BASCO 4-Stroke Horizontal 9hp OHV Engine Packet
EQ:
Names_____________________, ______________________ Date ________
Instructions:
Wear Safety Glasses at all times when working with the engine
Remove all fluids from your engine
Bring your engine and toolbox back to your table
Engine Identification:
For each item, indicate if you found the information in the booklet, on the tag of the
engine, or a combination of the two. And then write the specification below.
Page # or
Tag
Engine Make
What is the engine model?
What is the serial number?
Date of Manufacture
Why is the family # important
Displacement in CCs
.
in CCs
Specifications
Engine Disassembly:
Remember to wear your safety glasses at all times while working on the engines.
1. Check the external condition of the engine.
(Look for missing bolts or screws, cracks, leaks especially around gaskets, loose
parts, and deformed springs)
List any parts that are missing or damaged and alert your instructor. If none,
indicate so.
________________________________________________________________
________________________________________________________________
Instructor Signature ___________
Structural System
2. Remove the muffler guard and the muffler from the side of the engine.
3. Remove the cover between the gas tank and the shroud from the engine. Be
sure the fuel shut off is in the OFF position.
4. Remove the gas tank from the engine.
Note: Be sure you make a sketch of the kill switch linkage
Kill Switch Sketch
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3
Fuel / Air System
5. Remove the air filter cover and the filter, and check the air filter.
Is your air filter clean and how do you know?
______________________________________________________________________
______________________________________________________________________
Under normal engine operation how often should an air filter be changed?
______________________________________________________________________
6. Remove the air filter mount, attached to the carburetor.
7. Remove the engine shroud and rewind starter.
Electrical System
8. Make a sketch of your magneto and its linkages.
Ignition Coil Sketch
9. Remove the magneto and spark plug.
10. Remove, dismantle, and inspect the carburetor.
Instructor Signature ___________
(Note: You may move on to the questions while waiting for the instructor)
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CRITICAL THINKING
Define the Electrical Terms in your words and explain why each is important:
Do you see any differences between this carburetor and the one from the previous
engine? (Specify)
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______________________________________________________________________
The carburetor linkage is composed of wires and springs. What does it control?
______________________________________________________________________
______________________________________________________________________
Why is it important that the linkage is replaced just as it came from the engine? Be as
specific as possible.
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
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What is the purpose of a carburetor?
______________________________________________________________________
______________________________________________________________________
11. Make a sketch of the throttle linkage. Be Specific.
NOTE: (This will be your only means of properly reattaching the linkages)
Throttle Linkage Sketch
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12. Remove the governor/ throttle linkage from the engine entirely.
Be sure you keep track all of the pieces.
13. Remove the gas tank mount from the top of the engine.
14. Remove the overhead valve cover
15. Make a sketch of valve layout in the OHV setup.
Note the differences between the OHV and the L-Head valves.
OHV Sketch
16. Completely disassemble the valve assembly.
17. Remove the cylinder head.
Note: The valve pushrods will fall out when you remove the cylinder head or the
valves.
Instructor Signature ___________
(Note: You may move on to the questions while waiting for the instructor)
What differences do you see between the OHV setup and the L-Head? Why are these
significant?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
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What is the purpose of the valves?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
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Crankcase
18. Remove the flywheel assembly.
Be sure to keep track of all pieces.
19. Remove the crankcase side cover.
Be sure to loosen all of the bolts before removing any of them.
20. Rotate the crank shaft until both valves are closed. The cam gear will now slide
out. Remove the governor gear, cam gear, and tappets.
21. Rotate the piston to Bottom Dead Center and remove the piston and crankshaft.
What is the purpose of the governor on your engine?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
What is the second gear attached to the governor gear for?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
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What is the purpose of the timing marks on the cam and crank gear and why are they
important?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
22. Inspect all parts of your engine for wear or damage and provide measurements
for the specific parts below.
Instructor Signature ___________
(Note: You may move on to the questions while waiting for the instructor)
ENGINE SPECIFICATIONS
ENGINE MODEL_____________
Man. Specs.
Your
Measurement
Stroke
Bore
X
XXXXXXXX
Crank Inside Diameter
(PTO Side)
Y
X
XXXXXXXX
Y
Spark Plug Gap
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Engine Assembly:
Reassemble the engine using the following steps. Remember to replace all gaskets and
to use PROPER TORQUE VALUES on all fasteners using the star pattern when
necessary.
1.
2.
3.
4.
Piston and crankshaft (Use the ring compressor)
Cam gear, tappets, and governor gear
Crank case side cover (Use star pattern when replacing bolts)
Cylinder Head (Valves must be gapped to .004” to .006”)
Instructor Signature ___________
5. Fly Wheel Assembly
6. OHV Cover
7. Gas Tank Mount
8. Throttle Assembly
9. Carburetor
10. Ignition Coil (Coil must be gaped .003” from flywheel)
Instructor Signature ___________
11. Shroud
12. Gas Tank and Rewind starter cover
13. Air Filter Mount and Air Filter
14. Gas Tank/ Shroud Cover
15. Muffler
16. Muffler guard
Instructor Signature ___________
*** Gaskets should be in place anywhere metal will touch metal.
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Once the engine is assembled, check for spark and compression
17. Check for spark
18. Compression Test Readings:
Dry __________PSI.
Instructor Signature ___________
19. Fill your engine with oil and gas
20. Compression Test Readings:
Wet _________PSI.
Instructor Signature ___________
Run your engine (with the instructor’s permission)
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