Topic: cb750K1 - foaming oil + dripping out the tank breather

[Salman_z8]

A little under the weather, i will post some pics tomorrow.

I am strongly thinking, that i should have tried retorquing the head prior to diassembling, but that ship has sailed lol

I checked the exhaust valves in the guides, and they dont feel sloppy, at all.

The intake ports are clean, but i will check those as well tomorrow, but i have to remove seals to check.

I havnt made it to the machine shop yet.

[PeWe]

The modern too thick head gaskets will reduce compression and fun power too.
If restoring cylinder with new pistons, later 392 pistons in K0-K6 will add a little compression as compensation for the thick gasket.

[Don R]

 It reminds me of a car that has a blown head gasket and is blowing compression into the cooling system.

[Salman_z8]

The modern too thick head gaskets will reduce compression and fun power too.
If restoring cylinder with new pistons, later 392 pistons in K0-K6 will add a little compression as compensation for the thick gasket.

Thats is a good idea.
I will try that with my next one.
It has an andrews D cam, and dont know what pistons it has, havnt taken it apart.

[PeWe]

My KHD cam did not match stock pistons, valve contact.

Think it was the 392 pistons. But they were not higher than stock where valves hit.

[Salman_z8]

Someone smack me across the face.
I will give you guys something to laugh at.

So i started my k0, that i had built 4 years ago, and never rode it.
Ran great, lots of low mid power, ran very good.
Broke it in, 150 miles.
Going good.

I was missing a couple vent hoses, and i had a couple laying around on the table, so i put em on.

Went for a ride, all great, stop to take a break, and oil dripping out the tank vent hose. Huh

Needless to say, that hose came from from the same bike that was blowing oil.

Of course, i disregard that AGAIN.

Started checking stuff. Etc etc

Without taking the rocker hose off, i pulled the end out to see if there was any oil in that as well. None, bone dry.
Blew into it and was clear, wtf

Anyways 5 mins later i take the hose off, because due to some miracle, when i blew into it it wasnt clear. So i took it off, not to check the hose but the rocker vent itself .. dumb moment again

And it was clear, started the engine and just felt what was coming out the top, and it was breathing quite a bit of pressure, which it wasnt with the hose on.

Checked the hose again, blew from the bottom, and clear.
Blew from the other end, and blocked shut.

Ran a wire through the hose and leaves and crap fell out.
It was magically plugged like a reed valve, but the wrong direction.

Boy i sat there and laughed at my own stupidity for a bit
 
Hahaha

Having been wrenching on old bikes for 20 years, with dozens of engine builds, and i missed that darn hose.

However, it was blessing for the original bike in this thread, because in its case, i am 100% sure that the head gasket wasnt sealing fully, and thats where the oil was making its was into the bores.

But the big problem, was that HOSE

[Salman_z8]

My KHD cam did not match stock pistons, valve contact.

Think it was the 392 pistons. But they were not higher than stock where valves hit.

I got a couple motors open on the table, once they are buttoned up, i will find out whats in that motor.
May be it has a 836 kit, who knows, its dealer stamped #767 .. probably a warranty set of cases with later head, and 10 hole clutch cover. However the case bolts are not flanged, and early bolt and washer style.

Looking forward to that

[HondaMan]

Someone smack me across the face.
I will give you guys something to laugh at.

So i started my k0, that i had built 4 years ago, and never rode it.
Ran great, lots of low mid power, ran very good.
Broke it in, 150 miles.
Going good.

I was missing a couple vent hoses, and i had a couple laying around on the table, so i put em on.

Went for a ride, all great, stop to take a break, and oil dripping out the tank vent hose. Huh

Needless to say, that hose came from from the same bike that was blowing oil.

Of course, i disregard that AGAIN.

Started checking stuff. Etc etc

Without taking the rocker hose off, i pulled the end out to see if there was any oil in that as well. None, bone dry.
Blew into it and was clear, wtf

Anyways 5 mins later i take the hose off, because due to some miracle, when i blew into it it wasnt clear. So i took it off, not to check the hose but the rocker vent itself .. dumb moment again

And it was clear, started the engine and just felt what was coming out the top, and it was breathing quite a bit of pressure, which it wasnt with the hose on.

Checked the hose again, blew from the bottom, and clear.
Blew from the other end, and blocked shut.

Ran a wire through the hose and leaves and crap fell out.
It was magically plugged like a reed valve, but the wrong direction.

Boy i sat there and laughed at my own stupidity for a bit
 
Hahaha

Having been wrenching on old bikes for 20 years, with dozens of engine builds, and i missed that darn hose.

However, it was blessing for the original bike in this thread, because in its case, i am 100% sure that the head gasket wasnt sealing fully, and thats where the oil was making its was into the bores.

But the big problem, was that HOSE

Man, that's one for the books!

[BenelliSEI]

Amazing what be found in even the smallest hoses!

[willbird]

Amazing what be found in even the smallest hoses!

I was over to visit a friend once, we were decimating vermin with a single shot break open 223 rifle, firing out an upstairs window down into his garden. His will yelled that lunch was ready so we left the rifle there. We ate lunch then went back upstairs. Just out of habit he glanced through the rifle bore before loading it. Hmm the bore was blocked. grabbed a cleaning rod and pushed a patch through it. Some little wasp had started to make a paper nest in the .224" dia rifle bore. Good thing he looked ;-).

[newday777]

Well whatdahyaknow! Ya found it!
Some critters sure did give you the runaround.
Glad you found it and could laugh about it.

[scottly]

I tried to tell you it was a problem with the breather plumbing.
 

Thank you for the detailed replies.
I will be looking into it more, and more than likely will pull the topend off.

WTF!!?? NONE of your symptoms have anything to do with the top end of the motor!! What is the level of the oil in the tank on the dipstick?

[Salman_z8]

I tried to tell you it was a problem with the breather plumbing.
 

Thank you for the detailed replies.
I will be looking into it more, and more than likely will pull the topend off.

WTF!!?? NONE of your symptoms have anything to do with the top end of the motor!! What is the level of the oil in the tank on the dipstick?

I know, and i swear i checked the breather many times.
The breather hose was just invisible to my cognition

[Salman_z8]

Someone smack me across the face.
I will give you guys something to laugh at.

So i started my k0, that i had built 4 years ago, and never rode it.
Ran great, lots of low mid power, ran very good.
Broke it in, 150 miles.
Going good.

I was missing a couple vent hoses, and i had a couple laying around on the table, so i put em on.

Went for a ride, all great, stop to take a break, and oil dripping out the tank vent hose. Huh

Needless to say, that hose came from from the same bike that was blowing oil.

Of course, i disregard that AGAIN.

Started checking stuff. Etc etc

Without taking the rocker hose off, i pulled the end out to see if there was any oil in that as well. None, bone dry.
Blew into it and was clear, wtf

Anyways 5 mins later i take the hose off, because due to some miracle, when i blew into it it wasnt clear. So i took it off, not to check the hose but the rocker vent itself .. dumb moment again

And it was clear, started the engine and just felt what was coming out the top, and it was breathing quite a bit of pressure, which it wasnt with the hose on.

Checked the hose again, blew from the bottom, and clear.
Blew from the other end, and blocked shut.

Ran a wire through the hose and leaves and crap fell out.
It was magically plugged like a reed valve, but the wrong direction.

Boy i sat there and laughed at my own stupidity for a bit
 
Hahaha

Having been wrenching on old bikes for 20 years, with dozens of engine builds, and i missed that darn hose.

However, it was blessing for the original bike in this thread, because in its case, i am 100% sure that the head gasket wasnt sealing fully, and thats where the oil was making its was into the bores.

But the big problem, was that HOSE

Man, that's one for the books!

It sure is. 

[Salman_z8]

Amazing what be found in even the smallest hoses!

I was over to visit a friend once, we were decimating vermin with a single shot break open 223 rifle, firing out an upstairs window down into his garden. His will yelled that lunch was ready so we left the rifle there. We ate lunch then went back upstairs. Just out of habit he glanced through the rifle bore before loading it. Hmm the bore was blocked. grabbed a cleaning rod and pushed a patch through it. Some little wasp had started to make a paper nest in the .224" dia rifle bore. Good thing he looked ;-).

Its crazy eh what those critters can do

[Salman_z8]

Well whatdahyaknow! Ya found it!
Some critters sure did give you the runaround.
Glad you found it and could laugh about it.

Yes sir