Topic: Crankcase pressure

[Ravie]

The pressure in the oil side of my crankcase is rather high. When I ride the bike it builds up quite a bit of pressure in the oiling system - so much so that it will push a bit of oil past the cap. If I open it directly after I've ridden it sounds like I'm opening a fresh pop bottle!

Keep in mind, if this makes any difference, that I now have 38 actual road miles on the bike, so it's certainly not fully broken in yet. Is this an issue of the rings are just not seated and the firing pressure is building up on the oil side of the pistons?

[CB650CPastor]

How is the crankcase vented? There should never be that kind of pressure.

[mystic_1]

Since you have a 750 I'm assuming that you mean your oil tank is becoming pressurized - this wouldn't be a problem with crankcase pressure since the oil tank is vented seperately.

Make sure the vent line on the back of the oil tank is not plugged (the larger, upper spigot).  The smaller, lower spigot should be connected to the return nipple at the rear of the motor.

mystic_1

[Ravie]

Since you have a 750 I'm assuming that you mean your oil tank is becoming pressurized - this wouldn't be a problem with crankcase pressure since the oil tank is vented seperately.

Make sure the vent line on the back of the oil tank is not plugged (the larger, upper spigot).  The smaller, lower spigot should be connected to the return nipple at the rear of the motor.

mystic_1

I have to actually confirm but...I think I may have this connected backwards. That would explain some #$%*!  lol!

[Ravie]

Oh man, Mystic. You're the fecking king. I had the upper breather connected to the damn valve cover spigot. Thanks a bunch!

[mystic_1]

Oh yeah, that would do it

Both of those lines should just be vented to atmo, down in front of the swingarm pivot.

mystic_1

[Ravie]

Yep. I don't blame the PO for pushing me in that direction...because it's their fault I connected it wrong...they had it that way to begin with!  I simply disconnected the valve cover hose and stuck it down next the the oil lines and made a new vent hose for the top oil tank vent. No problemo.