Hey! Welcome to the forums!
I think I can help you here. I have replaced the head gasket on my 300 and other bikes as well, and so far I am (knock on wood) 100% on my head gaskets working after install.
I've got a lot to say, so sorry if I ramble.
Good thing you have the shop book, it is absolutely required for this operation. Also, good on you for taking matters into your own hands! Most folks give up if it's not an oil change or chain cleaning.
Can you tell us a bit more about the bike? I think there is some other info that might help us help you, and I am curious as to how you arrived at the conclusion you needed to replace the head gasket. How many miles on the bike? General history about it? How do you ride it? Stay on top of oil and coolant changes? Does it run okay? What kind of coolant and oil do you use?
What was the proximate event to you deciding the bike needed a new head gasket? Did you see bubbles coming out the radiator cap with the engine running? Have you performed a sniffer test on the radiator to prove that combustion products are escaping into the radiator?
Unfortunately to say, unless you did those last few tests I just mentioned and they had positive results, your head gasket replacement was likely entirely unnecessary.
For what it's worth, I (nor anyone I have ever met) needed to actually
replace the head gasket in their bike because the head gasket has failed. They are usually just replaced out of necessity due to the proximity of other repairs or work. For example, when I replaced the head gasket on my 300, I did it because it was part of another repair job. In my case, I had moderate blowby in my engine at around 40,000 miles. So in my piston and cylinder service I replaced the head gasket (and many others).
I quite firmly believe that in most cases, when a normal motorcyclist has overheating issues with their motorcycle, it is
not due to the head gasket failing. 95% of the time, overheating is usually radiator/cap/coolant/thermostat/water pump related, or a leak in the cooling system. I say this too because you are right, the head gasket is indeed multi-layered. These are called MLS gaskets, due to their multi-layer steel construction. And the key takeaway about MLS gaskets is that they are basically the best type of gasket for cylinder heads, bar none. When installed correctly, they essentially last forever, and never leak, and may even retain a proper seal even if you overheated the engine and it warped the cylinder or head. They are quite fantastic.
In regards to how to install it, you are also right; the manual does not say very much, nor to really any manuals. You do quite simply 'put the gasket on' and then put the cylinder head on. But the part that the manual doesn't say is how clean the cylinder and cylinder head surfaces need to be. You need to remove every single tiny scrap of old gasket or debris off the mating surfaces. I went so far as to lap the surfaces with a flat surface and wet sand paper. If you put the head gasket on parts that didn't look basically new, it will have a very hard time sealing. And indeed there is
no sealant or adhesives used in the application of a head gasket. Nothing on it, nothing in the layers, nothing. Dry.
I would also have recommended you remove the engine to do this work, it's really only the chain and 2 large bolts at the back and a bunch of electrical plugs if you've already got the head off. I would also recommend a valve clearance adjustment, and new gaskets all around for everything.
Here is a link to the thread I made when I did my engine maintenance, it may serve you well. It was a learning experience for me at the time, so some of your questions may be answered there preemptively.
Hey fellas! Figured I'd start a thread for this, move it if needed. My '14 N300 with 40k+ miles, a lot of commuting, hard riding, track days, and some people learning on it needs some real love and care. It runs pretty good, it shifts a little crunchy, a bit of lash has developed in the...
www.kawasakininja300.com
If you do the engine rebuild right, you should be able to just pour coolant and oil in and it should just work. There is no malfunctions associated with a proper install. So if you're still having coolant issues after the work, you will probably need to do it again unfortunately.
Sorry to be the bringer of bad news. On the bright side, I will answer any questions you have and help you get this working if that's what you'd like! We are here to help!
Mine has 60,000 miles on the clock and runs like a champ, in fact I crashed it last week and I will fix it up and bring it to the track again this weekend. Awesome bikes.
I hope this helps. Seriously, read my other thread as much as you can, I essentially documented the whole process.
-Mike
