems hard or brittle replace it. clean the carb with carb cleaner sray (available at any local auto parts store) and compressed air. make sure you get inside the small fuel rail holes. check the primer bulb for pin holes and seating/sealed properly. if that doesn't work have the carb repaired at a service center or replaced.

Hi again,

Any development(s) with your carbs?