Suspicious engine noise. Opinions needed

[Jdcooper]

I just had my 09 Stelvio rollerized. The conversion went as advertised by a local Guzzi shop here in Ohio.  Now that it's much quieter (valve train wise) I'm hearing engine knocking which concerns me. The bike has 21K, and showed a little wear on the tappet faces when they were pulled . Symptoms go like this::

It only occurs when the engine is hot. It's quiet when cold.
Only at idle. Greater than about 2000 rpm it goes away.
No difference clutch in or out, in gear or neutral.
NO oil pressure lights or warnings at any rpm. Oil quantity right in the middle of the dipstick. Haven't changed the oil since I bought it last winter.
It's loud enough to concern me at idle, and I'm about to pull the sump unless anyone else has had this kind of experience.

I'm concerned it's a big end bearing, so I pulled an oil sample and sent it to the lab, figuring that it would peg for copper or lead if a bearing were disintegrating. No metal flakes visible in the oil and the sample came back from the lab normal. Now I'm stumped.

Anybody out there have any ideas?

[oldbike54]

 Header pipes or muffler rattling against something maybe ???

 Dusty

[Jdcooper]

I'll check.

[Jdcooper]

Doesn't seem to be an exhaust interference problem. I'll get the stethoscope out and try to localize where it's coming from.

[rocker59]

Cam Chain, maybe ?  (probably a normal noise, but you're listening for problems since your rollerisation)

[oldbike54]

Cam Chain, maybe ?  (probably a normal noise, but you're listening for problems since your rollerisation)

  :1: The engine is quieter now overall , makes other noises seem more pronounced . That doesn't mean don't investigate . No offense meant , but if you are an "herbal" American , don't partake before listening , we used to call engine noises made after partaking the "marijuana knocks"

 Dusty

[Idontwantapickle]

Are you positive it is not the usual transmission noise? It can be quite alarming when you first notice it. Does it do it in gear at a standstill? The stethoscope is a good idea.
Hunter

[MotoG5]

A big end knock will not go away and will get worse fast. In a short time you would have no doubt. Not saying its not your problem but so far it doesn't seem like it from your discerption.

[Wayne Orwig]

Been There, Done That. Got the T shirt.
My 2009 had the cams fail. I rollerized it last fall.
When hot, and only when HOT, it had a knock. It was worse at about 1800 RPM. Above that, it 'pumped up' and became quiet. The noise did NOT return at idle, until it idled for a while.

I pulled the bottom off and pulled the rod big ends. The bearings were NOT really worn. The bearing gap was perfect, as far as using PlastiGage. There was a little strip of material stuck to the crankshaft. I cleaned and measured the crank. No problem. I installed new bearings AND NEW BOLTS. Noise is gone.

Not hard to do. Parts didn't cost much. But I'm not convinced they were that bad.

What oil weight are you using BTW.

[pete roper]

I've had three, (Out of many!) engines run a big end after rollerisation. Like Wayne with new shells the clearances checked out fine. Alas they still knocked!

First up make sure that it's running the right map, the TB's are balanced correctly and the TPS is correctly calibrated. After that? If it still knocks? Inspect the big ends.

Pete

[Jdcooper]

Pete et al...

I'll check the balance, map and TPS.  If it still knocks I'll pull the oil filter and cannibalize before I get into the bottom end.  Interesting about the map: maybe it's pre-ignition  which at higher RPM's isn't an issue. Hmmmmm.....

[pete roper]

It won't be preignition. It won't be detonation either at idle. Tune or big ends are the most likely cause. Opening the filter will most likely tell you nothing though.

Pete

[atavar]

Thanks to everyone for this thread.  I learn so much on this forum.
As a side note for the more than a couple of us out here using hearing aids - If your hearing aids have a remote control most of those have a remote listening feature where the remote control acts as the microphone for the hearing aids.  This is intended for use at meetings where the speaker is at the other end of the room but  has come in handy for me a number of times where I could use it as a wireless remote stethoscope. 

[RANDM]

Thanks to everyone for this thread.  I learn so much on this forum.
As a side note for the more than a couple of us out here using hearing aids - If your hearing aids have a remote control most of those have a remote listening feature where the remote control acts as the microphone for the hearing aids.  This is intended for use at meetings where the speaker is at the other end of the room but  has come in handy for me a number of times where I could use it as a wireless remote stethoscope.

That's interesting - I'm supposed to be thinking about aids
But I'm not really keen.

Maurie.

[normzone]

Having gone nearly mad once from listening to upper end noise in the left side of my Bassa, I am now the logical one to diagnose your engine sounds.

For a plane ticket and reasonable expenses I will fly to your location, ride the bike back to my location and provide a thorough report.

[oldbike54]

 Norm , you a such a generous fellow 

 Dusty

[Wayne Orwig]

Pete et al...

I'll check the balance, map and TPS.  If it still knocks I'll pull the oil filter and cannibalize before I get into the bottom end.  Interesting about the map: maybe it's pre-ignition  which at higher RPM's isn't an issue. Hmmmmm.....

I don't think you will see anything in the filter either.
The surface of the rod bearings had hint of 'black soot' like material on them. But I really don't even think that was anything. The bearings surfaces had some 'pits' in them. That was the only thing I really found.

Below is a photo of the bearing surface. Even zooming in on it doesn't reveal anything obvious. Plastigage showed them both as tight against the crank.

[pete roper]

While they may of gauged up OK Wayne the colour and surface texture gives the game away. They are heavily contaminated with DLC, hence the queer colour.

Pete

[Chuck in Indiana]

I've never seen anything remotely like that. It's a nice even deposition, though. 

[pete roper]

Yah, very strange. I have no explanation but it is common to two, (Not my) engine failures. Whatever the *Result* I'm sure that light scarification and embeded material is the smoking gun for post rollerisation failure.

Pete