Quickie JETT .40
Operating Instructions
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Thank you for ordering the Quickie-Jett Engine from Jett Engineering. We believe that it is the finest, most powerful engine in its class. If you have any questions or comments, please give us a call any time during working hours, 8-5 central time, at 713-680-8113, or visit our web site at jettengineering.com.
PROP: A high performance engine should have a well balanced prop to perform well. Reinforced Nylon, Carbon Fiber or Fiberglass are OK, but use extra care to avoid injury. Pick a prop which turns at least 19000 RPM on the ground to get the best needle valve behavior. We recommend an APC 8.75 x 9W OR 8.8 X 8.5 or 8.75.
PLUG: We get the best RPM from the Nelson HD type plug, but much better behavior using a standard. We recommend K&B 1-L if you have a stock type head. Use a new plug often for best results.
BREAK-IN: There are many theories on break-in. ABC and AAC pistons and liners need very little. However, your rod and other moving parts need to be well seated before they can perform reliably. Piped engines and specifically piped AAC/ABC engines tend to work against you during break-in. To adequately loosen up an AAC/ABC (which has some interference fit) it must be hot. This means running it fast and hard, but you must do that before you break in the rod--Catch-22. This is why almost anything works as well as the next. This is what we do: We run your engine for you and take the first chance. After we start it we heat it up immediately, but not all the way to the peak. We run it rich at about 17500 for about 30 sec. and then we test the peak RPMS. If it runs over 19300 on the 8.75 x 9W APC (15% NITRO) we send it to you.
When you get the engine, open the needle one extra turn and crank it up. At full throttle, lean the engine in until it is staged on the pipe and running about 18500. If it isn't still slightly rich, change to a smaller prop. Let it run there for 15 sec., then lean it in to find the peak. When the engine peaks, immediately open the needle until it slows down to 18000-18500 (about 1000 below peak) and let it run for about 15 min. Now you can go fly.
TANK: A six oz. Bubbleless JETT tank works well for Quickie, but any good clunk is OK if you have no leaks and keep it clean. CLEAN YOUR TANK AND EQUIPMENT OFTEN AND USE A FILTER IN YOUR PUMP. If you mount your engine upright make sure that the needle valve assembly is at least as low as the centerline of the tank (this may be impossible). If not, turn your engine sideways so the engine won't have to draw up hill. If you have engine problems, look at the tank first!!!! This is where we find most problems. ABOUT 80% OF THE TROUBLE CALLS WE GET ARE ULTIMATELY FOUND TO BE TANK PROBLEMS.
The engine should run almost a full tank of fuel on the ground without changing RPM significantly. Look for air bubbles in the fuel line while running with 1/3 full tank. You should have no air in the fuel line. The tank must be perfectly isolated by thick, dense foam, around all sides, and front and back. Take the time to do this, along with making sure you have new, good tubing in and outside the tank, and above all else, no leaks.
ADJUSTING THE NEEDLE VALVE FOR FLYING: Your engine should be set slightly rich as you received it, but open it one more turn just to make sure. Start the engine and make sure you have a good working Tach. HINT Put your finger over the pipe for one second to prime the engine. The engine should be too rich to take off the battery, so start to lean it in (clockwise). The engine should start to move up the stages of the pipe and be running above 16000 quickly. Continue to lean it in slowly until the engine starts to smooth out, but still has the "crackle" of a rich setting. If the prop is right it will now be turning at least 17500. As you continue to get leaner the engine will seem to have a second wind above 18000 and climb easily to 19000 and hold. If you have difficulty getting more RPM and the engine sags before you get to 19000, try a different prop, with possibly 1/2 inch lower pitch.
Your engine was tested at the factory and should easily reach the RPM levels indicated. If not, please give us a call and we will be glad to lend a hand.
After getting the right prop, open the needle valve a turn, start it up and slowly lean in the engine until the peak RPM is found. Expect the engine to smooth out, then slowly sag as it gets lean and overheats, quickly open the needle 1/2 turn and let the engine cool. Now you know where the peak is, always stay on the rich side of the peak. A good way to tell if your needle is slightly rich is to pinch the fuel line quickly after you have it set. If it doesn't surge in RPM, it is probably too lean.
FLYING: Start off by finding the peak and then backing down about 700-1000 RPM to the rich side for the first flight. We recommend that you use a slightly smaller prop for a few flights (20000-20500 RPM). The engine should run rich in the air and land with a wet, shiny-to light amber glow plug, rather than with a dry, powdery, dark finish (lean). If the engine is too rich it may die suddenly. This may also happen when too lean, but the difference can easily be seen by the flight speed: If it is going very fast and suddenly dies in a turn, it's probably too lean. Hint: These engines are cold natured and may die if you disconnect the battery before the engine is warm. Try pinching the fuel line a few times to warm up the engine before disconnecting the battery. If it still dies, lean in the needle about 1/8 turn and try again. Don't move the needle over 1/2 turn leaner from the hot setting found using the procedure outlined above. Try a new plug and reset the needle from the hot peak and start over if the problem persists.
MAINTENANCE: Your engine is designed to last for many races, but care must be taken to avoid lean runs. A few laps lean will take away hours of life. If you are getting good solid runs and you are never blowing a glow plug, you may be able to lower your head some. Your engine comes with several .002 shims. Carefully remove one and try it again. Use care in removing and tightening the head. We suggest you have someone help you if you are inexperienced. An improperly torqued head will ruin you piston and liner fit in just a few seconds running.
Use a good after-run oil the protect your bearings. We use Marvel Air Tool oil, found at machine tool stores.
Your muffler has stainless steel screws on purpose. They break when you crash and will do less damage to the engine and muffler. Your muffler is assembled with a special high temp adhesive, so if you need to reassemble it for any reason, return it to the factory, or use "red" Loctite from the auto store. (The red will only work for emergency repairs)
Proper installation of internal engine parts is important, so we recommend you let us do that. If not, we will be glad to assist you in any way.
We hope you enjoy your new Jett engine. If you have any questions, call us at (713) 680-8113. HAPPY FLYING!!!
