2000 Ski 196 with Engine Knock?

[engineerj13]

Looking for some advice and/or info on a possible engine knock. I had my 196 with a GT40 engine out for the first time this spring to just drive around the lake as part of my dewinterization process to ensure all was in good working order. Everything was running very smoothly (@ ~4000 RPM) until all of a sudden my engine started knocking and I noticed a small loss of power (not real noticeable, 1-2 mph drop). I notice the knock at idle and higher RPM. Could this be a bearing or piston issue, or could this be a simpler issue?

I stabilize the fuel every fall using a full tank and I only use 40W VR1 oil. Oil was filled to the full mark and gas is always at least 89 octane. The engine only has 550 hrs on it.

Any thoughts or advice would be greatly appreciated...

[crobi2]

Check to be sure you haven't just developed an exhaust leak! They can sound just like an engine knock. And if enough exhaust is being sucked into your intake it can rob a little power too (usually the knock sounding ones aren't leaking that many fumes though).

You can use a 3/4 or 1" rubber tube to make a stethoscope to locate it.

Good luck