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When to rebuild/new piston/top end maintenance-2014

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So I am not a novice mechanic but certainly not an expert. Have never had to rebuild a 4 stroke toped before as my 2012 had 60 hrs on it when I sold it with valves still in spec. My 2014 is now sitting at 35 hrs and runs exactly the same as new, valves are in spec. Im just wondering when I should look at doing maintenance to keep her running good/from gernading. Im hoping to finish out the season and then work on her over the winter. Im a C rider that places in the bottom (only race maybe once a month) so hardly ever on the rev limiter and my sprockets look fairly new, etc.  Most of the time just putt around the track and jump stuff. Just curious when everyone does pistons and rings, if they replace the crankshaft/rod, etc. Anyone with a good amount of hours and still no rebuild. Whens a good time to do the bottom end, generally Ive heard around 120-200 hours. Thanks and sorry for newb question. New to major four stroke maintenance and the factory manual routine seems way over kill, new piston every 12.5 hours! Thanks again, Zach

Edited by usafwx

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You could probably get between 50 and 75 hours on a piston

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I try to do piston replacement on my son's 2014 yz250f practice bike at every 20hrs.Usually it ends up being 25-30 hrs.I just did the crank at 100hrs on the practice bike.The rod still felt tight on the crank.The crank and rod in the YZ250F is a much better set up in my opinion than the Honda crf250r crank from or previous race and practice bikes.My son is a pro rider so the bike gets road a little harder than a c rider.I think you would be good to do a top end at 40-50 hrs.

Edited by 1snotrocket

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I try to do piston replacement on my son's 2014 yz250f practice bike at every 20hrs.Usually it ends up being 25-30 hrs.I just did the crank at 100hrs on the practice bike.The rod still felt tight on the crank.The crank and rod in the YZ250F is a much better set up in my opinion than the Honda crf250r crank from or previous race and practice bikes.My son is a pro rider so the bike gets road a little harder than a c rider.I think you would be good to do a top end at 40-50 hrs.

 

What piston are you running? OEM? Undecided between OEM and Wiseco cause of the forged piston. Haven't had to do valve seats/seals yet? Thanks! 

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I use the OEM piston kit and OEM gaskets.The

OEM pistons have looked really well in the

serviced time frame I have been doing.I did try the

14.5:1 compression JE piston in the race bike but JE did not machine

enough radius on the valve relief.So I just stuck with the

OEM piston for right now.

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you could probly do next year on the same piston/rings you have in it now the biggest factore on how long parts last is by how well it has been maintained keep the oil fresh and the air filter clean and it should last for a while. i put about 120 hours on my piston and cam chain before i replaced it crank and valves looked good so i am still running original

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^ exactly.

 

Just change the oil and clean the airfilter/carb frequently and make sure valves are in spec a lot.

 

you should be able to get quite a bit of time on a piston. Just every time you're in there, check for detonation..  and all the other shit :lol:

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you could probly do next year on the same piston/rings you have in it now the biggest factore on how long parts last is by how well it has been maintained keep the oil fresh and the air filter clean and it should last for a while. i put about 120 hours on my piston and cam chain before i replaced it crank and valves looked good so i am still running original

^ exactly.

 

Just change the oil and clean the airfilter/carb frequently and make sure valves are in spec a lot.

 

you should be able to get quite a bit of time on a piston. Just every time you're in there, check for detonation..  and all the other shit :lol:

Thanks. Ya I have friends that usually wait till 100 hours, roommate looked at me funny when I mentioned doing it at 50 hours. I change filter after every ride and do the oil with filter every 3 rides with Amsoil. Valves were still in spec at 30hrs.

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