Metal found in oil strainer 2014 YZ450f

I'm currently working on a 2013 YZ450F with a similar issue. A friend said he was having trouble starting his bike, specifically the kick starter seemed to be locking up. In the process of inspecting the Bike I found large chunks of metal in the oil, see attached picture. After splitting the casings, I've been unable to identify where the metal fragments have come from, although it appears as though someone was filling an oil access port between the casings and I am now wonder if the factory left FOD (Foreign Object Debris) or now Foreign Object Damage within the engine. I'm still searching for the culprit of the metal fragments and the cause of the kick starter locking up, that's another post for me.


Sorry if this isn't any help, once I find the issue I'll update my post.


Check the rod bearing. 


Another cause of the locking up could have been a skipped timing chain. Did you check that while disassembling?  Is the timing chain at all stiff at any of the links?


Explain what you mean by this statement: "it appears as though someone was filling an oil access port between the casings"


This should have been a new thread as well.

For my 2013 YZ450F the connecting rod bearing was shot, but there wasn't any other obvious faults. The timing chain links appeared fine and the chain rotated smoothly, my issue was after reassembly and the original issue remained, kick started lock up. I believe my issue is with the timing chain, definitely the timing chain tensioner, it sticks and doesn't release smoothly. Hard to believe a timing chain for a 2013 stretched so early in the engines life, strange.

I guess it's possible that the timing chain stretched once the connecting rod began failing, probably causing a torquing motion and elongating the chain, just a guess.

Maybe thumper15 isn't a top tier technician, but I am. The oil has what might be considered an abnormal amount of metal in it if it were only an engine, but it isn't. There's a transmission at work in the same oil supply along with a clutch, and both those components shed metal like an 18 year-old stripper.


It's also worthwhile noting that those chips haven't "gone through" anything.  That's the pickup strainer, so that stuff never even made it to the oil pump.  If it had, the next stop would have been the filter, before it went anywhere else.  If they're magnetic, they're likely steel from the gears.  If not, those are typicall of clutch junk.

That's also why I always service the filter with every oil change. You will find several longish, sliver-like chips of aluminum (clutch), and much smaller chips of steel (gear shed) in the filter as a normal thing. What you have to be on the alert for is a sudden increase in the size or amount of the metal in a normal oil change interval.

325 hours on mine, BTW.

Just out of interest, how often do you replace/inspect parts such as the piston and valves etc?

The frequency with which such actual inspections need to be made will vary considerably with how the bike is used.  Bikes that are ridden MX most of the time and at a high level can actually warrant a new piston every 30-40 hours, whereas my desert bike went for more than 300 on the original slug. Should have replaced it sooner, but it was OK.


The valves will usually tell you when to inspect them. Check the clearances every 10 or so.  Less often if you're comfortable with that after the first couple of checks.  If you have to actually reshim them looser twice, better have a look.  

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