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


6 replies to this topic
  • Youngrider82

Posted May 31, 2009 - 03:10 PM

#1

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

  • KJ790

Posted May 31, 2009 - 04:19 PM

#2

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.

  • CaptainKnobby

Posted May 31, 2009 - 04:52 PM

#3

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.

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  • Ogener

Posted May 31, 2009 - 04:52 PM

#4

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

  • alex211

Posted May 31, 2009 - 05:07 PM

#5

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.

  • KJ790

Posted May 31, 2009 - 05:16 PM

#6

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.

  • usmcpaul

Posted May 31, 2009 - 05:26 PM

#7

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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