Adjusting carb when there's only one screw?

[swinny]

Evening all i've recently purchased a long handle hedge trimmer stihl one, it has a fs85 engine so its obvioursly had an engine change or a new cover on it.... sometimes its slow to pick up... and i've tried adjusting the one carb adjustment screw to no effect.... is there a factory setting for these?

 

i'm going to strip it and clean it all but wanted to set the carb so it picks up nice and crisp

 

cheers chris

[rotax81]

it should have one idle screw and 2 mixture screws.

failing adjustment it may need a new carb kit, even though the old one might look ok.

[swinny]

its got one idel screw and one adjustment screw..... think it may be a strimmer engine on it

 

will double check soon

[spudulike]

FS85 is a brushcutter strimmer, I have serviced an FS80 - only has a single mixture adjuster for the "L" low speed mix - usually set to one turn out or thereabouts.

Set to this and ensure the air filter is clean, if it still sounds flat, it could be a blocked exhaust, carbon in the exhaust port, dirty carb or a poorly adjusted needle valve arm. The single screw carbs are a real pain - they always run rich and no way of adjustment - the manufacturers carry on thinking no one can adjust a carb but them!