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YZF valve life

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I have an 03' YZ250F and was wondering how often I should check the clearances. Do I wait for it to start making noise or go ahead and check it out? How many hours should I expect out of the stock valves riding it fairly hard?

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i also have an 03 yz250f and i try to check my valve clearances every 5 to 10 rides. as for how long the valves will last im not sure but after changing my top end recently my valves were holding up just fine

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The valves won't make too much noise if they need adjusting. Most of the time when the valves get out of spec you can tell by sudden hard starting, or maybe a loss of compression. The valves themselves hold up pretty well. They are all titanium, and in a pattern of five, instead of the usual four in motocross engines. The five-valve theory is that with five, smaller and lighter titanium valves they don't beat against the seats as hard and require less adjusting. If you bang it off the limiter commonly, then you should expect to get less life out of the entire valvetrain.

I have never had to adjust the valves in my '04 250F, and I ride it pretty hard.

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The valve life on our 03 was 400 hours. At 400 hours they started tighten up every couple rides. I replaced them with another set of OEM valves, so we should be good for another 400 hours.

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yah, when you start to smell burning oil its a sign of dried up valve stem seals and you will need to replace those. To do a top end is fairly easy on the yamaha, but you have to make sure your bike is completely dirt and dust free. PM if you want to see wut i used for my "valvespring compressor".

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The five-valve theory is that with five, smaller and lighter titanium valves they don't beat against the seats as hard and require less adjusting.
The idea that the 5 valve set up is a major reason for the superior valve life in YZF's has been around for quite a while, but it's not the reason they last longer. You'll note that the YZF has the same number of exhaust valves, and they last much longer, too. The simple truth is that Yamaha makes better valves than the others do, uses a more durable coating, and matches their seat materials to the valves better. They're a higher quality machine, and that's all the more complicated it is.

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Prices on the valve train go with what gray explained. Look at the prices for oem valves for the Honda,much lower prices. Keeping them coming back for more. I know this sounds like a Honda slam,but this is not my intention. The head for the 250F is considerbly more than the Honda also. This is a example,YOU GET WHAT YOU PAY FOR!

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The head for the 250F is considerbly more than the Honda also.
Part of that is due to the fact that there is a good bit more work involved in the YZF head than the Honda. The cam tower unbolts off of the CRF head, which leaves 4 valve seats and guides and a machined surface on both sides. The YZF head includes the split cam bore and lifter bores as well.

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Thanks guys! I'll probably wait a little later then, because it starts easy, runs fine, and doesn't make a lot of noise. I guess just talked to the Honda guys a little too much :thumbsup:

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