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Wow expensive mistake, sorry to hear that. What I can add is that the camshaft cap is machined from the factory to adhere to the specified tolerance between it and the camshaft journals. Salvaging spare caps is a crap shoot in itself. If you manage to salvage spare caps, you gotta check for clearances that are within the specified tolerances, (section 5-20 in the service manual). If the clearance is below the specs, then you could hone the cap using a lathe. You'll have to find a machine shop to do this for you. Conversely, if the clearance is above the specified specs, you're back to square one. But the best solutions are to salvage a complete head or buy a new one.

Get a good quality torque wrench. Get both a clicker and beam type torque wrench to compare accuracies. Especially in these critical engine components.

To get the proper torque values, those cam cap bolts require a dry torque. Meaning the bolt and screw holes must be dry and clean. If the threads are wet (oiled) then the torque figures will be roughly 30% more than what is required. Be sure there is no residual oil on the bolt threads and screw holes. Spray 'em down with brake cleaner or a degreaser. Unless specified by the service manual, always clean bolt threads and holes before torqueing. Always torque bolts in the specified sequence for an even force distribution and to minimize warping.

Didn't mean to preach, some tips that should help you out. Good luck.
Preach on brotha..Enjoyable sermon. Can I get an amen?
馃悏
 

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I also wonder if one of your dowel pins might have been cockeyed?
Yep, I was thinking of that too..........

I would say wrong spots, but if you pulled it all apart and did not find anything, they could have been on there off just enough that when any torque was applied it caused them to bind.

Anyway you look at it, that sucks and sorry about that
 

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Wow, it looks like the P/N changed midway for Ninja 400, and the Z400 has the latter part (11008-0967):

HEAD-COMP-CYLINDER1100811008-08861( - EX400GEA37486)
HEAD-COMP-CYLINDER11008A11008-09671(EX400GEA37487 - )

Notice the serial number ranges!

I have S/N 31304 -- so mine seems to be the older part... Two other parts (o-rings) are also different based on serial number ranges...

The crank case (below) and head cover (above) seem independent of serial numbers.
 

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Another possible reason for the cracked cam cap is due to the overtightened sparkplug. It may have fatigued the aluminum cap enough to cause a hair-line crack. And then exacerbated when it was torqued down later on. Would have to see a pic of where the crack is to get a better hypothesis.

EDIT: Nevermind, sparkplug and cam cap aren't mechanically fastened.
 
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Let's see some pics of the damage. I'm curious now. Not sure how it's possible to crack the cap unless it wasn't aligned right and seated. And yes, the cap can be seated by hand actually, just need to align it with the dowel pins. When I took mine off, it was still fully seated even after I removed every screw (sticky/suction effect of the grease they use on the surfaces of the cam journals and the cam cap). Normally you should be able to put it over the cams, and then screw in all the bolts by hand almost to the end, then just use a torque wrench to torque to the right spec.
 

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Discussion Starter · #26 ·
@Rich T @b0Xcrash

Misaligned/jammed dowel pin crossed my mind, too. But the camshaft cap cracked when I was tightening down bolt 2 (going by the torque sequence in service manual 5-20), so I am not so sure. Dowel pins are are underneath bolts 2 and 3. fracture occured between bolts 2 and 6 and indicated by *
18178



Crankshaft Position when installing the camshafts per 5-18:
18179



Intake side camshaft showing shorter timing marks (blue) aligned with cylinder head upper surface. Getting a good angle was difficult, so I put a piece of paper on the cylinder head upper surface for reference.
18180


The only way to see the timing marks on the exhaust side camshaft is to peer through a gap in the fame and hoses. I could not get my camera to focus on the camshaft.


Discussion Thread Recap
-Everyone agrees I have to order a new cylinder head.
-Couldn't find any second hand parts on ebay or from a salvage yard.
-Purchasing a salvage bike is technically possible, but I don't want to mess around with salvage parts especially since I won't know how to do a quality check.

-THANK YOU EVERYONE who took a few moments to read and post their thoughts on this thread! After a really tough weekend I really appreciate all of the input and advice to make sure that I am on the right track and have looked at all the options.

Next Steps
-I am going to order the cylinder head and new gaskets tonight. Cylinder head needs 1-2 weeks lead time prior to shipment, so I will have a bit of down time. I will still be reading and posting here.
-Add fuel stabilizer to the siphoned gas
-Do I need to do anything to the bike since it's going to sit for a few weeks? Especially the empty gas tank? Battery is disconnected and every intake/exhaust/exposed cylinder head is either covered with painters tape or lint free cloth.
-Clean up and organize the garage.
-Read and Re-read the service manual and @Watcher905's sermon about 1000 times.
 

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Sitting a few weeks is nothing... Just make sure nothing drops into the engine... (And probably don't kick up lots of dust sweeping the garage unless the engine is covered.)

I'm having a hard time imagining that cracking without something acting as a fulcrum... Does the crack go all the way thru the cap?

The thing to keep in mind next time is to make sure the cap seats properly before torqueing anything to any significance or to spec.
 

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@Rich T @b0Xcrash

Misaligned/jammed dowel pin crossed my mind, too. But the camshaft cap cracked when I was tightening down bolt 2 (going by the torque sequence in service manual 5-20), so I am not so sure. Dowel pins are are underneath bolts 2 and 3. fracture occured between bolts 2 and 6 and indicated by *
View attachment 18178


Crankshaft Position when installing the camshafts per 5-18:
View attachment 18179


Intake side camshaft showing shorter timing marks (blue) aligned with cylinder head upper surface. Getting a good angle was difficult, so I put a piece of paper on the cylinder head upper surface for reference.
View attachment 18180

The only way to see the timing marks on the exhaust side camshaft is to peer through a gap in the fame and hoses. I could not get my camera to focus on the camshaft.


Discussion Thread Recap
-Everyone agrees I have to order a new cylinder head.
-Couldn't find any second hand parts on ebay or from a salvage yard.
-Purchasing a salvage bike is technically possible, but I don't want to mess around with salvage parts especially since I won't know how to do a quality check.

-THANK YOU EVERYONE who took a few moments to read and post their thoughts on this thread! After a really tough weekend I really appreciate all of the input and advice to make sure that I am on the right track and have looked at all the options.

Next Steps
-I am going to order the cylinder head and new gaskets tonight. Cylinder head needs 1-2 weeks lead time prior to shipment, so I will have a bit of down time. I will still be reading and posting here.
-Add fuel stabilizer to the siphoned gas
-Do I need to do anything to the bike since it's going to sit for a few weeks? Especially the empty gas tank? Battery is disconnected and every intake/exhaust/exposed cylinder head is either covered with painters tape or lint free cloth.
-Clean up and organize the garage.
-Read and Re-read the service manual and @Watcher905's sermon about 1000 times.
Are you going to buy a complete head assembly then?? How much is that going to cost? How much to buy your current one with the cracked cap?
 

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Discussion Starter · #29 ·
Sitting a few weeks is nothing... Just make sure nothing drops into the engine... (And probably don't kick up lots of dust sweeping the garage unless the engine is covered.)
Good to hear everything will be fine sitting for a few weeks. And yes, I have the engine covered and a rolled up lint free cloth in the camshaft chain tunnel.

I'm having a hard time imagining that cracking without something acting as a fulcrum... Does the crack go all the way thru the cap?
Yes, the crack goes all the way through. I agree that something had to act as a fulcrum. Cams are properly aligned, so the cap didn't catch on cams. And I didn't find a loose bolt (triple checked with flashlight and magnet) that could have wedged between the cam cap and cylinder head. Right now my best guess it that the cam cap got stuck on the dowel pin underneath bolt 3, and cracked when I was tightening bolt 2 (Furthest point from bolt 3).

The thing to keep in mind next time is to make sure the cap seats properly before torqueing anything to any significance or to spec.
Agree. I will be working with a much lighter touch in the future.

@sbk1198

New cylinder head plus tax is $1200 (at least I got free shipping!). I may need to reuse some bolts, so I will be happy to sell off the old cylinder head and cracked cam cap after the new one is installed. Otherwise, I will mount the cracked cam cap to my wall as a reminder.

Were you thinking of repairing and reusing? JB welding the cracked cam cap back together did cross my mind, but since both parts are machined together with high tolerances, I figured the repair would have a high chance of just not working quite right.
 

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Good to hear everything will be fine sitting for a few weeks. And yes, I have the engine covered and a rolled up lint free cloth in the camshaft chain tunnel.



Yes, the crack goes all the way through. I agree that something had to act as a fulcrum. Cams are properly aligned, so the cap didn't catch on cams. And I didn't find a loose bolt (triple checked with flashlight and magnet) that could have wedged between the cam cap and cylinder head. Right now my best guess it that the cam cap got stuck on the dowel pin underneath bolt 3, and cracked when I was tightening bolt 2 (Furthest point from bolt 3).



Agree. I will be working with a much lighter touch in the future.

@sbk1198

New cylinder head plus tax is $1200 (at least I got free shipping!). I may need to reuse some bolts, so I will be happy to sell off the old cylinder head and cracked cam cap after the new one is installed. Otherwise, I will mount the cracked cam cap to my wall as a reminder.

Were you thinking of repairing and reusing? JB welding the cracked cam cap back together did cross my mind, but since both parts are machined together with high tolerances, I figured the repair would have a high chance of just not working quite right.
Possible to repair/reuse depending on what I see in person. Hard to really make a judgement from a few pics. But mainly because I want a stock cylinder head that hasn't been ported yet. I had mine ported but the guy that did it did a pretty shitty job IMO, so I want to get a stock one, put it in my bike, do a baseline dyno run, then have someone else port it and dyno it again. It would be a long term project since I don't have the time to do all of that right away, but still.

You could also just buy another complete engine off ebay for probably around $800-$900, then sell your current one for less due to the broken cam cap. That way it would only cost you a few hundred bucks in the long run and all you have to do is swap the engines rather than open it up. Less time and less money....just a thought.
 

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Discussion Starter · #31 ·
Possible to repair/reuse depending on what I see in person. Hard to really make a judgement from a few pics. But mainly because I want a stock cylinder head that hasn't been ported yet. I had mine ported but the guy that did it did a pretty shitty job IMO, so I want to get a stock one, put it in my bike, do a baseline dyno run, then have someone else port it and dyno it again. It would be a long term project since I don't have the time to do all of that right away, but still.
If you can repair and reuse that would be cool. It's a clean crack all the way through. Here is a slightly better pic of the damage if that helps you make your decision. If you think you might still be interested, we can try and figure out details so you can see it in person after I get the new one installed.

18189


You could also just buy another complete engine off ebay for probably around $800-$900, then sell your current one for less due to the broken cam cap. That way it would only cost you a few hundred bucks in the long run and all you have to do is swap the engines rather than open it up. Less time and less money....just a thought.
Yes, I did see a whole z400 engine on ebay. Cost plus shipping is $1300. One concern I have is if there are any issues with the ebay engine, I won't be able to diagnose by myself and could find myself with an even bigger problem...and without the knowledge or experience to really fix it. After a few more sparkplug replacements I might have the confidence to order an engine off ebay and rebuild if necessary...but not yet. 馃ぃ
 

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If you can repair and reuse that would be cool. It's a clean crack all the way through. Here is a slightly better pic of the damage if that helps you make your decision. If you think you might still be interested, we can try and figure out details so you can see it in person after I get the new one installed.

View attachment 18189



Yes, I did see a whole z400 engine on ebay. Cost plus shipping is $1300. One concern I have is if there are any issues with the ebay engine, I won't be able to diagnose by myself and could find myself with an even bigger problem...and without the knowledge or experience to really fix it. After a few more sparkplug replacements I might have the confidence to order an engine off ebay and rebuild if necessary...but not yet. 馃ぃ
I just checked now cuz I didn't believe it and wow those prices are high! Only a few options and cheapest is $1300 like you said. That's crazy! I remember seeing them going for much lower a while ago when I was looking just for shits and giggles. I struggled to get like $700-$800 for a zx6r engine when I parted out my old ZX6R that was in good shape with less than 5k miles, after like 7 months of being listed for sale! And these mofos are asking $1300-$2000 for a ninja 400 engine?? Unreal! I've sold Ducati and Aprilia engines for $2000! lol

Regarding that cam cap, i'm just not convinced that the part where it cracked is really needed. It's basically just a bridge connecting the parts that do matter. So either cutting it off completely or JB-welding it, or actually welding it would probably all be just fine. So I would attempt to re-use it. But if not, then like I said, I just want a stock cylinder head for my future project.
 

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Discussion Starter · #33 ·
I just checked now cuz I didn't believe it and wow those prices are high! Only a few options and cheapest is $1300 like you said. That's crazy! I
I'm guessing it's the pandemic driving up prices. Ever since everything went into lockdown, my local bike shop has only been able to keep their showroom half full, and they are on a five week backlog for service.

Regarding that cam cap, i'm just not convinced that the part where it cracked is really needed. It's basically just a bridge connecting the parts that do matter. So either cutting it off completely or JB-welding it, or actually welding it would probably all be just fine. So I would attempt to re-use it. But if not, then like I said, I just want a stock cylinder head for my future project.
I am so paranoid about doing an incomplete/incorrect fix and making things even worse. Not brave enough to JB weld it back together just yet. Although not being able to ride for a few weeks while waiting for the cylinder head might change my mind...

Reusing Gaskets?

New cylinder head has been ordered, but all of the associated gaskets are listed as unavailable or sold out. I'm not too concerned about reusing the gasket for the cylinder head cover--it's fairly thick rubber, in great condition, and not in a high pressure part of the engine.

But I am a little more concerned reusing the gasket that goes between the cylinder head cover and the engine cylinders. Any suggestions for what kind of gasket mat I can buy to cut my own?
 

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I'm guessing it's the pandemic driving up prices. Ever since everything went into lockdown, my local bike shop has only been able to keep their showroom half full, and they are on a five week backlog for service.



I am so paranoid about doing an incomplete/incorrect fix and making things even worse. Not brave enough to JB weld it back together just yet. Although not being able to ride for a few weeks while waiting for the cylinder head might change my mind...

Reusing Gaskets?

New cylinder head has been ordered, but all of the associated gaskets are listed as unavailable or sold out. I'm not too concerned about reusing the gasket for the cylinder head cover--it's fairly thick rubber, in great condition, and not in a high pressure part of the engine.

But I am a little more concerned reusing the gasket that goes between the cylinder head cover and the engine cylinders. Any suggestions for what kind of gasket mat I can buy to cut my own?
You're talking about the head gasket?? If so, don't mess around making your own. That's a pretty critical and specialized gasket. See if Norton has any in stock.
 

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Discussion Starter · #35 ·
You're talking about the head gasket?? If so, don't mess around making your own. That's a pretty critical and specialized gasket. See if Norton has any in stock.
馃ぃ More encouragement for me to NOT try and repair the camshaft cap cover on my own.

Norton has a few different ones in stock. I'm looking at this one, which doesn't need a special gasket spray.

Any tips for prepping the engine cylinder surface? I am thinking of wiping it down with a rag wetted with degreaser. I want to use as little degreaser as possible to avoid getting anything on the pistons.
 

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馃ぃ More encouragement for me to NOT try and repair the camshaft cap cover on my own.

Norton has a few different ones in stock. I'm looking at this one, which doesn't need a special gasket spray.

Any tips for prepping the engine cylinder surface? I am thinking of wiping it down with a rag wetted with degreaser. I want to use as little degreaser as possible to avoid getting anything on the pistons.
Yeah that's the OEM equivalent for the head gasket. Once you see it in your hands you'll know that it's not something you can just make yourself out of something lol It's a metal gasket that has a thin layer of some type of polymer on both sides, which is what helps with sealing. I simply took the old one (stock one) off and put the new one in. That's it. No surface prepping because there wasn't a liquid gasket on it, like what you would do on a clutch cover for example which you have to clean up and re-apply.

I can't say with 100% certainty that it's the proper procedure of replacing a head gasket but that's what I did and it hasn't leaked yet lol

I got the same brand, but the thinner version from Norton.
 

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Am I right that the middle part of the cap doesn't actually touch anything? It just controls spray/drip around the cams? Seeing your crack now, I am wondering if you can't just take it to a weld shop and tack the top together and be good... The actual journals are far left and far right and still solid, nowhere near the crack -- I don't think the crack is under any real stress in operation -- which might explain why that section was so delicate... Did I misunderstand what is where?
 

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Discussion Starter · #39 ·
@Rich T

Here is a close up of the underside. You are correct that the crack does not touch the cam. Any concerns about a repair affecting how the unit is torqued down? This is far outside my expertise.

18225
 

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I'm also learning to wrench, so this is good info to share. Thank you for letting us other newbs in on your mistakes so we might avoid the same ones. I'll be doing my clutch springs and plates soon and will also be installing and exhaust and the velocity stacks. I'd like to avoid mistakes so I'm not missing prime riding time.

Hope you get this situation figured out quickly so you can also get back in the saddle.
 
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