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Discussion Starter #1
A while back my 700 sat unused for 6 months or so and when I drove it before parking it everything was fine. When I went to drive it again there was a brutal knocking noise that sounds like it's coming from the bottom end. Removed the clutch and noise stayed the same so it's in the engine. Knocking noise increases/decreases with RPM's.

Fresh oil, plug, gas and air filter changed nothing. Disconnected Dyna ignition, no change.

All tests on the pod seem okay.

Adjusted timing (my first time, think I did it right?) and no change. Cam chain is tight.

Did compression test today 3x and each time the strokes increased pressure evenly before settling on 90 PSI. According to the manual this is quite high?



Back when this first happened I drove it down the road to see if it just needed to be warmed/loosened up. Lacking power, irregular idle, and top speed of 70 kph at full throttle. Back off to 3/4 throttle and I could get up to 80 kph. This doesn't make sense to me.



What do I do?
 

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Discussion Starter #2
Did some reading online today and watched a few videos. Sound is the same as videos on Youtube with guys asking if it's rod knock or piston slap.

I tried testing for rod knock using a screw driver to sharply push the piston down on the downward side of the compression stroke and couldn't hear any knock. The piston just pushed down without making any noise.


It sounds to me like the noise is coming from the bottom end, but could it be piston slap? I assumed if it were slap that the compression would be lower.
 

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Grizzled
2014 Yamaha Grizzly 700 EPS
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Hopefully someone can come along who can help out. Just seems unrealistic that your quad was fine, then parked for a bit and now has a bottom end engine issue??? You sure no one took it out and ran it without your knowledge?
 

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Discussion Starter #4
Hopefully someone can come along who can help out. Just seems unrealistic that your quad was fine, then parked for a bit and now has a bottom end engine issue??? You sure no one took it out and ran it without your knowledge?
110% sure nobody rode it. Simply not possible.


I'm completely stumped on this one. Like I said, totally fine and ripping wheelies before I parked it and now it sounds horrible with that very odd 3/4-full throttle thing as described in the first post.
 

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CUT OPEN THE OIL FILTER AND LOOK FOR ANY METAL PARTICLES. IF YES TAKE A MAGNET TO THE CUTTINGS, IF THEY STICK TO MAGNET THEY ARE BEARING FILINGS CUTTINGS. IF THEY DONT STICK TO MAGNET THEY ARE ALUMINUM AND WOULD BE COMING FROM THE PISTON. CHANES OF PISTON DAMGAE AND STILL HAVING GOOD COMPRESSION ARE VERY SLIM THOUGH.
I LOST BIG END OF CON ROD WITH LOW OIL LEVEL BEFORE. UNIT WAS DOWN 1 LITRE OF THE 2.9 LITRES IT HOLDS
 

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You might be able to isolate the noise with a long screwdriver or piece of hose, put handle in ear & tip on motor while running, go from barrel to crankcase & back again a few times to see where the noise is loudest, close eyes to concentrate better, move all around to bracket the noise.
 
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