How often will I have to replace valves in YZ 450?

I was wondering how often I would have to either replace valves or piston ect....

As long as you change the air filter and oil often, the valves should last you a long long time. You should be able to get a couple years of riding out of the valves depending on how much you ride. You should still check the valve clearance regularly to be safe though. Pistons last a pretty long time as well, but you should change them about once a year depending on how much you ride. I change my piston every 50-60 hours on my hour meter, and it costs me $150 for all the parts needed.

As long as you change the air filter and oil often, the valves should last you a long long time. You should be able to get a couple years of riding out of the valves depending on how much you ride. You should still check the valve clearance regularly to be safe though. Pistons last a pretty long time as well, but you should change them about once a year depending on how much you ride. I change my piston every 50-60 hours on my hour meter, and it costs me $150 for all the parts needed.

I was wondering if you put new rings in before then or do you just do both at 50-60 hours?

I done my first topend at 50 hrs exactly. I measured the piston according to the service manual and it hadnt wore a bit.

I have about 24 hours to go till I hit 100hrs and then I will tear it down and measure the valves this time.

I would go do a search in the YZ 400/426/450 part of the forum but I have heard of yz 450s reaching 200 hours without a single valve adjustment. Talk to Grayracer in that section of the forum, he is very knowledgeable on the yamaha 450's

As long as you change the air filter and oil often, the valves should last you a long long time. You should be able to get a couple years of riding out of the valves depending on how much you ride. You should still check the valve clearance regularly to be safe though. Pistons last a pretty long time as well, but you should change them about once a year depending on how much you ride. I change my piston every 50-60 hours on my hour meter, and it costs me $150 for all the parts needed.

You're the man KJ790, I agree with everything you said.

I was wondering if you put new rings in before then or do you just do both at 50-60 hours?

I done my first topend at 50 hrs exactly. I measured the piston according to the service manual and it hadnt wore a bit.

I have about 24 hours to go till I hit 100hrs and then I will tear it down and measure the valves this time.

Personally, I won't change rings without changing the piston. To me, if the rings are worn enough to require changing, the piston has enough time on it to be changed. Though, I tend to change everything before it gets out of spec. If I'm going to take the time to take the engine apart to change the rings (and spend $60 on rings and gaskets) then I will spend the extra $70 on a piston and wrist pin to give me piece of mind. While I'm at it I change the cam chain, since these tend to be the weakest link in the Yamaha engines.

Valves need to be replaced at regular intervals. For your Yamaha that should be about 340.5 times longer than your buddies CRF. :eek:

Been there, done that.:crazy:

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