Model and Serial Numbers

1. Model and Serial Numbers

2. 1 P 6 1 M U A MTD Vertical Engine Model Designators Major Revision Change Compliance U United States (50 State) H Europe C California 0 (Zero) 49 State G U.S.(49) and Europe W U.S.(50) and Europe P= Vertical (1 cyl.) Q= Vertical (2 cyl.) Starter/Alternators 1=Recoil start 2=Electric start (12V) 3=E. start/alt. 18W 4=E. start/alt. 3A/5A 5= AutoChoke/ Recoil 6= AutoChoke/Electric Start Bore Dia. (mm) End Product B Mower (long shaft M0) C Chipper/Shredder M Mower (long shaft/no shroud) D Mower (long shaft M1) N Mower (short shaft M0) E Mower (short shaft M1) P Mower (long shaft M0) F Mower (short shaft/no shroud) Q Mower (short shaft M0) I Mower (long shaft/M0) T Tiller L Log splitter W World Tiller

3. 1 6 1 - S H A MTD Horizontal Engine Model Designators Starter/Alternators 1=Recoil start 2=Electric start 3=E. start/alt. 20W/20W 4=E. start/alt. 3A DC/5A Major Revision Change Compliance U United States (50 State) H Europe C California 0 (Zero) 49 State G U.S.(49) and Europe W U.S.(50) and Europe Bore Dia. (mm) End Product C Chipper/Shredder J Snow/No tank L Log splitter R Tiller (slow reverse) S Snow T Tiller V Verticutter

4. 1P65FH/0510271A0023 MTD Engine Serial Numbers Year Month Date Producing Line# and Shift#: 1A=Line 1, 1st Shift 1B=Line 1, 2nd Shift 2A=Line 2, 1st Shift 2B=Line 2, 2nd Shift 3A=Line 3, 1st Shift 3B=Line 3, 2nd Shift Engine number Model number

5. Vertical Shaft • Three basic series • Same basic design • The main difference between engines in the same series is the flywheel and module

6. Engine Features - Benefits Electronic Ignition Capacitor Discharge Ignition provides higher ignition voltage required for easy, dependable starting with no maintenance. Forged Steel Crankshaft Better strength/weight ratio than cast iron which means stronger and more durable. Heavy Duty Crankshaft Ball Bearing Can withstand higher loads and reduces wear caused by oil contamination or low oil conditions. RFI/EMI Shielded Plug Boot Shielded plug boot with the resistor spark plug will dramatically reduce the amount of unwanted electrical noise. Mechanical Governor Provides precise control of engine speed and responds 30% faster to sudden load increases than traditional air vane designs. Results in smoother, consistent, and trouble-free cutting power. Overhead Valve Design with Cross-flow Cylinder Head More efficient, cleaner burning engine. Results in more power and reduces fuel consumption when compared to conventional side-valve engines. Dual Element Air Filter Foam pre-cleaner, pleated paper filter with debris ejection slots provide superior protection. Cast Iron Cylinder Sleeve Automotive style piston and rings riding in a cast iron sleeve cylinder provides longer life while reducing bore wear and oil consumption.

7. Horizontal engines The differences between the snow and tillers engines are: • Different mufflers • Different air intake

8. MTD® Snow Engine • OHV with Cross-Flow Cylinder Head Design • 208cc Engine Displacement • Cast Iron Cylinder Sleeve • Forged Steel Crankshaft • Cast Iron Camshaft • Heavy Duty Crankshaft Ball Bearings • Mechanical Governor • Mechanical Compression Release • Extended Oil Fill & Dipstick • Extended Oil Drain • 2 Quart Industrial Steel Fuel Tank • Large Automotive Style Ratcheting Fuel Cap • Ergonomic Oversize Mitten Grip Handle • Push/Pull Safety Key Switch • Low Tone Muffler with Heat Shield • Push Button 110V Electric Starter UL/CSA Approved • Alternator for Lights & Optional Heated Hand Grips • IDI Ignition • Resistor Spark Plug with RFI/EMI Shielded Boot • 3-Year Residential / 1-Year Commercial Warranty

9. OHV with Cross-Flow Cylinder Head Design • 208 cc Engine Displacement • Cast Iron Cylinder Sleeve • Forged Steel Crankshaft • Cast Iron Camshaft • Heavy Duty Crankshaft Ball Bearings • Mechanical Governor • Mechanical Compression Release • Extended Oil Fill & Dipstick • 2 Quart Industrial Steel Fuel Tank • Large Automotive Style Ratcheting Fuel Cap • Variable Speed Control • Low Tone Muffler with Heat Shield • Induction Discharge Ignition • Resistor Spark Plug with RFI/EMI Shielded Boot • 2-Year Residential / 1-Year Commercial Warranty New Tiller Engine for 08 Featured on Troy-Bilt Bronco & Super Bronco Models

10. A review of basic carburetor theory

11. Throttle body Ventri Fuel chamber (Float bowl) Fuel pick up tube Carburetors AIR

12. Throttle plate Air bleed Bowl vent Emulsion tube Metering jet Carburetors

13. Idle jet Idle air bleed Choke Idle port Low pressure Transition ports Idle circuit Carburetors Fuel and air mix Increased Vacuum

14. Carburetors

15. Carburetors

16. Carburetors

17. Same opening area as the needle screw Jets vs. Needle screws Why are jets better than needle screws? Needle screw VAPOR LOCK Jet Vapor Lock What is Vapor lock?

18. Troubleshooting and Failure Analysis

19. When troubleshooting an engine, Diagnose with Eyes Open! • First, check the oil: • What does this tell you? • Take a look at the air filter: • What condition is it in? • Fuel: • A big problem area.

20. Cleanliness: • Good indicator of the level of care and type of use. • Signs of mouse nest? • Mud-packed / covered with wet grass? • Safety: • Guards in place? Safety bail disabled? • Pull the rope • Pull too easily?……Got compression? • Pull too hard?……Crankshaft straight?……Hydro-lock? • Jerks back?……Flywheel key?……Blade on tight? • Starter rope broken?…Probably a reason.

21. Troubleshooting • Periodic maintenance will solve a lot of performance issues. • Check valve lash, oil, fuel, and all filters before troubleshooting. NOTE: Most jerky starts on the MTD engine are due to loose valve lash. • Inspect/replace the spark plug.

22. Troubleshooting • Ignition- sufficient spark to start combustion in the cylinder, occurring at the right time. • Compression- enough pressure in the cylinder to convert combustion into kinetic motion. It also needs sufficient sealing to generate the vacuum needed to draw in and atomize the next intake charge. • Fuel- correct type and grade of fresh gasoline; in sufficient quantity, atomized (tiny droplets) and in correct fuel/air proportions. • Flow- if all of the above conditions are met, but the flow of air is constricted on the inlet or exhaust side it will cause the engine to run poorly or not at all. This also includes the ensuring the valves are timed to open at the proper time.

23. Troubleshooting • Isolate the fuel system first by performing a prime test. • Squirt clean, fresh fuel into the throat of the carburetor. • If the engine starts and burns the prime, the problem is in the fuel system.

24. Troubleshooting the fuel system • Drain and replace the fuel. • Check the drained fuel for: • Dirt • Water • Is it stale? • Alcohol • Check fuel tank, lines and vents • Check the carburetor

25. Troubleshooting the Ignition System • Check for spark using a spark tester. • Never ground a sparkplug against the head! The fuel/air mix coming out of the spark plug hole can ignite.

26. If there is no spark: • Check the blade brake switch. • Check the air gap of the module. • Check the ground on the module. • Check the flywheel key. • If every thing checks out OK, replace the module.

27. Troubleshooting Compression • If there is spark, check the spark plug again. If it is wet, the plug is bad. If it is dry, do a compression test. • Near zero compression is most likely a stuck valve or valve lash is to tight. • Low compression, look at the valve seats and piston rings. • High compression is most likely excessive valve lash, a block muffler or a partial hydro-lock.

28. Troubleshooting an Engine That is Hard to Pull If the rope pulls out some then stops: • Check for hydro-lock. • Make sure the blade is not binding. • With the plug removed turn the blade, If the blade turns look at the starter. • Check for debris trapped in the blade brake. • Open the engine.

29. Troubleshooting an Engine That is Hard to Pull A jerky starter rope: • Check the valve lash!!! • Check the flywheel for a sheared or missing key. • Check the ACR on the cam. • Check the cam timing.