Oil out the exhaust!!!

[loka]

In need of some help here.

Has anyone experienced oil coming out of the pipe? Not a little, a lot.

CB750, rebuilt bottom end, top was ok.
Oil level is where it should be

Help.

JJ

 

[hillsy]

.......CB750, rebuilt bottom end, top was ok......

Doesn't sound like your top was OK....sorry :-[

 

[loka]

just pulled the pipe off, number 2 was wet... could valve mis-adjustment have anything to do or am i looking at a top end job?

 

[Tim]

It could be simple as valve stem seals. Most likely IMHO.

If the exhaust valve stem seal is shot, oil from the head is going to go down the valve stem right into the exhuast, and not get burned up.

If it was coming up the cylinder past the rings, you'd be smoking a lot and it would probably not run well if there was actually liquid oil left in the pipe.

To diagnose you need a leak-down test. You pressurize the cylinder with air (through the plug hole) and measure the pressure it holds (compression test). If it leaks, you then see where it is leaking.

If out the carbs, it's intake valves. If out the exhaust, it's exhaust valves. If out the oil filler it's the rings.

 

[crazypj]

Re-set float levels in carbs.
most likely it's running too rich or flooding on one cylinder and the fuel/carbon mix looks like oil
Pull plugs and compare them, should all be same/similar colour
I think fuel line connects between 2&3 carbs, when you leave it on sidestand #2 gets any dirt and shut off sticks.

PJ

 

[loka]

Thanks for the tips. I will do some homework and report back.

JJ

 

[loka]

So,

After the compression test

4. 180 5 lb leak
3. 180 no leak
2. Off the deep end, fouled my gauge with oil.
1. Don't know, gauge screwed after 2. Assuming 180.

After float bowl measuring
4. 60 ml
3. 60 ml
2. 60 ml
1. 55 ml
Carbs are new out of the box, not a suspect.

Plugs all the same colour except 2 which was wet.

The biggest clue here is the raw oil spitting out of #2 exhaust port while doing the compression test..... Nuff said.

Should have done the top end...

Can anyone recommend a good cam for an 836 with 29mm CR's, Dyna EI, and a 4 into 1

thx, JJ

 

[crazypj]

So,

After the compression test

4. 180 5 lb leak
3. 180 no leak
2. Off the deep end, fouled my gauge with oil.
1. Don't know, gauge screwed after 2. Assuming 180.

After float bowl measuring
4. 60 ml
3. 60 ml
2. 60 ml
1. 55 ml
Carbs are new out of the box, not a suspect.

Plugs all the same colour except 2 which was wet.

The biggest clue here is the raw oil spitting out of #2 exhaust port while doing the compression test..... Nuff said.

Should have done the top end...

Can anyone recommend a good cam for an 836 with 29mm CR's, Dyna EI, and a 4 into 1

thx, JJ

You took them apart and checked?
It's quite probable the shut off valve is sticking?
It is 'clean' oil (still brown/gold?)
If it is passing oil into combustion chamber it will most likely be broken ring or damaged piston, (or both)
You do have a piston in #2?
Leaving seals off valve guides wont allow the quantities of oil you suggest, unless guides are totally trashed (I have seen top part snap at head surface and still barely smoke though)
Don't worry about a cam when it's not running right, (I know its a pain to get motor in and out, but, it's only 212 lbs )

PJ

 

[loka]

The motor is coming out today, all i know at this point is it is snafu. But, since it is coming out i thought i would swap cams and do the top end like i should have in the first place. If there is more wrong, which you suggest i will certainly find out.

JJ

 

[loka]

As it turns out the head was ok. We stripped it down and found the head gasket blown right at an oil galley. That would explain the copius amount of oil out the pipe.

Since we are in there, ordered up a mild cam from dynoman, new valve springs, seals, guides gaskets etc and we should be on our way.

JJ

 

[crazypj]

Usually if head gasket blows next to an oil gallery the sump gets pressurised (there's 175psi compression and only 45~70psi oil pump pressure)
Oil feeds up cylinder studs on CB750
If you have compression so low the oil can pump into combustion chamber and out exhaust there are probably other issues, it should have hydraulic locked with that much oil in there

PJ

 

[loka]

By 'other issues' you mean?

And could it be possible that it was just a faulty gasket? When i had my Sprite motor built 2 head gaskets failed before the third one stuck. That motor was built by a very competent mechanic.