[jedaks]

Hello all, I'm hoping I can get some help with a diagnosis. I'm hoping it is just a simple pushrod adjustment but...
My bike is a 2004 kick only 535. Runs great. No leaks. Rebuilt a couple of years ago with Ace's help.
As I pulled into my driveway this afternoon I heard a loud metallic rattle/clack that was in sync with the rpm. There was also a small oil weep from around the spark plug. I let it idle and listened to the noise which seemed to be loudest from the right side of the engine, up the top end. The engine was warm from the ride home (which it behaved perfectly). The bike idled about a minute then died. I restarted it a moment later and it fired to life, but it died a few seconds later. Rattle kept pace with the RPM as I gently rolled the throttle. There was no smoke from the exhaust.
I noticed the oil weep around the sparkplug. I pulled it and it is filthy sooty,but not wet. I haven't changed my jetting or timing or anything like that.
My pushrods had a very slight up/down wiggle but they were not excessively loose. The inlet was moveable with finger pressure and the exhaust spun quite easily.
I had other chores to attend to and didnt' have time or daylight to check it out further. I'm hoping that a pushrod adjustment will fix the problem but I somehow don't think they are the culprits.

What else can I check? Rockers? Valves? Broken oil ring? The piston is an Accralite inside an alloy Hitchcock's barrel, with about 13,000 klm worth of use.

Thanks
I

[Mr.Mazza]

I would start simple, take out the plug and peer inside, maybe some oil in the chamber? Change the plug too.
Besides that dunno, broken rocker?

[ace.cafe]

If it isn't pushrod adjustment, then you need to remove the rocker covers and check out all the valve train parts for wear or breakage, and there could be a loose valve guide, or even a loose valve seat which could make that kind of noise.
Oil around the spark plug normally is coming from the rocker cover gasket, and puddling in the spark plug valley.

[jedaks]

Thanks for the tips. My systematic plan of investigation is thus:
1. Reset pushrods and start her up, listening closely. If no noise, go for a ride near home (in case I have to walk!) to get the engine warm and keep listening. If no noise then I'll call it good and just keep an eye/ear out.

2. If noise persists, then remove tank and rocker covers and have a look. Roll the engine with the kicker. If nothing obvious, start it and have a look/listen.

In case of a loose valve guide or valve seat...what would I looking or checking for? A broken valve spring would be obvious enough I suppose.

Many thanks

[jedaks]

Hello again,
a pushrod adjustment didn't do much. The bike started but weakly and died a few seconds later, and I could her that clack clack clack. So by rolling the engine with the kicker and listening I noticed that when the exhaust pushrod moved, the clacking noise occured.

So I removed the exhaust rocker cover and rolled the engine again. The noise seemed to occur when the exhaust valve moved. I removed the rockers and took them apart and noticed a few flakes of silver/white metal inside. See the attached photo.
I have an Alpha roller bearing in the crank with a steel conrod, not a floating bush big end. So where could this have come from?

[Bulletbaz]

Have you checked to see if the flake is magnetic or not? I say this because when I stripped my engine once, I had a bit of metal just like that in my rocker and it turned out to be a small flake from the (presumably case-hardened?) camshaft lobe that had started to break up. Discovered it just in time!

[jedaks]

Don't seem to be magnetic. I've got the rockers off now. When I roll the motor I can still hear the click clack. My guess is a valve loose and touching piston or piston is slapping barrel.

[ace.cafe]

If you hear the noise when the rockers are off, then the valves are not involved.
It's something in the cylinder or the bottom end area.

[High On Octane]

If you hear the noise when the rockers are off, then the valves are not involved.
It's something in the cylinder or the bottom end area.

+1

[jedaks]

Found the problem

My gudgeon pin clip has broken and the gudgeon pin had shifted through the little end. That was the noise.

[High On Octane]

Did the pin damage the cylinder wall?

[ace.cafe]

That is not a normal occurrence.
Something else happened, which caused that to happen.

Judging by the burn marks on the piston, I would guess gross piston distortion from overheating. That piston even shows burn marks inside the pin bore. I have never even seen that before.

[High On Octane]

That is not a normal occurrence.
Something else happened, which caused that to happen.

Judging by the burn marks on the piston, I would guess gross piston distortion from overheating. That piston even shows burn marks inside the pin bore. I have never even seen that before.

Ace - Could this be the result of too tight of cylinder wall clearance for the piston?

[jedaks]

The bore is untouched. See the photo, there's not a scratch in the barrel.

Ace, there is over 13,000klm on that piston. In January this year I took the head off (10,000 klm) because I had a leaky exhaust valve. I lapped the valve back in and cleaned carbon off the piston. I put everything back together and rode another 3000 trouble free kilometers.

[ace.cafe]

Well, I'm open to hearing your technical  explanation.

There are typically two causes of popping a clip so violently that it explodes out the wall of the piston pin boss.
One would be a bent rod, or other large misalignment.
The other would be distortion from overheating.

Normally, those pins don't see sufficient side force to blow out these clips, which is why you don't see this often. Some kind of geometry problem is usually the underlying cause.