If you own a nitro-powered RC car or truck, sooner or later, you'll have to do some maintenance. This article details the “tough tasks” and the best ways to do each one with the least amount of sweat. With a little practice and patience, you'll do these jobs regularly and make it look easy.
Installing and removing flywheels
Flywheel installation and removal are the most routine jobs required of a nitro racer. If you decide to upgrade an engine, test out a clutch, or remove the crankshaft from your nitro powerplant, you'll have to remove and reinstall the flywheel. Removing the flywheel is simple when you have the right tools. First remove the clutch bell, the clutch and the clutch nut. Next, use an automotive “battery terminal puller” (sold at all auto-parts stores for less than $10), and slip it over the flywheel and crankshaft. Twist the terminal puller's handle until the flywheel pops off, and that's it! You could alternatively use a rubber hammer to tap the flywheel off the crankshaft, but to limit crank and flywheel stress (and to avoid scratching the flywheel), invest in a terminal puller.
To install the flywheel, first slip the tapered collet cone (included with your vehicle) over the crankshaft. Next, slide the flywheel onto the crankshaft, put a drop of thread-lock on the threads, and secure the flywheel by hand with the included flywheel nut. Next, lock the crankshaft to tighten the clutch nut. To do this, you can use OFNA's flywheel wrench, Bruckner's flywheel wrench tool or DuraTrax's crankshaft-locking tool; all are good options. Don't use a piston-locking tool, however, as the forces you exert when you tighten it can easily damage the brass bushings in the connecting rod. Tighten the clutch nut (most require a 10mm socket driver), and you've finished.
Installing 3- and 4-shoe clutches
After you've installed the flywheel, you must install a clutch. You might think that installing a 3- or 4-shoe clutch is tricky, but after you've done it once, you'll be a pro. First, slip the springs into the shoes, and slide the first shoe over any of the metal pegs (making sure the shoes are installed with the trailing edge to the right). The most difficult part of installing the clutch shoe is snapping the spring over the clutch nut; it's difficult to do because of the limited space but relatively easy when you use a small, flat-head screwdriver. Push the clutch shoe down with your thumb while you push downward on the spring with the flat-head driver. You may have to pull the trailing edge of the shoe away from the clutch nut slightly to snap it down completely.
Removing the crankcase bearings
When rebuilding a truly worn-out nitro mill, you may want to replace one or both of the crankcase bearings. After you've removed the carb, piston and sleeve and crankshaft, the only parts that remain are an empty crankcase and the bearings. The engine bearings are press-fit into the crankcase, so to remove them, you'll have to warm the crankcase in an oven to allow it to expand. Heat the oven to approximately 250 to 300 degrees F, and “cook” the engine for 5 or 6 minutes. Once you've heated the crankcase, remove it from the oven (use oven mitts!), and tap the bearings out with the end of a wooden spoon or any other non-metal tool.
Removing a tight piston sleeve and connecting rod
Tolerances between an engine's sleeve and crankcase are super-tight for a reason: any gap between the sleeve and crankcase can cause fuel and air to blow by the ports in the sleeve. When you want to remove the piston sleeve from the engine, this tight fit can cause problems. To minimize the risk of scratching either the piston or the sleeve itself, simply slide a few plastic zip-ties halfway into the exhaust port. Gently turn the flywheel back and forth, and as the piston pushes the zip-ties upward, the sleeve should be dislodged. Be sure your hands and fingers are completely clean, and then grasp the sleeve and pull it out completely.
A tight connecting rod can also be a pain to remove, but luckily, there's an easy method. After you've removed the sleeve from the crankcase, place a few drops of oil on the brass connecting-rod bushing where it is mated with the crankshaft. Cut a short piece of dental floss, then loop it around the conrod. Now gently tug the floss to pull the conrod off the crankshaft, and then carefully pull the entire piston/conrod assembly out of the top of the engine.
Nitro Engine Maintenance Tasks
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20 February 2013
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