"Engine Blueprinting"


The Engine Analysis Program

Part 5sprkplug.gif - 1.27 K


Now that you have all the correct timing and compression ratio set, it is time for final assembly. Take ALL the parts of the engine to the kitchen sink and with a toothbrush, SCRUB everything at least 3 times with dish washing detergent. Rinse very well and allow to dry. Now with everything spotless, it is time to install the bearings in the case. Get your crank, flywheel collet, drive nut together in a clean area. Using a propane torch, heat the case/front end until it is very hot. Place the large bearing on the crank and quickly insert into the hot crankcase/front end. Insert the small bearing onto the front of the crank and QUICKLY push it until it stops against the front end. Install the collet, flywheel and snug the nut. The front end should be free and rotate with almost no friction. If it is not COMPLETELY free, that will not be good enough! Allow to cool. Complete the installation of all the parts and after final assembly apply several drops of Midas Touch a Teflon Platelet Mixture from Boca Bearings. This stuff is really the best assembly product I have found. Rotate the engine to see that everything is free.

Initial run-in:

After you have the engine back in your model, it is time to break in the engine. A Boater/Engine Builder (Steve O'Donnell), who I respect a great deal told me some time ago about his break-in procedure. I have been using a variation of it with VERY good results. I remove the water line from the rudder assembly and make sure that I have the needle set on the rich side of perfect. I use a mixture control, so that is easy. For those of you who don't have a mixture control, get to the rich side of a perfect needle. I launch the boat and run around the course, giving the engine full throttle for at least 1/2 of the straightaway and then reducing the throttle to half in the turn (allowing the mixture to richen), then full on 1/2 of the SAW, then reducing to 1/2 in the turn. This "Heat Cycles" the engine and the liner/piston fit will be terrific. I usually run 4-5 tankfuls of fuel through the engine before I ask the engine to "do its thing". DO NOT run the engine very cold, with the water line connected, as it will not break in at all. You MUST heat cycle the engine to break it in!

Another FINE source for any serious 2 cycle engine builder is a book authored by Dr. Gordon Blair, a researcher and one of the foremost 2 cycle experts in the world. This is the ultimate technical guide available.
The Blair book & software can be purchased from SAE (Click Here

ENGINE Analysis Software for the Serious RC Competitor



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