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.

Project: Engine Drop and Maintenance

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

 

T

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.

Project: Engine Drop and Maintenance

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

thanks for this I only changed it because a spark plug busted in the head and I needed a new head, so I figured while I was down there might as well changed the gaskets,

It’s not a hassle changing it lol! It’s just a motorcycle! I cannot take it with me when I leave this precious world! But I will one day get her running perfectly! I’ll upload some pictures of what else I can see,

I cleaned everything
before placing the gaskets

should be a perfect seal! Still getting overheating temp light! Lol

 

Update
I have found 2 spots leaking coolant, first spot is the left hand side radiator hose leaking quite a bit, and than I found this platform on the head in picture also leaking

(the hose that’s attached to the nozzle on the piston head)

Hopefully this will fix the overheating, obviously losing coolant is not a good cause

I’ll update this page tonight when I get off work and take her for a ride.

 

The O-rings in those metal coolant lines go bad so easily. I have a bunch of spare ones on hand for any maintenance on this bike for that reason. Helps to scrub up the fittings too so they seal perfectly, and I use a dash of silicone grease on them too for clean install.

-Mike

 

I took her on a ride again, no luck, temp light came on, leaks didn’t fix it, gonna check all gaskets again,

all the coolant sucked into the overflow tank-and boiled,

 

Hey man!

Sorry for being offline for a bit - it was trackday weekend last weekend, shredded my gixxer out there.

At home, if you have some supplies you can get away with a good cylinder head surface prepping. What you want to do is a very light surface lapping via wet sanding.

I used a piece of glass as my flat surface. You need to verify with a machinist ruler or similar that the glass is at least as flat as the flatness spec for your cylinder head. I forget what the spec is on the 300, but my piece of glass was immeasurably flat for me (I couldn't detect any warpage with any tools I had). So I took my cylinder block (off the engine of course) and used 800-2000 grit wet/dry sandpaper mounted on my piece of glass, and then ordinary water running on the sandpaper. Start with 2000 grit, and if it is too slow or your head has too much surface damage, step down to 1500, 1000, or 800 if its super bad, but be careful because that might remove too much material.

Just run the head in a figure 8 pattern on the glass and sandpaper with running water, rotating the work piece every few cycles. The weight of the cylinder block or cylinder head should be enough to get even surface cleaning. On some cylinder heads, usually high performance engines, the valves actually stick out past the cylinder head mating surface, so this does not work if that is the case, you'd need to remove all the valves prior to lapping the cylinder head. My GSX-R750 was that way, so when I did that head gasket, I had to remove all 16 valves to lap the cylinder head.

When you are done, it should be a nearly flawless surface once you've wiped off the dust and debris. Make sure you get all the water off the cylinder head or block because steel parts can rust. So usually compressed air, put the part in front of a heater, and then some WD-40 to ensure no rusting prior to re-installation. You could also use the WD-40 as your wetsanding lubricant, I have had success with that too, you just need a lot of it and it gets messy.

Then of course once you've lapped both the cylinder block and the head mating surface, put some brake cleaner on a paper towel and wipe everything off the surface, all oils and WD-40 or anything else, and clean the whole part inside and outside, and one final blast with compressed air before final assembly to ensure you have no FOD in the mating surfaces.

Then crank down the new head stud bolts and washers to assemble it. And yes, new ones are required on the 300, they are TTY bolts.

I hope this helps! Post pics of the engine pieces up!

-Mike

 

Slapping my new red fairings on while I’m at it, haven’t taken the top off of the head yet, thinking about taking the head to a nearby shop,

should I bring the piston barrel too? Will they also flatten that and port the barrel?

 

If you aren't going to do the work on the block or the head, then yeah bring them both to the shop. Just make sure your piston ring gap is maintained after a hone if you do that to the block. Your shop will know how to do this if you bring your pistons and rings. Might as well get new rings if you've got this all out - no extra effort.

-Mike