FlyinTiger
Posts: 641
Joined: 1/26/2004 From: Penn Valley,
CA, USA Status: offline
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Anyone that has a 4-stroke for the first time should get with someone that has experience with the brand and size you chose if possible Q1: "i've enlarged the hole on the backplate to make it fit. but my question is this: do i have to do the same thing for the prop or are there props especially made for 4 strokes?" A1: As long as you were very careful enlarging the hole in your spinner everything should be okay...put it on the drill bit you used to drill it out and spin the backplate. If it spins true then everything is alright, if it "wobbles" then you need to get a new backplate. As far as your propeller goes, get a PROP REAMER from your local hobby shop and ream your props by hand...doing it by hand ensures the hole stays in the center. There are props made especially for 4-strokes but you don't want to use them. Stick with the APC 13x4 Wide prop for the .72 engine after breaking it in with the recommended "break-in" prop. Q2: "also the instructions for the engine says to check and adjust the valves/ "tappet" after 1-2 hrs of run time." A2: To check the tappets open the top of the engine...there is a valve cover above the cylinder. You'll see the tappets - these are the things that push on the rocker arms to actuate the valves - and you will be able to see the little screw that allows for adjustment. Use "feeler guages" to set the clearance to the recommended value by adjusting that screw the slightest amount. Basically, when there is no pressure from the camshaft on the pushrods the tappets should be BARELY TOUCHING the rods. You can test for this by rotating the engine until you see both valves are closed (no pressure on the springs/rocker arms) then look closely at the rocker arms, try to wiggle them. It is best to get feeler guages at your local auto parts store, it takes out any of the guest work if you are inexperienced with working on engines. Q3: "the instructions also say that the low end does not need to be adjusted/ b/c its preset from teh factory. is this true? that would make tuning much easier if it's true." A3: Leave the needles set as recommended and you should be fine if the instructions say so. After running the engine for a bit you'll know if it needs some more tuning. Q4: "the way the glow plug is positioned in the engine makes it almost impossible to reach" A4: Another consideration, does your exhaust reach out of the cowling with the motor in the "stock" position? If your exhaust doesn't reach and you can't reach the glow plug, then the easiest thing might be to turn it upside down to make everything easier. If you want to get a "remote glow adapter" order it from www.heliproz.com and make sure you get the one with the rubber boot that secures it to the glow plug. Q5: "as far as breaking it in, do i have to do it exaclty as indicated by the instructions?" Q5: The instructions are written to keep people from burning up the motor...covering their behinds... Definitely take off the cowling and run two tanks through the motor by the method in the instructions. With the cowling off the motor will get plenty of cooling on the ground. Use your "break-in" prop (recommended size in the instructions) for the first gallon of running the engine. This prop will be a little smaller than the one you'll run later and will put less load on the engine during initial break-in. After two tanks of starting it, running it for two minutes, then shutting it down for a minute, etc. you'll be ready to fly. During this time make sure the high end is sufficiently rich for cool running but well below "peak RPM." When you fly your aircraft remember that you are richer than normal and your fuel tank will not last as long as you think. It wouldn't hurt to check your fuel level after flying for only 8 or 9 minutes. Do large lazy manuevers varying the throttle thoughout the flight. Limit your full power uplines to only a couple of seconds and make sure to pull the power back to idle on the down lines for cooling and to keep from over-revving your engine. Good luck and happy flying!
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FlyinTiger
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