Topic: did I make a big mess?

[mazingerzeca]

Hello all.
I think I did a big mess on my bike. Something really stupid. The bike is a cb750 F2 engine. I had an oil leak on the bottom of the engine, and I suspect that it came from the overflow tube which comes from the rocker arm cover. So I attached a zip bag to the tube and started the engine. After less than a mile a lot of oil came from the cylinder head area, lots and lots of oil. So maybe the bag was too tight to the overflow tube, and the pressure was so big that made the oil overflow, but where from? It was such a big amount of oil to be through the head gasket. Which was the way the oil followed?

[tlbranth]

I'm betting the bag didn't hurt anything. Enough pressure would've burst the bag before doing any real harm - I would think. It sounds like maybe you have a blowby problem. I'd do a compression test next and go from there.

[mazingerzeca]

That's what I thought. I can't think on any pressure able to blow a gasket and unable to blow a plastic zip bag. Besides, I had add oil in the tank, maybe too much? I feel like the biggest stupid on earth.

[Toxic]

There is no way your baggie did any damage.  But how much too much oil do you have in the bike?  If it's way too much that could explain your problem.

And before anyone else says it "Start using your dipstick Jimmie!!!"

[mazingerzeca]

After cleaning the engine, I rode a few miles, and it doesn' seem to leak anymore. Maybe the problem was too much oil in the tank, it was almost full. But, which way did the oil follow to go outside? It seemed to be between the cylinder head fins, but it was A LOT.

[MCRider]

After cleaning the engine, I rode a few miles, and it doesn' seem to leak anymore. Maybe the problem was too much oil in the tank, it was almost full. But, which way did the oil follow to go outside? It seemed to be between the cylinder head fins, but it was A LOT.

Identifying the source for sure is really the problem. That breather tube should not be blocked off with your bag. It sucks and blows as pistons go up and down. There is another breather that comes out of the base of the backside of the engine where the trans is, and enters the oil tank via a tube. But it isn't in the oil at that point, it actually travels via a tube in the tank up to the breather/condensor know at the top. So it sucks and blows as well.

That was all FYI. Unlikely the bag did any damage, but i can't think what it may have done to internal pressures.

Which brings us to the big leak. Was it really out of the head gasket? Not likely.

Or was it higher up between the middle fins on the head? If so, that's oil coming out from under the cam towers, which could be affected by pressure in the cam box. And yes it can really puke out of those areas, and no it won't fix itself.  

[Hush]

Which raises the subject of dip-sticks, I caught my partner checking her oil by removing the dip-stick then wiping it and not reinserting it all the way into the threads.
This would have given her the impression that she did not have enough oil and she would have added way too much.
Dip-stick etiquette: unscrew/wipe/screw all the way back in/remove again/read.

[750goes]

Hush,

that is wrong - it is called a DIP stick for obvious reasons, you dip it in and then read it for level, not SCREW it in..

[Toxic]

OH Cr@p now everyone is running to get their manuals out.

[Toxic]

Yup, sure enough no screwing allowed.

[MCRider]

Hush,

that is wrong - it is called a DIP stick for obvious reasons, you dip it in and then read it for level, not SCREW it in..

Agreed. All my bikes manuals say to uscrew, wipe off, then set it in place without screwing to get a reading.

The CB750 is a bit odd in that it simply sets into two opposing slots and turns very little. I've always compromised by setting it into the slots, but don't turn it. Being that its a tank, the engine doesn't know if its got a bit too much or too little.

[Don R]

My Honda mower has a little dip stick cartoon illustrating the dip.

[mazingerzeca]

The massive oil leak seemed to be between the fins, not through the head gasket, so I must understand that the big pressure moved the pucks under the camshaft towers, and irremediably I will have to change them 

[OldSchool_IsCool]

To screw or not to screw, that is the question!  I think it depends on the brand of oil you use.

*starts popping the popcorn*

[750goes]

OldSchool_isCool

it depends on how big of a dipstick is a dipstick 

[mystic_1]

The massive oil leak seemed to be between the fins, not through the head gasket, so I must understand that the big pressure moved the pucks under the camshaft towers, and irremediably I will have to change them 

That's possible I suppose, and I'm having a hard time thinking of where else the oil may have come from, but before you do that, clean the engine thoroughly and then ride it for a while to see if it leaks again.

mystic_1