Topic: Compression coming out the side of the head/jugs at the headgasket 76 cb 550

[Way Way norcal]

Kind of strange to me.
Started the bike up in the morning cold and as the bike warmed up and I reved it I could see white condensation coming out at the number one cylinder on the side of the head.  I am curious why no oil is leaking out and only air.    I am reasonably certain it is not an exhaust leak. 
Has any had any experience with this?

[Way Way norcal]

did that a number of times and it really appears it is leaking from the head gasket. 
I agree.  I looked and looked for oil and nothing.  Can't quite figure it out

[scottly]

Sounds like a case of a "blown" head gasket not sealing the combustion gasses in the cylinder. There is no oil because the oil passages are not in the area of the blowout. Can you see any fire spitting out if you run the motor in the dark, or hear a "tick"? Don't run it too long, or the hots gasses can cut into the head and/or cylinder block. 

[alacrity]

What is coming out of your breather/breather tube at the top of the engine? if you stick your finger in the end of the tube, do you feel pulses? Is there smoke?  Remove it from the cover, run the engine. Stick your finger over the pipe fitting at the breather cover. Same pressure as at the end of the tube or more?  let it run like that and now see if you are still getting that wispy crap leaking out.  It may be a pointless exercise... but... go with me here for a sec.

[Way Way norcal]

well, I pulled the head and I am putting on a new gasket.  I work on cars and trucks and do headgaskets weekly.  So this little bike is actually a pleasure to work on.  I am still familiarizing myself with the motor so it is not a huge deal to tear it apart and learn.

One thing is TDC.  On most of the rigs I work on TDC is has to be on the compression stroke when lining up the cam pin or marks. 
On this 550 motor TDC can be on the compression OR exhaust stroke as long as the center of the notch  on the right side of the cam is lined up with the surface of the cylinder head...
I certainly hope that is correct.
The manual I have does not say set the timing mark to TDC compression stroke then install the cam.

[OldSchool_IsCool]

When you put the head cover back on, be sure to back out the tappet adjusters all the way AND tie back the tappets.  Typically you can loop a rubber band over the intake tappet, out the inspection hole, thru the exhaust inspection hole and over the exhaust tappet.  Affixing a head cover on a 500/550 with the tappets flopping around is just begging to bend something. 

As for cam timing, cyl #1&4 at TDC, notch in cam shaft at 3 o'clock, (or 9 o'clock). These engines use a wasted spark ignition, so you it doesn't much matter.

[scottly]

Was there an obvious blown-out area in the gasket?

[Way Way norcal]

on the side where the leak appeared to be there were small valleys or creases in the gasket. It looked normal to me and didn't look like it should have been leaking.  Still not sure.
I ran the bike for a good long while checking the area where it was leaking.  I am pretty certain that head gasket was blown.