Husky 550xp walbro AT12 carb

[russ t]

Just aquired 2 x 550 xp's, a 2014 and 2016, I'm not offay with these auto tune carbs ..... so could someone enlighten me as to their quirks. started a strip down on the none runner, everything seems to be pointing towards the carb,  tried to hunt down at least a carb repair kit to change diaphram/seals  etc (walbro AT 12 612) or what carb (updated) can be fitted, with no joy, any info seems to be sketchy.  On these earlier saw's were there any issues with the carbs ? can the chips be reset (Husky magic box hook up)? If the saw can't run in idle I assume that that manual reset can't be done ?

 

[adw]

The first thing to remember is if there is any loss off compression the first thing you lose is the idle, so ring or piston wear, yes you can reset the auto tune with the correct lead and the CST box and software, Orange frame air filters are a nightmare for blocking too easily so split and clean thoroughly, the carb itself is pretty standard so usual clean and diaphragms if required, the auto tune unit again is very reliable, but would have to be plugged in to check, this would also give you fuel settings which can help to diagnose so issues by how rich or lean it is running.

A pressure/ vac test is also a good idea.    

[spudulike]

As ADW said. In my experience, older machines like yours often suffer loss of compression so the feel of the compression on the starter handle is first thing to gauge. If poor then check out the piston, rings bore....probably a new piston will bring it back if it is bad but make sure the bore is in good shape.

If you haven't got the CST then treat the saw like a normal non AT machine and you may well find the issue.

On the carb...check the gauze strainer, the pump diaphragm and also check the metering diaphragm isn't bagged out of shape.