The intake tube is held in place with a pair of 'O' rings at each end.<div>You need to remove the back plate/ carb body then pull with</div><div>a twisting motion on the intake tube straight out from the head.</div><div>Here is a exploded view of the 140-L engine.
When re assembling, I recommend using new 'O' rings as old ones
may leak.
Also be sure the valves are adjusted correctly. .002", two thousandths clearence.
YS engines are sensitive to leaks internally and externally.

Not trying to be condescending.</div><div></div><div>http://www.centralhobbies.com/Engine.../YSE140LEX.htm

If you are going to clean the valves and seats be EXTREMELY
careful not to damage the seats.
Be thorough in cleanliness when working on these engines as mistakes
can be costly.
If you are not familiar with YS engines I recommend sending them to
Richard at YS service in Minden, Nevada.</div><div></div><div>Happy flyin', Oscar</div>