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Total hour before rebuild or bow up on 14-18 bikes?

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Hey guys,i want some fact about how many hour did you do before you rebuilding your yz250f 14-18 or you blow up,thanks

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Modern 4-strokes don't just "blow up."  ?

Without any details of how you ride and what kind of riding you do, your question is entirely pointless.  You may as well have asked how often to change bodywork?

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If you are a a rider that hits the rev limiter a ton, you need to get a new connecting rod if you have a 15 ASAP. Also fast riders should be doing top ends 20-40 hours. Weekend Warriors or C level riders I'd say top end 40-60 hours to be safe but I've seen these bikes go 70+ hours without even having the valves checked. I wouldn't recommend that. Just go by what the manual says and you will be fine.

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I realize there is quite a difference in the motors but I have a WR250f motor that prob has couple of hundred hours on the original piston and no plans to change it anytime soon.  4- strokes don't just blow up for no reason.

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Top ends and a timing chain are cheap. Why risk it?

 

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I have a 2014 so i remplaced the rod and the top end at 60 hours and now i’m 100 hours.so i will do a top end now before the summer.and I don’t know when i will have to change the valve ?

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I am a A ish rider and am hard on bikes. I usually put about a 150 per year and then sell the bike every year. I replace pistons at 20-25 hours. I have cracked the top of the piston between the valve cutouts a few times and the manuals say to replace around 12 hours. I have had the bike "blow up" a few times. Its a whole lot cheaper to replace more often then necessary then to have one "blow up." Also a whole lot faster. Anyone need cylinders or heads for 2018 yz250F's. I have a few oem ones that have been re-plated (cylinders) and new valve seats installed. Always do a cam chain when you do a top end.

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I did 150 hours on my 14 250F, never rebuilt. Still ran perfect. 

150 hours on my 15 FX, will do top end a cam chain soonish. 

Fast B/slow A woods rider, not particularly hard on bikes. 

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206hrs on a WR 2106my used for woods and cross country

Was burning a bit of oil but otherwise fine

Piston still measured in tol as did cylinder20181201_155242.jpg.48d4c072958e946ebdb50abbf3142074.jpg

 

 

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10 hours ago, Vintage Not Pimpage said:

I did 150 hours on my 14 250F, never rebuilt. Still ran perfect. 

150 hours on my 15 FX, will do top end a cam chain soonish. 

Fast B/slow A woods rider, not particularly hard on bikes. 

Thanks for this.  After reading previous posts I was stressing a bit.  I bought my bike from an A level rider and it has 40 hrs total on it.  The big bore kit apparently was put in at 10 hrs.  

I will be extraordinary easy on the engine because the riding we do is all slow, technical so I suspect the current piston will last a long time yet.

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When you guys are saying "rebuilt the top end" what are you meaning exactly?   For reference I have a 2015 WR250F. 

thanks

 

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bought a 2015 YZ250F that had blown up at 89 hours becuase the Conrod hadn't been changed. it went straight through the cylinder

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