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When will my '03 YZ250F Blow Up?

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I have 60 hours on the bike since the 262 bore kit was installed. I haven't done anything to the top end at all. I do change the oil & filters regularly, and I don't run at the rev limiter too often. Is a blow up imminent at this advanced age?

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so in 60 hours you have not checked the valve lash?

shame on you!

now, had that been a red or green or yellow bike, you'd be on your 4th set of valves and have spent about 2k+ on parts.

now, go check your valve lash. adjust them if needed (ha ha ha) and think about doing a new cam chain, valve seals, piston and rings this winter.

:thumbsup:

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I like to play it safe and check the valve clearances during the off seson Winter months. Well............I check the whole bike over during those 'cabin fever' days. :thumbsup:

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When will my '03 YZ250F Blow Up?
Sunday, March 25, 2007. 20 minutes after the start of your day, which will also be 20 minutes away from your truck. I'm not seeing the actual time, must be because of different time zones. Be warned.

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60 Hrs, thats it? You should have a while to go if you keep ontop of maintenince

The point of this thread is that he hasn't kept up on the maintenance and is probably already on borrowed time. It depends on many factors but primarily how much time was on the chain/valves/keepers/ect. before the 262 kit was installed.

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Its not a 2-stroke, 60 hours is nothing. It would be a good idea to check the topend of the motor just for a little peace of mind, but you are a loooooong ways away from a topend rebuild.

Id say youve got at least 100-140 hours before you should have to worry about a rebuild. Yamaha's engines are pretty bulletproof.

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Its not a 2-stroke, 60 hours is nothing. It would be a good idea to check the topend of the motor just for a little peace of mind, but you are a loooooong ways away from a topend rebuild.

Id say youve got at least 100-140 hours before you should have to worry about a rebuild. Yamaha's engines are pretty bulletproof.

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Sunday, March 25, 2007. 20 minutes after the start of your day, which will also be 20 minutes away from your truck. I'm not seeing the actual time, must be because of different time zones. Be warned.

That is hilarious!

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Thanks for the input everyone. I get those valves checked asap then get some valve springs, guides, seals, retainers, and a cam chain ordered. Hopefully I won't have to order valves, but I guess I could do that leakdown test when the valves get adjusted.

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Sunday, March 25, 2007. 20 minutes after the start of your day, which will also be 20 minutes away from your truck. I'm not seeing the actual time, must be because of different time zones. Be warned.

LOL LOL, that is classic

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Its not a 2-stroke, 60 hours is nothing. It would be a good idea to check the topend of the motor just for a little peace of mind, but you are a loooooong ways away from a topend rebuild.

Id say youve got at least 100-140 hours before you should have to worry about a rebuild. Yamaha's engines are pretty bulletproof.

100-140 hours dosnt sound to bullet proff to me.none of these new fourstrokes seem to bulletproof.

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Compared to a 125 they are very reliable. A friend of mine has an '01 CR 125 and he replaces rings 2-3 times a year. Compare that to another friend of mine who has an '04 YZ 250F and other than oil and oil filter changes hasnt had to touch the motor yet. Im surprised he hasnt had to adjust the valves yet, but we checked the valves last winter and they were still within specs.

Granted, MX 4-strokes arent as reliable as a 4-stroke utility ATV engine, but they are a lot more reliable than any 2-stroke dirtbike engine.

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but they are a lot more reliable than any 2-stroke dirtbike engine.

i wouldn't go that far, my dad still had his 86 yz490, he bough it when it was new, we ride the hell out of it, replace the rings, when, well, not very offten. That, is a bullet proof engine.

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Compared to a 125 they are very reliable. A friend of mine has an '01 CR 125 and he replaces rings 2-3 times a year... they are a lot more reliable than any 2-stroke dirtbike engine.

I love my WR, but I could change rings on my old CR500 all season for the price of 1 valve on the WR.

Of course if I wasn't so poor I would buy a new one every season & never worry about it...

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