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Expected duration of bottom end

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Hey guys, wondering what an expected lifespan on the bottom end of my '13 RMZ 450 might be? I'm currently at 130 hours of C class motocross riding, pretty easy on the bike, and I change my oil often with Maxima Semi-syn. There isn't any abnormal play in the crank, according to the manual no real reason to split the cases and change the bottom end...not sure what to think? Also not sure if the crank is forged or cast from the factory? Anyone have any good solid input/data on determining when it's time for a crank?

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You are going to get a lot of wild answers on this one man. It's really personal preference. Under maintenance in the service manual. It will have a factory recommend interval to change the crank, but as far as I'm concerned as long as it's in spec for movement, it's good to go.

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Hard to say. If no abnormal noise or play it should be fine. If it were me and i had it apart id rebuild it but thats just me.

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You should be good to go... check play and listen for any abnormal noises as stated above. If you split cases, replace it. Otherwise there is no magic number for a bottom end. I just had mine rebuilt at 250hrs and it was in perfect condition when I removed it. There is no doubt "in my mind" that it would have held up longer but I was taking everything apart anyways so I figured I would replace it for peace of mind. 

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1 hour ago, BDubb106 said:

You should be good to go... check play and listen for any abnormal noises as stated above. If you split cases, replace it. Otherwise there is no magic number for a bottom end. I just had mine rebuilt at 250hrs and it was in perfect condition when I removed it. There is no doubt "in my mind" that it would have held up longer but I was taking everything apart anyways so I figured I would replace it for peace of mind. 

That's really good to hear. Everyone says "oh no way should you ever go above 150 hours no matter what the readings say" but I don't see any proof of that. I'll likely stick with checking for play until it's time to split the cases for something else, or peace of mind as you say. Appreciate the input.

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I believe there is several guys on here with 200+ hours on cranks. But like brain said just keep a eye and ear open for the obvious sounds and sights. Unless your a pro caliber rider and don't maintain the bike idk why a bottom end on a 450 couldn't last 300hrs. Change your oil every 5 hours and filter every 10. When you change the filter cut the filter open and look for bronze chips. 9-10 you'll see bronze chips in the filter before the crank goes

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17 hours ago, AdamW21 said:

I believe there is several guys on here with 200+ hours on cranks. But like brain said just keep a eye and ear open for the obvious sounds and sights. Unless your a pro caliber rider and don't maintain the bike idk why a bottom end on a 450 couldn't last 300hrs. Change your oil every 5 hours and filter every 10. When you change the filter cut the filter open and look for bronze chips. 9-10 you'll see bronze chips in the filter before the crank goes

Good idea with that, never thought about cutting the filter open. Thanks for the tip.

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Good idea with that, never thought about cutting the filter open. Thanks for the tip.


Not a problem. That's what always stops be from buying a ss reusable filter

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13 hours ago, AdamW21 said:

 


Not a problem. That's what always stops be from buying a ss reusable filter

 

I still cut them open. I put about 40 hrs on them and then pitch them. 

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On 4/5/2017 at 8:11 AM, BDubb106 said:

I still cut them open. I put about 40 hrs on them and then pitch them. 

I've been getting paper filters for 99cents, hard to beat that lol

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2 hours ago, Fade said:

I've been getting paper filters for 99cents, hard to beat that lol

Definately... If I could get them for .99c each I would switch back in a heart beat. 

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I will never ever run a mesh oil filter, they are junk *in my opinion. I was never able to get all the crap out of them. I buy a 6 pack of K&N's for like 25 bucks. Not quite 99 cents, but 4 bucks isn't terrible.

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15 hours ago, xMUDKINGx said:

I will never ever run a mesh oil filter , they are junk *in my opinion. I was never able to get all the crap out of them. I buy a 6 pack of K&N's for like 25 bucks. Not quite 99 cents, but 4 bucks isn't terrible.

Smart boy! Would never trust a mesh filter.

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On 4/6/2017 at 5:24 PM, BDubb106 said:

Definately... If I could get them for .99c each I would switch back in a heart beat. 

Gotta keep your eye out on RMATV, about once a month for a few days they go down to 99 cents!

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Gotta keep your eye out on RMATV, about once a month for a few days they go down to 99 cents!


We'll help us out and next time they go on sale post it on here !
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I've always ran mesh in my bikes with no issues. I also have a parts washer available to me at work that makes it like new every time so that helps.

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11 hours ago, Andyb756 said:

I've always ran mesh in my bikes with no issues. I also have a parts washer available to me at work that makes it like new every time so that helps.

Yep... a parts washer is super convenient. I never thought I would use one until I bought mine. Now I don't know what I would do without it. 

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Yep... a parts washer is super convenient. I never thought I would use one until I bought mine. Now I don't know what I would do without it. 

Yeah it's very handy to have.

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