So I have been having this issue and I am at a loss as to whether I can actually fix it or not. I'll start from the beginning.
On September 17th, I started my bike at work and headed home. When I got to an intersection, I noticed a loud clacking/knocking sound coming from my bike over my earplugs. When I got home, I took out my plugs and it was incredibly loud. So I stopped riding it.
I dropped and checked the oil - it was still within the sights and not low, and there was no noticeable metal in the oil. I attempted to check the valves, but I honestly couldn't figure out exactly how to get the feeler gauges in to read (And I couldn't get the timing cover off either) so I took it to a shop to have them adjust it. I want to note that while driving it to the shop, I noticed absolutely no change in power or response - it's just loud. The biggest thing I could see was that at least it was oily so the head was seemingly getting properly lubed. He said the exhaust valves were tight, intake were loose, he "set decompression lever cable freeplay", replaced the tappet cover o-rings, and "checked that the flywheel rotor is tight".
The sound is still happening, so I got a stethoscope and tried to listen to where the sound was coming from. I might be misunderstanding this, but I could hear the sound all the way up the cylinder. It was noticeably louder towards the bottom. When I had it in front of the starter motor, it seemed to be absolutely the loudest. But, at the same time the sound was clearer towards the top of the cylinder on the right hand side of the bike.
Here is a video of the sound, although since it was taken on my phone it is a little difficult to hear. https://youtu.be/a3AB8_z7too
The mechanic I had taken it to said "motor sounds like bottom end rod or crank bearing," and that it would be cheaper to just replace the engine. I am not positive that he is right though and any opinions would be amazingly well appreciated. I want to try my best to fix this.

I forgot to mention that, thank you. It is a 2011, a little over 15,250 miles. I swapped the cam chain adjuster for a verslavy at around 12,000 miles. So it seems unlikely it is the adjuster. I also run Rotella T6 in it, changing oil between 2-3,000 miles with the filter being swapped every other time.

Steph wrote on 09/28/17 at 13:30:22:

Yes, I agree, any work you have a mechanic do to fix this, it will be cheaper to replace the engine.
He can not check the flywheel nut without removing the stator cover, rotor and starter clutch.
The bottom end on these things is nearly bullet proof.

I did buy a bike with a similar noise and found a burnt piston.
So my guess is it's piston related, either burnt piston or piston slap.

My brother said about the same thing about it as your mech.

You might be able to see a burnt piston by looking at it thru the sparkplug hole with a borescope.

Steph wrote on 09/28/17 at 16:32:41:

It might not look like anything or there'll be a piece of the piston missing.

A bore job and a new piston

I do have a Clymer's manual, the pictures can just be a little vague sometimes.
I'll start tomorrow with a compression test and go forward from there. Although since it hasn't lost any power, I'm assuming that won't tell me very much. I'll also order a cheap little endoscope to check out my piston to the best I can.
So I suppose I have 3 main questions then. Am I able to do this kind of work with the engine in the frame? If not, do I need to drain the oil to remove it from the frame? And where might I buy a new piston? I'm having trouble finding any online to get a rough estimate on price of that is indeed the problem.
Thank you guys so much, this is a helpful starting point and I think I'm a little more confident moving forward.

My engine developed a horrible clank - it started as a tick when the bike had 400 miles on it and it became horrible by 1,000 miles on it.   It was worse at idle, as the rpm increased it smoothed out.  When idling around town folks a 1/4 block away would look to see what the horrible racket was.

It turned out to be a loose flywheel nut.....and would have been a relatively cheap and easy fix if I had known what to check.  The flywheel nut is behind the rotor.......and it requires pulling the rotor and starter gear, and a deep 46mm socket to check it.  I suspect your mechanic at the dealer only checked the bolt on the end of the crankshaft that can be checked by removing the threaded timing inspection cover - checking the flywheel nut requires removing the left engine side cover, removing the rotor (puller required), removing the starter gear, and then checking the tightness of the flywheel nut (46mm deep socket, torque wrench and flywheel holder required).

Before you take the engine out of the frame.....I would really suggest you get this nut checked properly.  The noise if very much like you describe, it is evasive to pinpoint as the noise is dissipated through the crankshaft, into the bearings, then into the engine case.....it rattles in a way that cannot be isolated by listening outside the engine.

I will run the compression test and look inside the cylinder when the camera comes in, either Monday or Tuesday. Looking at Clymers, it says that compression should be between 145-203psi, so is that how you knew you were in trouble?
I remember reading your flywheel issue before and you're right, it could be that I suppose. Considering the rarity, it would be just my luck that it happened to me too. Don't you need a special tool to remove the rotor and starter gear? Where would I get such a tool and what would it be called? And how deep of a socket are you talking? That also leads back to the issue I was having where I could not remove the timing cover. Maybe I should just buy a cheap crowbar that fits the slot, I don't know.

Dave wrote on 09/29/17 at 13:53:53:


What would you think shipping would run to AZ then, if you don't mind guessing?