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Discussion Starter · #1 · (Edited)
Got in way over my head with a sparkplug replacement and ended up with a cracked Camshaft cap. Looks like I can't order this part on it's own and I will need an entire new engine top end.

Am I correct in thinking that the whole top end has to be replaced?

I am looking at an entirely new top end (HEAD-COMP-CYLINDER OEM part 11008) and head gasket. Can I reuse the old camshafts? Any advice appreciated.




In case you are wondering how one goes from a spark plug replacement to a cracked camshaft cap...

I am learning to wrench on my own, and the 7600mile service interval came up for my z400. Time to replace the sparkplugs. Removed the fuel tank and airbox just fine. Replaced the air filter while I was in there. Took out the old sparkplugs. Went to torque down the new sparkplugs and misread in lbs as ft lbs in the service manual. Snapped the sparkplug. Could not remove it from where it sat. So I disassembled the entire engine top end. Managed to get out the plug with a drill and E/Z out. New spark plug threads in just fine. That was Saturday.

Start reassembling the bike on Sunday. Everything is going back together, if a bit slowly. Start putting on the camshaft cap. Everything is tightening down just fine by hand, and I am waiting for the cap to fully seat before breaking out the torque wrench. Apparently Camshaft covers aren't supposed to be fully seated. Camshaft cover cracks. Sad Weekend. Learning to wrench on your on can be very expensive indeed.

It's my first bike, so strong emotional attachment. Will get this thing back and running no matter what.

[Edit: Camshaft covers are supposed to be fully seated against the cylinder head. I figure this out later in the thread, but I am adding this edit here so someone does not leave this thread misinformed]
 

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2017 Suzuki GSXR1000 2010 Suzuki GSXR600 x2 2018/19 N400
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sorry to hear this happened,BUT spilled milk at this point,there was no need to change the plugs with so little miles.did the bike start and run great?
 

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Discussion Starter · #4 ·
@jetpilot01 Yes, the bike started and ran great. Old Plugs were a but sooty, but otherwise looked fine. I will try and remember that for the future. Thanks. Was trying to follow recommended service intervals...

@Tracy Thanks for the suggestion. I tried searching a bunch of OEM parts dealers (including Partzilla and Babbitts), but I can't find the camshaft cap as an individual part. According to this car forum, Camshaft caps are machined and sold together with a head assembly. Camshaft bearing cap replacement Of course, that link is extent of my engine head assembly knowledge, so happy to hear from someone more knowledgeable.
 

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2017 Suzuki GSXR1000 2010 Suzuki GSXR600 x2 2018/19 N400
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I have 9k on my N400R and when I pulled the head to install thin head gasket,plugs where a beautiful tan color (bike is tuned) my point is if it's not broke why fix it !! there are guys with 20k on their plugs and bikes run perfect ! well now at least you have the knowledge how to perform that kind of work ! hopefully you'll never have to do it again !!! no need to torque speakr plugs,1st time get them snug and then 1'4 turn to crush the rings
 

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Discussion Starter · #6 ·
@jetpilot01 Thanks and Yes, I did learn quite a lot this weekend! Now that I have gone through all the steps of taking apart the engine top end, I'm not too intimidated to do it again :)

1/4 turn to crush the rings. I will remember that for next time.
 

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Glad you are learning this, sorry for the (one-time!) lesson! :)

From the kawi parts diagram, attached, you appear to be correct -- they are machined and sold together as 11008/A.

The service manual also says: NOTE The camshaft cap is machined with the cylinder head, so if a new head is installed, use the cap that is supplied with the new head.

(I assume that goes both ways, and applies to the upper chain guide as well?)

Have you considered a salvage yard, where you can get both (all three -- is the cap technically two pieces with the upper chain guide also machined to the head?) for maybe half the new price or less?

From a wrecked bike with low miles should be fine...

-- Rich

PS I would certainly think you can reuse your camshafts -- not sure where the caps cracked exactly, if they might have damaged the journal -- the caps are aluminum and the camshaft is steel, so it seems unlikely the camshaft suffered in the incident. Since there is typically no metal-metal contact in a journal bearing, I'd doubt the aluminum was significantly hardened, unlike the cylinder walls. You could look for scratches on the camshaft, and plastigauge after assembly to be sure...

PPS one last thing:

Apparently Camshaft covers aren't supposed to be fully seated.
Not sure what you mean by this... When the cap is placed on the camshaft, it won't fully seat because some of the valve springs offer some resistance to some cams. You'll tighten the cap slowly and evenly (after putting moly solution on the journals and cams) and a few valves will open under the pressure of a light (!) torque and the cap will fully seat. Only once the cap is fully seated will you torque the cap to spec -- definitely don't go anywhere near full torque spec until the cap is seated -- it should only require inch-pounds to get the cap seated (opening some valves)!

18165
 

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Discussion Starter · #8 ·
@Rich T Thanks for the conformation that I do need to get everything as a unit.

Good suggestion to check out the local salvage yards. I am calling around to places within about one day's drive. Although I do worry that pulling parts from a salvage bike is going to be more work and more opportunity to create new problems, given my inexperience.
 

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You will not find many motorcycle salvage yards open anymore. Everybody is selling parts on Ebay motors. I found this one, which includes the cam caps (you call covers), and even includes the valve cover. 2018 18 19 20 KAWASAKI NINJA 400 EX400 ENGINE CYLINDER HEAD M80 | eBay

The reason why you have to buy the whole cylinder head is that the head, with the caps installed is line bored to make sure the holes for the cams are in perfect allignment.
 

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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.
 

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Discussion Starter · #12 ·
Apparently Camshaft covers aren't supposed to be fully seated.
Not sure what you mean by this...
Here is a pic showing gap I was talking about between camshaft cap and cylinder head. (Pic taken from ebay listing provided by @McRider ). I now assume that this gap needs to be there?


18167


@McRider

Can confirm motorcycle salvage parts are hard to find. Called around a bunch of places about one day's drive from where I live and couldn't find anything.

I did find some crashed bikes on auction a few days drive away, but I think that will be way more trouble than it is worth for me.

Thanks for sharing the Ebay listing, but it looks like N400 part number (OEM part 11008-0886 for '18, '19, and '20 N400) doesn't match Z400 part number (11008-0967). So maybe some minor differences between the engines?

I didn't have any luck searching for Z400 engine cylinder head on Ebay.

@Muchacho22

Snapped at the threads.

BTW, your plugs look great!
 

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Discussion Starter · #13 ·
@Watcher905

Thanks for the sermon! Not having a sense of what is right and what is not got me into all of this trouble. So I do appreciate the specific advice.

After all, I only made two mistakes, but wow, were they stupid! And if I had a better sense of things, I probably would have at least known enough to stop myself before blindly walking into trouble.

I agree with your caution on salvaged parts. After this weekend, I am willing to pay extra $$$ to get something that I can install without having to do my own quality checks.
 

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Here is a pic showing gap I was talking about between camshaft cap and cylinder head. (Pic taken from ebay listing provided by @McRider ). I now assume that this gap needs to be there?


View attachment 18167

@McRider

Can confirm motorcycle salvage parts are hard to find. Called around a bunch of places about one day's drive from where I live and couldn't find anything.

I did find some crashed bikes on auction a few days drive away, but I think that will be way more trouble than it is worth for me.

Thanks for sharing the Ebay listing, but it looks like N400 part number (OEM part 11008-0886 for '18, '19, and '20 N400) doesn't match Z400 part number (11008-0967). So maybe some minor differences between the engines?

I didn't have any luck searching for Z400 engine cylinder head on Ebay.

@Muchacho22

Snapped at the threads.

BTW, your plugs look great!
That gap in the pic is before it is bolted down. Gap tolerances are found in sec 5-20 in the manual. Literally the width of a baby's hair. Just enough for oil to flow between the metal parts.
 

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Here is a pic showing gap I was talking about between camshaft cap and cylinder head. (Pic taken from ebay listing provided by @McRider ). I now assume that this gap needs to be there?


View attachment 18167

@McRider

Can confirm motorcycle salvage parts are hard to find. Called around a bunch of places about one day's drive from where I live and couldn't find anything.

I did find some crashed bikes on auction a few days drive away, but I think that will be way more trouble than it is worth for me.

Thanks for sharing the Ebay listing, but it looks like N400 part number (OEM part 11008-0886 for '18, '19, and '20 N400) doesn't match Z400 part number (11008-0967). So maybe some minor differences between the engines?

I didn't have any luck searching for Z400 engine cylinder head on Ebay.

@Muchacho22

Snapped at the threads.

BTW, your plugs look great!
Thanks. Hoping I just did it right as it was my first time. Turned on with no issue and a small 1km trip to the gas station round and back eveything seems to be fine I just hope it wont break on me.
Unfortunately, though, I will probably not be around to enjoy them as I decided I am selling the bike. Hence hoping eveything turns out to be okay and the engine doesn't blow up on the new owner :oops:
 

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Discussion Starter · #16 ·
That gap in the pic is before it is bolted down. Gap tolerances are found in sec 5-20 in the manual. Literally the width of a baby's hair. Just enough for oil to flow between the metal parts.
Now I am even more confused as to why the camshaft part did not seat and cracked. I installed the cam cap and upper chain guide together, and started hand tightening the bolts in the sequence shown on 5-20. upper chain guide seated no problem. I'll dig in there tonight and see if I find anything misaligned or out of place.
 

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Discussion Starter · #17 ·
Thanks. Hoping I just did it right as it was my first time. Turned on with no issue and a small 1km trip to the gas station round and back eveything seems to be fine I just hope it wont break on me.
Unfortunately, though, I will probably not be around to enjoy them as I decided I am selling the bike. Hence hoping eveything turns out to be okay and the engine doesn't blow up on the new owner :oops:
If it starts up and runs fine, then I'm sure you did everything correctly! I would think that a problem with the cams/engine timing would be obvious almost immediately!
 

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That gap looks big -- if it takes more than a few inch pounds on the cap bolts (gently, in order) to eliminate it, I would not go further -- all you should have to do is compress a few valve springs.
 

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Now I am even more confused as to why the camshaft part did not seat and cracked. I installed the cam cap and upper chain guide together, and started hand tightening the bolts in the sequence shown on 5-20. upper chain guide seated no problem. I'll dig in there tonight and see if I find anything misaligned or out of place.
Are you 100% sure you assembled everything correctly going by the manual? The other folly is that the crankshaft was not lined up to the straight line position, and your cam sprockets was not aligned. Do you have a pic of the damages?
 
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