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Engine noise diagnosis help

mikerophone

mikerophone

Forum Mentor
Past Site Supporter
Got the engine back in my 850 finally. While I had it out I sandblasted it and painted it and replaced all of the engine case cover gaskets change the oil and filter and replaced a few shims...that's all that has changed.

I'm leaning towards a valve noise and my mechanics stethoscope seems to verify this but while I'm waiting for the head to cool down to measure my clearances again, has anyone heard this before?

[video]http://flic.kr/p/wyiZr5[/video

Looks like my Flickr video may not be working I'm uploading to YouTube now.

Ok, here's the
 
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The noise cycles in and out with about the frequency that a valve shim rotates. My guess is that you have a shim that isn't dead flat or isn't sitting square in the bucket. The noise might not actually be from tappet clearance but from cam end play which knocks when the shim is one direction and not when it's in another. I've heard the same sound in car engines when a tappet is worn crooked.
 
Thanks fo the reply John - I hope it's something that simple and it should be, nothing else changed. They'll be cool enough by tomorrow when I get off work to take a look under the valve cover. Hopefully the cam lobe isnt worn...
 
If i hadn't read that the stethoscope points to a top end noise i would have guessed at a clutch rattle requiring a carb synch.
 
Thanks Steve, the clutch area was untouched other than that the shift fork wiggled loose while I was replacing covers so I had to slide it back in to place. It definitely needs a carb sync after the shims were replaced but it's not terribly far off considering.

More info tonight when I get off work and take a look. I'll possibly pull the clutch cover and take a look in there as well as I know I have enough oil in there, but still none showing in the sight glass. I did tape and mask off the area when painting but was pretty sure I got it all out.

One other tidbit I should share is that I bought an 82 850L that sat for 23 years to put the 12k engine in my 50k 81 850G frame and after cleaning the carbs and gas tank I rode it down the road and back (tires were so dry rotted so I don't even get into 4th gear) and started switching motors. It sat for a few months while other projects took precedence but then I bead blasted, painted and put it there.

One other thing is I did notice a bit of smoke when I first started it but I had poured some oil in the cylinders and in the bucket valleys so I could hand crank the motor while checking shims and line up the bolt holes on the driveshaft so I didn't worry too much about it. There was no odd noise before but I am definitely leaning towards the shim in the bucket not being square. The noise is barely noticeable at higher RPM's but I didn't want to run it long, I suppose it could have settled in if I had but it also could have floated out and I don't want that!
 
Someone recently posted a video with the exact same noise on his 650 engine. I suggested it could be the cam chain. Did you have the tensioner off at any point?
 
Solved! It was valve clatter.

Solved! It was valve clatter.

Thanks Charles - I did, to replace the gaskets.

Turns out it was the valves as suspected. Luckily the shims were all flat however upon checking clearances, I had mixed some shims up while putting them in! In my defense I did have my daughter helping me on my iPad enter the numbers into Steve's spreadsheet when I measured them before ordering my shims from Ray and the shim club. Some of my intakes need to be swapped with the corresponding exhausts and once I switched those around viola!

 
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