Blown head gasket at idle…

Peter1127

Peter1127

Donating Member
Hi guys, new Hayabusa owner here. Bought a dismantled K2 with a failed rod bearing. It was a rolling chassis and 20boxes of parts. Good way to learn about your new bike:-) Got the manual and exploded views so not too bad. Needed to take some snapped off header bolts and pair studs out: fortunately the old “welding a nut on it” trick sorted that. Got a fresh crank&rods and put it all together. Bike started immediately, idled ok but after 5min of idling and blipping the throttle it started to smoke horrendously. Took the plugs out and cyl3 spits quite a bit of cooling fluid. Didnt know you could blow a head gasket at idle… Was a new gasket, torqued to spec. Cooling system was filled and vented and it didn’t overheat.

Gonna take the head off and have a look, curious about your thoughts.
 
@Peter1127 First of all......welcome.....

Secondly, that sucks to hear.......you are in good hands as lots of good, sound advice is to be found around here...

I echo a warped or out of true head....
--------------------------------------------------------------------------------------------------------------------------------------------------------------

A kind of/sort of related story.......my brother has (amongst many bikes) a 1969 BSA 500 Gold Star.....when he was restoring it, it was smoking while running so he took the head off, put on a new gasket, valve seals, new valve seats, checked the rings and bore.....

Put it all back together and it still smoked......he thought maybe he got a bad valve seal or head gasket so he did a compression leak down and it was good.....but still smoked....

He finally got frustrated so took the head off to a machine shop and they checked it's trueness.....and it was good.....they got interested so did some sort of micro test and found a crack in the head no visible to the naked eye and they figure the heat made it open up......

He got another head, put it all back together and it smoked...he was ready to set fire to the whole thing but took the head off, took it to the same machine shop, they did the micro test and found a crack in the head in a different spot.....but found somewhere in the US that would weld the head.....it wasn't real inexpensive but that fixed it....
---------------------------------------------------------------------------------------------------------------------------------------------------------------

I know this has nothing to do with your problem but just a quick story to point out that you aren't alone........
 
Peter1127 said:
Hi guys, new Hayabusa owner here. Bought a dismantled K2 with a failed rod bearing. It was a rolling chassis and 20boxes of parts. Good way to learn about your new bike:-) Got the manual and exploded views so not too bad. Needed to take some snapped off header bolts and pair studs out: fortunately the old “welding a nut on it” trick sorted that. Got a fresh crank&rods and put it all together. Bike started immediately, idled ok but after 5min of idling and blipping the throttle it started to smoke horrendously. Took the plugs out and cyl3 spits quite a bit of cooling fluid. Didnt know you could blow a head gasket at idle… Was a new gasket, torqued to spec. Cooling system was filled and vented and it didn’t overheat.

Gonna take the head off and have a look, curious about your thoughts.
Click to expand...
on a positive note, you’ll literally know your busa inside out by the time she hits the road.
 
Bumblebee said:
@Peter1127 First of all......welcome.....

Secondly, that sucks to hear.......you are in good hands as lots of good, sound advice is to be found around here...

I echo a warped or out of true head....
--------------------------------------------------------------------------------------------------------------------------------------------------------------

A kind of/sort of related story.......my brother has (amongst many bikes) a 1969 BSA 500 Gold Star.....when he was restoring it, it was smoking while running so he took the head off, put on a new gasket, valve seals, new valve seats, checked the rings and bore.....

Put it all back together and it still smoked......he thought maybe he got a bad valve seal or head gasket so he did a compression leak down and it was good.....but still smoked....

He finally got frustrated so took the head off to a machine shop and they checked it's trueness.....and it was good.....they got interested so did some sort of micro test and found a crack in the head no visible to the naked eye and they figure the heat made it open up......

He got another head, put it all back together and it smoked...he was ready to set fire to the whole thing but took the head off, took it to the same machine shop, they did the micro test and found a crack in the head in a different spot.....but found somewhere in the US that would weld the head.....it wasn't real inexpensive but that fixed it....
---------------------------------------------------------------------------------------------------------------------------------------------------------------

I know this has nothing to do with your problem but just a quick story to point out that you aren't alone........
Click to expand...
I would hang the bad heads on my garage wall as a reminder. lol!
 
202mphbusa said:
maybe head gasket blew
causing coolant in the oil,,,which THEN cost the rod bearing
Click to expand...
THAT is very plausible: water leak caused a lubrication issue. All other rod bearing also didnt look fresh, neither were the main bearings. Fortunately cam journals are fine and so are cams, those are also seriously oil dependent.

In one of the 20 boxes was the old head gasket and that looked fine. So cracked head/barrel sounds like a real possibility. Tearing it down this weekend, will keep you updated.
 
Bumblebee said:
@Peter1127 First of all......welcome.....

Secondly, that sucks to hear.......you are in good hands as lots of good, sound advice is to be found around here...

I echo a warped or out of true head....
--------------------------------------------------------------------------------------------------------------------------------------------------------------

A kind of/sort of related story.......my brother has (amongst many bikes) a 1969 BSA 500 Gold Star.....when he was restoring it, it was smoking while running so he took the head off, put on a new gasket, valve seals, new valve seats, checked the rings and bore.....

Put it all back together and it still smoked......he thought maybe he got a bad valve seal or head gasket so he did a compression leak down and it was good.....but still smoked....

He finally got frustrated so took the head off to a machine shop and they checked it's trueness.....and it was good.....they got interested so did some sort of micro test and found a crack in the head no visible to the naked eye and they figure the heat made it open up......

He got another head, put it all back together and it smoked...he was ready to set fire to the whole thing but took the head off, took it to the same machine shop, they did the micro test and found a crack in the head in a different spot.....but found somewhere in the US that would weld the head.....it wasn't real inexpensive but that fixed it....
---------------------------------------------------------------------------------------------------------------------------------------------------------------

I know this has nothing to do with your problem but just a quick story to point out that you aren't alone........
Click to expand...

Thanks for the welcome! Hope my repair goes more smooth :-) Already checked for used heads but they seem scarce. Welding seems like a last resort with the purpose of selling the bike quickly before it lets go again.
 
Bumblebee said:
It was a real head scratcher.....my brother is a serious wrench.......I've seen him fix things for people that mechanics turned away because it was too complex....

He certainly didn't think 2 different heads could be bad.....
Click to expand...
Sometimes you run into those random issues that leave you scratching your head and knockdown your confidence making you second guess yourself. Reminds me of the hours and hours I spent that one time trying to figure out what was going to my gen2 just to find that the fuel pump relay was testing good on the bench test but, failing open when the fuel pump current draw tried going across it. I’ll never forget that issue and even ordered a spare fuel pump relay for the gen3 to carry with me since it’s different from the gen2.
 
mabupa said:
Sometimes you run into those random issues that leave you scratching your head and knockdown your confidence making you second guess yourself. Reminds me of the hours and hours I spent that one time trying to figure out what was going to my gen2 just to find that the fuel pump relay was testing good on the bench test but, failing open when the fuel pump current draw tried going across it. I’ll never forget that issue and even ordered a spare fuel pump relay for the gen3 to carry with me since it’s different from the gen2.
Click to expand...
From your advice, I have a new fuel pump relay sitting on my work bench just in case....
 
Bumblebee said:
From your advice, I have a new fuel pump relay sitting on my work bench just in case....
Click to expand...
I need to dig my gen2 spare out of the busa’s toolkit so I can find it a new home with a forum member.
The gen3 one is about half the size of the gen2’s.

IMG_9986.webp
 
Took the head off and there you have it. If you look carefully you can see it goes all the way to the valve guide. . Did take quite some amount of engines apart but this is my first encounter with a cracked head. Didnt see that before because I couldnt be bothered to clean the combustion chambers. Wont make that mistake again. Mistery solved and thanks for your help!


head.webp


headzoom.webp
 
Peter1127 said:
Took the head off and there you have it. If you look carefully you can see it goes all the way to the valve guide. . Did take quite some amount of engines apart but this is my first encounter with a cracked head. Didnt see that before because I couldnt be bothered to clean the combustion chambers. Wont make that mistake again. Mistery solved and thanks for your help!


View attachment 1696253

View attachment 1696254
Click to expand...

Well, that sucks, but at least you found the problem.
 
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