OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Trimmers and Brushcutters Homelite Trimmers & Brushcutters Latest tip find HomeliteST-385 How to tune it?

My latest tip find, this Homelite looked in pretty fair condition still with a spool of line and even the shoulder strap. Cleaned out the mud wasps from the air filter and the muffler and the small breather filter in the fuel cap. Also the foam in the air filter just crumbled away when I touched it so took it out completely for a test fire. Some fresh fuel, 6 pumps of the primer and lo and behold it tried to fire up. A bit of choke and some throttle and away she went but bogged down with choke off and throttle up. Noticed the head wasn't spinning. A bit of a twist of the spool and felt the shaft free up. Started it again and got it to run at about half throttle but it won't take full throttle. So, my question is, how do I tune this one? are these red and white bits shown in the photo anything to do with it and what do they do?
Thanks in advance.

Surprise no one has answered this easily one.

First those are the limiter caps on the fuel mixtures.

As with any new find find or repair of a two cycle that doesn't run well as you describe is to ultrasonic clean the carburetor and install a new rebuild kit. Those fuel mixture screws do need to remove to clean the carburetor properly. Look at the retainer clip and you will find a split that you can put a flat screwdriver into so you can open it up so the limiter caps can be removed and the screws.

After cleaning re install the screws lightly seat them and then back them out 1-1/2 turns each. Then start the trimmer and adjust the L speed first for best idle speed followed by the H speed for best top speed with a slight 4 cycling.

Once you are satisfied with the adjustments then reinstall the limiter caps in their mid range positions.

Thanks for handling that AVB, it had been sitting there for a while, as you said. My own excuse is that I don't answer questions on half-crank engines of any kind, but several other members do, so this one was unlucky I guess.