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Bog Issue / Top End Hours

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I have a 2008 YZ250 and actually have 2 questions.

1) How many hours do u guys put on your top end before changing it. Mine has about 15hrs (all practice with one race). I am a top 10 B rider and only ride track.

2) I have a bog issue that only accrues when i roll on the throttle from nothing to fully tapped. If i go nothing to half it dosent bog at all. If i go no throttle straight to WOT there is no bog at all (not a gradual roll). I noticed today that it also boged when i was out for the first lap right after they prepped the track coming out of a wide sweeper turn that leads right into a uphill the bike boged for a quick second then took off. I though it was carb issues maybe something was effecting the switch from pilot to main jet so i took it apart and cleaned it out. Didnt find much inside the carb there was a little bit of gunk in the pilot jet. After the carb clean i put the bike back together and test road it out in the pasture and it is still bogging.

When the bike does bog if i hold it at wto and dont let off the thing will bog for days it dosent stop. There was only one time when it revived itself from a bog. If i pull in the clutch and try and make it bog by rolling on the throttle it wont do it. I found that after it bogs if i stop and rev the bike letting it hit the limiter a couple times i can go for a couple corners before it bogs again.

My bike is ported and polished has a pro circuit works pipe and a shorty silencer. I replaced the top end 15 hours ago. Mix my gas 50:1 and i am running the right jets for the altitude in co using the 1% per 1000FT rule. The bike has always ran fine and i has never had the siltiest hesitation. This just started happening.

any help or ideas would be appreciated!

Thanks

tyler

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Air filter clean? I'm sure it is but had to toss that out. Dude, you may have just got a bad can of gas. If its been running fine and this is the first time its freaked out then I think about the fuel you got before this all came up. As far as the time on a top end, your going to get all kinds of time line post on that. Some top ends last what seems forever and some just don't seem like they last 10 hours. All it takes is one time, sucking dirt pass the air filter or loose air boot. When you ride the same bike for so long, you get an ideal on how the parts wear is on that bike. If it runs tight with no topend noise, then run a comp test, its on the low side, change it, if it still on the high side, leave it in there.

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I thought it could be gas as well. I drained the tank and ran brand new gas today. 4 gallons of 91 and 1 gallon of 101.

How do u check crank seals?

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