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Two Stroke Engines Will need CDX Disk 4-1 on day 2.

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Presentation on theme: "Two Stroke Engines Will need CDX Disk 4-1 on day 2."— Presentation transcript:

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2 Two Stroke Engines Will need CDX Disk 4-1 on day 2

3 11/ Stoke Engines Everything a 4 stroke engine does in 2 revolutions a 2 stroke engine does in 1 revolution of the crankshaft

4 11/ Stroke Engines The next page in your notebooks will be “2 stroke engines” page #_________ There will be a “2 Stroke Quiz” _______ Lets start with the names of the parts

5 11/ Stoke Engines part names Piston Cylinder CrankshaftConnecting Rod Still uses a flywheel (not shown) Combustion chamber Intake port Exhaust port Reed valve Transfer port Crankcase

6 11/ Stroke Engines Turn your page over and lets start with the strokes

7 11/20016 Intake/________ Stroke TDC BDC Piston moves from BDC to TDC Air/Fuel/Oil mixture is sucked into crankcase Reed Valve Is sucked open

8 11/20017 Two Stroke Piston BDC to TDC A/F/O mixture sucked into crankcase Four Stroke Piston TDC to BDC A/F mixture sucked into cylinder Compare intake strokes

9 11/20018 Down to bottom of page TDC BDC Piston gets to TDC Air/Fuel/Oil mixture is now trapped in crankcase Reed Valve Shuts

10 11/20019 Crankcase compression (primary compression) TDC BDC Piston moves back To BDC Air/Fuel/Oil mixture is now pressurized in crankcase Reed Valve sealing

11 11/ Crankcase compression Is only a few pounds of pressure per square inch (psi) [very weak] Cylinder compression in a four stroke engine was several psi [very strong] The crankcase in a two stroke engine has to be very small so we can build some pressure when the piston is moving to BDC

12 11/ Crankcase Compression What is going to happen when the top of piston gets to here?

13 11/ A/F/O mixture squirts into cylinder because of crankcase compression

14 11/ Piston reaches BDC Cylinder fills with A/F/O mixture

15 11/ Intake/________ Stroke Another A/F/O mixture is sucked into crankcase while First one is compressed in cylinder Compression

16 11/ Down to bottom of page TDC BDC Piston gets to TDC Air/Fuel/Oil mixture is ignited in cylinder Piston is pounded Down the cylinder

17 11/ Blow-by adds to crankcase compression Crankcase Compression What is going to happen when the piston gets here?

18 11/ Power/Exhaust Stroke (TDC-BDC) TDC BDC Exhaust port is uncovered and exhaust starts leaving Still closed

19 11/ What’s going to happen when the piston gets back to TDC ANOTHER POWER STROKE OK, I get it !

20 11/ Every time the piston reaches TDC, there is another power stroke !

21 11/ Let’s make a chart

22 11/ Let’s make a chart

23 11/ Let’s make a chart

24 11/ Let’s make a chart

25 11/ Let’s make a chart

26 11/ Let’s make a chart

27 11/ Let’s make a chart

28 11/ Let’s make a chart

29 11/ Reed valve on the side of crankcase

30 11/200129

31 11/200130

32 11/200131

33 11/200132

34 11/ Tuned Exhaust

35 11/ Tuned Exhaust

36 11/ Tuned Exhaust

37 11/ Tuned Exhaust

38 11/ Power stroke every revolution

39 11/ Let’s watch CDX Disk 4-1 Look for two stroke with no reed valve

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41 11/ Oil mixing Pre-mix Have to mix before filling tank Oil injection Has separate fuel and oil tank and carburetor to mix proper amounts

42 11/ Advantages 2 Stroke Smaller/lighter Cheaper Less friction No oil to change Quicker acceleration Operate at different angles 4 Stroke More efficient No oil to mix Less emissions Less exhaust smoke More low RPM power

43 11/ Fuel to Oil mixtures 16 to 125 to 132 to 1 40 to 150 to 175 to to 1 Look in owners manual for exact ratio for your engine

44 11/ to 1 Mix 32 parts of gasoline to 1 part of oil 32 ounces of gas to 1 ounce of oil 32 pints of gas to 1 pint of oil 32 quarts of gas to 1 quart of oil 5 gallon gas can = How many ounces of oil 1 pint = 16 oz 2 pints = 1 qt 1 quart = 32 oz 4 quarts in a gal 32 X 4 = gal = 128 oz How am I going to figure this out? Think gals X 128 ozs would give me ozs of fuel 640 ozs of fuel divided by X oz of oil for 640 oz of fuel or 5 gallons

45 11/ Fuel to Oil mixtures 16 to 125 to 132 to 1 40 to 150 to 175 to to 1 Let’s say we are going snowmobiling for the Weekend and you have 1 quart of two stroke oil You figure it out

46 11/ How many gallons of fuel will be needed to mix with one quart of oil with a 50 to 1 ratio 1 pint = 16 oz 2 pints = 1 qt 1 quart = 32 oz 4 quarts in a gal 32 X 4 = gal = 128 oz

47 11/ There is always more than one way to figure something out

48 11/ Here is how I figured it out 32 oz times 50 = 1600 I will need 1600 oz of fuel for 32 oz of oil with a 50 to 1 ratio Since there are 128 oz in a gallon, divide 1600 by pint = 16 oz 2 pints = 1 qt 1 quart = 32 oz 4 quarts in a gal 32 X 4 = gal = 128 oz

49 11/ Mixing oil is critical If you forget to add oil for one tank of gas, you will destroy your engine If you mix too much oil with the gas Your engine will smoke a lot It will be hard to start It will have less power It might foul the spark plug (not start) If you don’t mix enough oil with the gas You will cause lots of engine wear Measure, don’t guess!

50 11/ Two stroke piston Notice the piston skirt scars (lack of oil) Notice the 2 ring lands (only have compression rings) Notice the ring pins (prevents rings from rotating And catching on cylinder ports)

51 11/ How to identify from outside Two stroke Exhaust port in center of cylinder Small crankcase Four stroke Exhaust port in end of cylinder Large crankcase

52 11/ Good uses of two stroke engines Because it is light, can be used at any angle, operates at high RPM Weed eaters Chain saws Boats Snowmobiles Dirt bikes

53 11/ Usually don’t see 2 strokes in Because of pollution, efficiency, lack of low RPM power, and convenience of not mixing oil Cars Trucks Road bikes Lawn mowers Generators

54 11/ Multiple cylinder two strokes The crankcase below each piston has to be sealed to create crankcase compression for that cylinder

55 11/ Two stroke engine questions?


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