Topic: High pressure air leak?

[greddm]

I started my bike yesterday and just before it started (turning over, but not running), I heard a weird sound like pressurized air escaping a small gap (cue fart jokes) - almost a whistle. Like when the cylinder is at the top of its stoke some air is leaking out. Could it be leaking out a valve or between the head?

Wasn't doing it a couple days ago.


1977 CB750

[dusterdude]

Or a loose spark plug

[eigenvector]

Can you reproduce it by turning the engine over by hand?

Maybe it is a head gasket issue.  I'd try to get it to do it manually before tearing anything apart.

edit:  Thinking about this for a second, manually turning over a sealed engine is pretty difficult.  What about operating the kickstarter pawl?

[Old Scrambler]

Could be an exhaust leak..........at the head. Look for exhaust stains around the header-joint.  Blown head gaskets will usually have a sucking sound when the piston is on intake.

[greddm]

Dusterdude gets the prize! It was a loose sparkplug! Never crossed my mind. Thanks everyone for the tips.


1977 CB750

[dusterdude]

Thank you,thank you very much.ill be here all week

[greddm]

Ok I lied, it was not a loose spark plug, after I pulled the engine for other issues, I found out it was leaking air between the head gasket.


1977 CB750

[LesterPiglet]

  Aww Duster. There's still the working mens clubs.
6 months? WTF?

[dusterdude]

Havent been to a mens club in a zillion years lol