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Discussion Starter · #1 ·
I bought a 2011 Grizzly 450 on the cheap knowing it would probably need engine work. It had been sitting a while so I put a new carb on it and cleaned the rest of the fuel system, changed the oil and filter, checked compression, checked the coolant and cooling fan operation, all looked good and I was able to get it running to hear it and do any further diagnosis of potential issues. As soon as I got it running I could hear a definite, loud ticking. I'm thinking it could be a connecting rod bearing because the top end looks good and compression is good, but want to get some opinions here. I couldn't attach the video so you can check it out at the link here, you can hear the noise pretty clearly: IMG_5109.MOV

When I drained the oil I didn't find any evidence of internal damage, oil was dirty but not metallic and no chunks, etc. I'm trying to think of anything else it could be but can't come up with any other ideas, valves maybe?. I am also wondering if it's possible to get an inspection camera into the crank case to verify an issue with the crank or connecting rod before I pull the engine? Thank you for any input!
 

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Discussion Starter · #3 ·
Hard to tell from the video the source of the noise but it sounds like really sloppy valves to me. Have you check your intake/exhaust clearances yet? Tappet style valves super quick and easy to adjust.
Thanks for the input! I haven’t checked the valves but I’ll definitely give that a try first and post back here with an update
 

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Discussion Starter · #4 · (Edited)
Update: I checked the valves, they were definitely way out of spec, intake and exhaust both were 0.03mm, I adjusted intake to 0.065 and exhaust to 0.17. Unfortunately it didn't have any effect on the noise. I also found some metallic power and a few chunks inside the valve cover on the exhaust side, so that's not a good sign. It looks like at least a top end rebuild is in order? Is there a good source online for engine parts?

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Update: I checked the valves, they were definitely way out of spec, intake and exhaust both were 0.03mm, I adjusted intake to 0.065 and exhaust to 0.17. Unfortunately it didn't have any effect on the noise. I also found some metallic power and a few chunks inside the valve cover on the exhaust side, so that's not a good sign. It looks like at least a top end rebuild is in order? Is there a good source online for engine parts?

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Sounds like a rod knock to me, I did hear valves in there too before.
a rod will change with load, valves won't. I bet you have a bad rod bearing.
 

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Discussion Starter · #7 ·
thanks for the input, I think you’re right on the connecting rod, and I learned how to adjust valves 😁. I got started taking the motor apart, got the top end off, in the attached pictures you can see how bad the piston and bottom end of the cylinder are. I can’t catch my fingernail in the cylinder marks but the piston is really bad. I got a short video of the play in the connecting rod. I’m guessing it is more than what should be there and that would explain why it looks like the piston was getting knocked around in there? Here’s the video of the rod: Video Jan 26 2023, 7 51 13 PM.mov
 

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