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Old October 10th, 2019, 07:19 AM   #1
Brother
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HELP!!!!! Plastic plug on the side of Cylinder Head popped out for the second time.

The little round plug on the top left side of the cylinder head has popped out for the second time (this time while riding, the first was when I was in a parking lot) I honestly have no clue what could cause this??? I thought maybe the crank case breather hose was clogged and it had excess pressure.The first time I checked it, there was no clogging/debris.

Any insight into these engines would be greatly appreciated as this part cant be ordered online as far as I can tell. If someone does know where I can order it, please let me know that too.
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Old October 12th, 2019, 02:46 AM   #2
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My best guess is that it has shrunk and gone hard and the least little bit of pressure causes it to pop out. Never heard of this before. You can plug the hole with the correct replacement part and see if it stays fixed or just use whatever fits in the hole to stop oil leaking out I suppose?
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Old October 12th, 2019, 06:57 AM   #3
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My best guess is that it has shrunk and gone hard and the least little bit of pressure causes it to pop out. Never heard of this before. You can plug the hole with the correct replacement part and see if it stays fixed or just use whatever fits in the hole to stop oil leaking out I suppose?
Unless I'm mistaken, the subject plug is not offered as a replacement part...at least in any US parts fiche. I looked from '88 to '12. An inquiry at a Kawasaki dealer parts department is advisable. This avenue should be explored for availability.

OP will likely need to resort to some sort of sealing adhesive. I'd suggest researching a quality product that will be permanent in nature.

Do your homework, JB Weld, for example, has some new versions out there.
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Old October 12th, 2019, 09:46 AM   #4
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That thing is just a "core plug".

This is a characteristic of every engine is constructed using sand-forms to create the internal passages necessary for coolant and oil flow and other items.

Every sand-cast engine block or head has one or more of these holes that are included in the design to allow quick, easy and complete removal of the sand-form after the casting process is finished.

So yeah, just use something like JBweld to stick it back in there for good.

https://en.wikipedia.org/wiki/Core_plug
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Old October 12th, 2019, 12:13 PM   #5
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Check your crankcase vent to make sure it's not blocked and building up pressure inside there. That's the only time I've ever seen those pop out. Kinked hose where you don't expect is what I'm thinking if the actual vent is clean. Check the whole run. It only ever pops out from excessive pressure.
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Old October 12th, 2019, 01:51 PM   #6
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Check your crankcase vent to make sure it's not blocked and building up pressure inside there. That's the only time I've ever seen those pop out. Kinked hose where you don't expect is what I'm thinking if the actual vent is clean. Check the whole run. It only ever pops out from excessive pressure.
Is this a core plug in the water jacket? I can't imagine the hole opens directly into the crankcase.
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Old October 12th, 2019, 02:24 PM   #7
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Is this a core plug in the water jacket? I can't imagine the hole opens directly into the crankcase.
No, the hole we're talking about is in the camshaft head and the hole itself is located at the base of the camshaft area.

My guess about this particular core plug is that having that hole there: aids sand removal after casting, provides a wash-out path during machining, and maybe even gets used as a pick-up or hold-down point on the assembly line.
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Old October 14th, 2019, 07:01 AM   #8
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Quote:
Originally Posted by greg737 View Post
That thing is just a "core plug".

This is a characteristic of every engine is constructed using sand-forms to create the internal passages necessary for coolant and oil flow and other items.

Every sand-cast engine block or head has one or more of these holes that are included in the design to allow quick, easy and complete removal of the sand-form after the casting process is finished.

So yeah, just use something like JBweld to stick it back in there for good.

https://en.wikipedia.org/wiki/Core_plug
Thank you for the insight. I have a used part coming in to replace the plug. Going to high heat glue it back on so it never comes out while riding again. (Oil spewing out onto my rear tire was no fun at 45mph
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