Choke bore cylinders compress the rings at the bottom of the stroke.

• A. True
• B. Not stated
• C. Depends
• D. False

Answer: (D)

The important idea is how piston rings seal and how bore geometry affects that sealing. Piston rings are kept against the cylinder wall by their own spring tension and by the gas pressure in the combustion chamber as the piston moves. A choke bore cylinder means the bore is slightly tapered, which can help the rings seat and seal more effectively, but it does not cause the rings to be compressed specifically at the bottom of the stroke. The rings aren’t “crushed” or uniquely compressed there; their pressure against the bore varies with piston position due to gas pressure and ring tension, not because of bottom-stroke compression from the bore shape. Therefore the statement is not correct.