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Discussion Starter · #41 · (Edited)
Don't know. That's why I'm asking lol.
I don't think it matters what rad cap you use. The system is still pressurized when heated, the culprit is the bloody OEM seal.

EDIT: Off topic, what's interesting is that Kawa did not redesign the seal, but the entire cylinder head is replaced with a new part number for the 2020-21 models. I have no idea when they did this or what if anything they changed.
 
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I don't think it matters what rad cap you use. The system is still pressurized when heated, the culprit is the bloody OEM seal.

EDIT: Off topic, what's interesting is that Kawa did not redesign the seal, but the entire cylinder head is replaced with a new part number for the 2020-21 models. I have no idea when they did this or what if anything they changed.
I doubt they changed anything other than the part number. I laid into Kawasaki about having to spend almost a grand to solve the false nuetral issues that came from the factory. I can't believe that Kawasaki has not changed that coolant seal.
 

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Well, so far: Did tires, fork brace, new springs, new fork oil 15w, cleaned bmc air filter, replaced fuel filter, adjusted valve shims as the exhausts needed adjustments. Down to this level, getting ready for the cylinder header removal and gasket replacement. A miss ordered gasket for the header at the upper/lower connection meant a delay. Close. so close…

18920
 

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Well, so far: Did tires, fork brace, new springs, new fork oil 15w, cleaned bmc air filter, replaced fuel filter, adjusted valve shims as the exhausts needed adjustments. Down to this level, getting ready for the cylinder header removal and gasket replacement. A miss ordered gasket for the header at the upper/lower connection meant a delay. Close. so close…

View attachment 18920
Man where do you even start taking it apart from that point lmao. Hands down to all of you, really.
 

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Got my final gasket, so took the full top end off last night. Time to clean the pistons tonight. Not sure if this is standard build up, assuming so based on others. maybe .2 to .3mm buildup. I am guessing the buildup can be because of constant high rpm? The N400 is happiest above 7k. ;)

18988


18989

And that nasty gasket. Kink on the left side clearly the problem.
 

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Got my final gasket, so took the full top end off last night. Time to clean the pistons tonight. Not sure if this is standard build up, assuming so based on others. maybe .2 to .3mm buildup. I am guessing the buildup can be because of constant high rpm? The N400 is happiest above 7k. ;)

View attachment 18988

View attachment 18989
And that nasty gasket. Kink on the left side clearly the problem.
Please open a case with Kawasaki and share your pics so Kawasaki is aware of the problem, the more people who alert Kawasaki the better the chance they will fix it.

I opened a case regarding the false nuetral issues.
 

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Please open a case with Kawasaki and share your pics so Kawasaki is aware of the problem, the more people who alert Kawasaki the better the chance they will fix it.

I opened a case regarding the false nuetral issues.
I agree, I think everyone who had this issue should contact Kawasaki Japan via their website or make sure they get this message. Unbelieveable this stuff happens.
 

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Cleaned it all up, ready for re-assembly starting tonight...
19000


19001


I started to cleaning with brake cleaner, thinking I would use a sharp plastic tool to scrape it all off. Ha! Quickly moved to a steel brush. Then moved to a screwdriver to carefully chip it all off. Brake cleaner and the screwdriver worked best for the Piston heads. I stayed with the metal brush for the valves, not wanting to even accidentally put a scrape gouge in them.

Ready to re-assemble!

FYI, thanks all here for the info and write-up. Definitely helped with confidence, bolstering the details of the manual which is reaaaally good.
 

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Done! Finally assembled after all the time and effort. The coolant gasket is in, all bits are assembled, and the moto started up and sounds fabulous. There are a few notes that need mentioning, most specifically the cam chain and cam shaft installation.

There seems to be an issue in the manual about the camshaft timing setup. The removal happens at the “|” mark. This mark indicates when both cylinders are dead even. Then immediately following it talks about the installation, which seems to be at the same mark. However, later it mentions setting the camshafts at the 2|T mark. The manual does a good job of outlining the gear settings, so that part is pretty easy. It’s the cylinder marking that seems to be the problem.

The manual outlines the camshaft settings at 2|T. Except the problem is if installing the camshafts at this mark, and using the manual settings, then the cylinder 1 exhaust lobes have some positive contact with the valve buckets, and causes a slight lifting to the camshaft. It would work, but not ideal for finishing the assembly.

So, I installed at the 2T mark to line up the cams properly. Then rotated slightly to release the valve spring tension on the lobes. Then installed the camshaft cap. This worked great.

I had originally installed at the | mark, and when giving the crank a slow turn to test, it stopped where the second cylinder top was about to show, because the lobes clearly were opening the exhaust valves on cylinder 2, causing a bind.

So, mark the cams at the | setting for easy installation, or follow the manual at the 2|T mark knowing you will have just a little valve lifting in the 1st cylinder exhaust valves.

So glad all that is done. It purrs again. It took me three weeks from start to finish since I had to order the coolant gasket once noticed, and a few more bits since I was going deep.

The other reason to do this job is to clean your pistons. Surprised me at the buildup at 18k miles.

19031

Back together and stretching its legs with all the work. New Dunlop Q3+ tires, fork springs and 15w oil, plugs, air filter cleaning, fork brace install, valve adjustments and that @#$&*( coolant gasket.
 

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Discussion Starter · #50 ·
Done! Finally assembled after all the time and effort. The coolant gasket is in, all bits are assembled, and the moto started up and sounds fabulous. There are a few notes that need mentioning, most specifically the cam chain and cam shaft installation.

There seems to be an issue in the manual about the camshaft timing setup. The removal happens at the “|” mark. This mark indicates when both cylinders are dead even. Then immediately following it talks about the installation, which seems to be at the same mark. However, later it mentions setting the camshafts at the 2|T mark. The manual does a good job of outlining the gear settings, so that part is pretty easy. It’s the cylinder marking that seems to be the problem.

The manual outlines the camshaft settings at 2|T. Except the problem is if installing the camshafts at this mark, and using the manual settings, then the cylinder 1 exhaust lobes have some positive contact with the valve buckets, and causes a slight lifting to the camshaft. It would work, but not ideal for finishing the assembly.

So, I installed at the 2T mark to line up the cams properly. Then rotated slightly to release the valve spring tension on the lobes. Then installed the camshaft cap. This worked great.

I had originally installed at the | mark, and when giving the crank a slow turn to test, it stopped where the second cylinder top was about to show, because the lobes clearly were opening the exhaust valves on cylinder 2, causing a bind.

So, mark the cams at the | setting for easy installation, or follow the manual at the 2|T mark knowing you will have just a little valve lifting in the 1st cylinder exhaust valves.

So glad all that is done. It purrs again. It took me three weeks from start to finish since I had to order the coolant gasket once noticed, and a few more bits since I was going deep.

The other reason to do this job is to clean your pistons. Surprised me at the buildup at 18k miles.

View attachment 19031
Back together and stretching its legs with all the work. New Dunlop Q3+ tires, fork springs and 15w oil, plugs, air filter cleaning, fork brace install, valve adjustments and that @#$&*( coolant gasket.
Glad it worked out for ya!

Regarding the cam shafts install, the way I understood it was to install them exactly the same way as you removed them. Either by marking them with paint or sharpie or taking pics beforehand. The crankshaft must remain in the same "|" position.
Then install the cam chain, cam chain guides, the cam chain tensioner and cam caps. This way, no valves will be lifted by any of the cam lobes.

Next, when the crank is turned to the "2|T", the cam shafts with their "IN" and "EX" indents are automatically lined up. Essentially, the "2|T" position is a visual confirmation that everything is timed correctly.
 
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Glad it worked out for ya!

Regarding the cam shafts install, the way I understood it was to install them exactly the same way as you removed them. Either by marking them with paint or sharpie or taking pics beforehand. The crankshaft must remain in the same "|" position.
Then install the cam chain, cam chain guides, the cam chain tensioner and cam caps. This way, no valves will be lifted by any of the cam lobes.

Next, when the crank is turned to the "2|T", the cam shafts with their "IN" and "EX" indents are automatically lined up. Essentially, the "2|T" position is a visual confirmation that everything is timed correctly.
Watcher, yes. If I had been more meticulous about the removal, I would have marked the cams at the “|” spot. But somehow this is the only point at which I seem to have drifted in the process! So, from scratch with the manual and this write up. Also just pointing out that if someone boneheads the removal, all is not lost! Was actually quite a fun tear down and rebuild. Next time will definitely be easier and faster.
 

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As far as submitting some constructive criticism direct to Kawasaki:

My online submittal:
2018 kawasaki ninja 400 please update!

I am currently suffering through the coolant gasket replacement on my 2018
kawasaki ninja 400 abs krt. It is a known issue. The fix involves a LOT of
labor. This should not be a failure point. It still has not been fixed on
2021 models! Come on Kawasaki! It is well over a $1,000 USD repair in labor
due to the time to fix. Then several hundred dollars in gaskets and parts.
This is a ridiculous failure point with an easy fix. talk to Norton
Motorsports. Their gasket is great. Excellent solution. But still, the time
to fix is excruciating.


And their response. About what you would expect, and maybe they get enough pressure to do something, someday...

Thank you for contacting us.

Thank you very much for your report.
We have received your request as a valuable opinion.
So we would like to use it as a reference for future product development.

We look forward to your continued patronage of our company.

Thanks and best regards.

Web administrator

Motorcycle & Engine Company
Kawasaki Heavy Industry,Ltd

Had to plug Norton, as that gasket is longevity inspiring. Quality engineering.
@Norton-Motorsports.com
 

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And thought I'd share some more of the pictures of the maintenance adventure:

19078

Cleaned and ready to rebuild the top end 'cake'.

19079

Lubed, gasket ready for coolant and header assembly.

19080

Used existing bolts for assembly line up. Didn't order two up, and the bolt diameter/thread size is not available at my local hardware store...
Ready for piston insertion.

19081

Piston inserted, first layer seated.

19082

Header on, gasket confirmed in proper place, bolts finger tightened, ready for torque'ing.

19083

Torqued.

19084

Cams installed and everything buttoned up.

Feels good on its first hard rip...
19085


And all that work, for a very happy rear tire story...
19086

The suspension upgrades for the front, and the shock settings ala Dave Moss, and the rear tire tells the story of all the love. The N400 sure does purr and hold a great line.
 

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And thought I'd share some more of the pictures of the maintenance adventure:

View attachment 19078
Cleaned and ready to rebuild the top end 'cake'.

View attachment 19079
Lubed, gasket ready for coolant and header assembly.

View attachment 19080
Used existing bolts for assembly line up. Didn't order two up, and the bolt diameter/thread size is not available at my local hardware store...
Ready for piston insertion.

View attachment 19081
Piston inserted, first layer seated.

View attachment 19082
Header on, gasket confirmed in proper place, bolts finger tightened, ready for torque'ing.

View attachment 19083
Torqued.

View attachment 19084
Cams installed and everything buttoned up.

Feels good on its first hard rip...
View attachment 19085

And all that work, for a very happy rear tire story...
View attachment 19086
The suspension upgrades for the front, and the shock settings ala Dave Moss, and the rear tire tells the story of all the love. The N400 sure does purr and hold a great line.
Maybe I missed it but was the valve adjustment out much?
 

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@Tracy , valve adjustment breakdown:

Going from Cylinder 1 to 2, left to right.
Exhaust1: .23, range is .25 to .31
Exhaust2: .25
Exhaust3: .24
Exhaust4: .25
Intake1: .15, range is .13 to .19
Intake2: .15
Intake3: .13, adjusted to .18. Prefer .1 inside range instead of on the outside of the range.
Intake4: .15

Adjusted all exhaust valve clearances and one intake. This is apparently standard expectations.
 

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Hey man thanks. I'm at 22k mi. So I know its in my very near future. I am happy to know that they were still close in tolerance rather than way out.
🐉
 
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