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Discussion Starter #1 (Edited)
I'm Nick, from Sydney, Australia. I've owned this red CX for around six months now, and have put around 5,000km on it, for a total of around 62,500km. I'd always intended to make it into a bit of a project, but it's been my only transport, so time to get it of the road has been limited.

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Pictured here, in happier times with my friends Ninja 650

The other night, the bike forced my hand. It had been down on top end power, which I assumed to be a carb issue. As I was planning to take it down the coast, I decided to check over everything else, and while I was looking it over, do an oil, filter and spark plug change. The valve gaps were right on spec, and the oil change went smoothly, but over the next day it lost power dramatically, culminating in a big clunk in the middle of a busy intersection. With the starter just making a click noise, and the bike not turning over at all when I attempted to hillstart, I sent my girlfriend to catch a train home, parked it somewhere safe and collected it with a trailer last night. My theories at this stage were cam chain related, but the way the motor locked up on me did seem odd.

I'm pretty new to this sort of work, and this is my first foray into pulling one of these apart. If anyone spots me doing something silly or unsafe, please don't hesitate to point it out! That said, on with the teardown:

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I don't have any photos pre heads off, but the process was pretty straightforward. I used a combination of my Haynes manual and a Honda service manual thoughtfully included by the previous owner, and the only issues I had were with removing the right hand rocker assembly (I may need to look at getting replacements for the small dowels that secure the rocker) and the removal of the heads themselves, especially the right hand one, which I suspect has something to do with the suspicious lack of oil on the lower right hand stud (the same location I had difficulty with when removing the rocker assembly). Regardless, some liberal application of a rubber mallet later, and both heads popped free nicely.

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The inside of the cylinder looked to have significant carbon buildup, along with some corrosion on the piston, however the cylinder walls look smooth and clean aside from a thin ring of carbon around the top which is nice.

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Valves look similarly carbonized and corroded.

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Last thing I did today was drop the engine out of the frame for further teardown to continue at a later date. As I was draining the oil, I noticed some tiny little metal shavings in the pan. A couple of them looked like brass, which has me worried about my bearings. I'd like to fix this motor rather than buying another one if I can avoid it, but if it's toast it's toast.

As of tomorrow I'm heading to Melbourne for a holiday with the girlfriend, sadly in her car rather than on the bike. I'm back on the 28th of this month, so expect more updates then!
 

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If the material in your filter is brassy it's likely a failed big end bearing. Make sure the metal in the oil is actually a coppery or brassy colour and it's not the oil making silvery flecks look coppery.

It does look like the cylinder may have been contacting the head near the exhaust valves. If so, this would be another indicator of a failed big end.

If you crank the motor over until that piston passes TDC and push down on the piston with a hammer handle does the piston move down? {without moving the crank}
 

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Discussion Starter #4
Well I'm back from the dead, or at least Victoria. This may be a slow thread the way things are going right now, as I am pretty time poor. That said, I've gotten myself some wheels so I can at least go buy parts.

Anyway, I got the flywheel off and the first thing to become apparent is this:
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The cam chain had a good old munch on the block there. Here's an image of the underside of the tensioner retaining plate. Made it tricky to get that bolt out!
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So with the cam chain off, the cam spins freely (at which point I realised I hadn't taken of the fan yet. Whoops!) but the motor still won't turn over from either end. As far as I can tell, my next step will be to pull the clutch and the front cover so I can get a look at the crank. Correct me if I'm wrong there, the haynes manual is pretty vague regarding that part of the teardown. Regardless I was working in the 40 degree (celsius) heat today and so that was all I was willing to do! Hopefully will have more updates soon.
 

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