Deck 11: Two-Stroke Engine Lower-End Inspection

Question 1

Describe the procedure for inspecting the engine crankcases and why it is important to be thorough.

Answer 1

Begin by checking for loose fitting bearings and worn out fasteners. Check the engine seals, especially those that are inside the engine cases. Then check all of the ball bearings. You should inspect all engine components carefully because a tear down of the lower end is not done frequently and it's important to make sure that the job is done right and there are no existing problems or soon-to-be problems.

Question 2

Explain the procedure for inspecting a crankshaft and the three measurements a technician should make.

Answer 2

A technician should first check the side clearance of the connecting rod with a feeler gauge between the big end of the rod and the flywheel. They will then measure the radial clearance by putting the crankshaft on a pair of V-blocks and then use a dial indicator to check for any up and down movement of the rod. Finally, the technician will check run out while the crankshaft is slowly rotated on the V-blocks as the dial indicator touches the flywheel.

Question 3

The _____ is usually damaged also when a problem with the transmission occurs.

A)shift fork
B)shift pawl
C)shift drum
D)clutch basket

Answer 3

A

Question 4

The ______is the most critical component of the transmission that should be inspected but is often overlooked.

A)shift fork
B)shift pawl
C)shift drum
D)clutch basket

Question 5

The most common bearing you will find in a two-stroke engine is the ball bearing.

Question 6

What are the six clutch components that should be inspected and measured?

Question 7

Describe the procedure for checking a two stroke engine for bad main bearings and what tool is useful in pin pointing the bad bearing.

Question 8

An engine seal can be reused after removal if it is "live".

Question 9

Most two-stroke engines require you to remove the top end to split the engine cases.

Question 10

Modern two-stroke motorcycles do not use constant mesh transmissions.

Question 11

You may need a ________ to remove the crankshaft from the crankcases.

A)dead blow hammer
B)ball peen hammer
C)sledge hammer
D)hydraulic press

Question 12

Put a ball bearing in the freezer before installation.

Question 13

Use a _______ to measure the shift forks.

A)vernier caliper
B)dial gauge
C)feeler gauge
D)snap gauge

Question 14

Describe the procedure for doing a thorough bench check on freshly reassembled two-stroke engine and why this is important.

Question 15

The ____is the most commonly replaced part of a two-stroke crankshaft.

A)flywheel
B)wrist pin
C)connecting rod
D)big end pin