MAAA Wingspan

26 G’day all, in this edition I will discuss how I overhaul a basic two-stroke glow engine. As we are all in a state of lock down at the moment, I figured there was no better time to do a little maintenance to hit the ground running…. Or should I say the, the sky flying!! Anyhow, let’s get started. I will be disassembling an O.S46 SF, cleaning the various parts, doing an inspection and replacing the bearings if it needs it before reassembling and running the engine. The process that I go through is applicable tomost brand of engines, however, if you are anything likeme, make sure you take your time, and place the parts in stages that you pull it apart. PREPARATION Before beginning any job, you should grab the tools you think you will need and get your work area ready. I like to place a clean towel or some cardboard onmy bench, a towel stops the little bits and pieces rolling around. A selection of Allen keys, screwdrivers, a small pair of pliers, a lead pencil (for marking metal), a puller if you have one, cleaners/brushes/work tray, some paper towels and assembly oil. This is not a job for the good dining table, trust me, I’ve been there and tried that and I wear my scares as a result of it as proof!! DISASSEMBLY Ok, so let’s take this engine apart. However, if this is your first time, I recommend you also keep a pen and paper handy to take some notes that hopefully will helpmake putting things back together much easier. First remove themuffler. If the bolts are stuck, try heating thema little with a soldering iron to soften any stuck oil. Make sure to use the correct size Allen wrench or screwdriver to prevent damaging the screw heads. Next, I removed the carburettor and usually the carb is secured with two screws or a drawbar. Remove the prop nut and washer and set themaside. Most engines today use a split, tapered collet to hold the drive washer in place. The easiest and best way to remove a collet is with a small puller if it’s a little tight. I use a small scribe to lightly mark an X on the rear of the head, the rear face of the connecting rod and the rear side of the top of the piston. These index marks helpme orient the engine components properly during reassembly as I usually forget this. Youmay find the screws securing the backplate or rear cover are packed with dirt or grime. Clean themout with the scribe to allow the Allen wrench or screwdriver tip to engage the screw completely and prevent stripped heads. Again, if the screw is especially tight, try the soldering iron trick- it works! Carefully ease off the backplate and try to prevent the gasket from tearing. I use a small hobby knife to ease the gasket from the case or backplate flange. If you tear the gasket, you will have to purchase a new one or cut one from gasket stock. A leaky backplate will prevent an engine from running well. A well-run engine will generally have a lot of burnt oil and grime caked on the head, which can be difficult to remove. Most modern engines use brass or aluminium gaskets under the head, which can leak if not seated properly. Ease off the head and try to pry the gasket free with the knife or scribe point. If it is damaged, a replacement may be necessary so take care guys. JOE ‘WISE’ WANGID: DISASSEMBLY, BEARING REPLACEMENT & GENERAL CLEANING