2019 YZ450F Piston knock at 50Hours

wst260
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wst260
Hey all,

I’ve had my 2019 450 for about 8 months now and it’s just hit 50 hours, went to go ride it last weekend and just before i pulled onto the track the piston started knocking louder than the actual bike just idling… Bit lost for words as i’ve babied this bike.. I’ve heard of cam chains on this model letting go around 50 hours but has anyone else had a piston knock this early?

Only asking in comparison to my 2019 YZ250F, has 105 hours and has had the piston replaced once in its life span and used to be an ex-race team bike and still goes on like a trooper. I’m a front of the pack B rider for reference if it helps anything.


Cheers
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murph783
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murph783 1/4/2022 6:54am
1/4/2022 6:54am
Yeah, definitely check that chain out. Or honestly just replace it, they’re cheap.
willbilly
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willbilly 1/5/2022 5:04pm
1/5/2022 5:04pm
The YZ 450 has a reputation for being very durable. Sure, yours might be the exception but you won’t be able to to tell without a leak down test or disassembling the top end. Good luck and please let us know what you find.
wst260
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wst260 1/6/2022 12:01am
1/6/2022 12:01am
willbilly wrote:
The YZ 450 has a reputation for being very durable. Sure, yours might be the exception but you won’t be able to to tell without a...
The YZ 450 has a reputation for being very durable. Sure, yours might be the exception but you won’t be able to to tell without a leak down test or disassembling the top end. Good luck and please let us know what you find.
Update: Camchain skipped 4 teeth, piston way past it’s prime and damaged. Thankfully i turned it straight off and no damage to any of the other internals. My Personal Mechanic said to be changing the camchain every 20-30 hours and top end every 40-50. Didn’t expect such low numbers from a YZ450 (The volvo of MX bikes) but it is what it is i guess 🤷🏼‍♂️
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willbilly
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willbilly 1/6/2022 5:05pm
1/6/2022 5:05pm
It’s a miracle the valves weren’t bent. Bottom end too. I’d say your mechanics schedule is way conservative. Cam chain probably didn’t fail, most likely tensioner. Go to manual cam chain tensioner and you will never have that problem again.

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