How long to top ends last in 426's


9 replies to this topic
  • srhines67

Posted July 28, 2006 - 10:50 PM

#1

What can I expect if I have the valves adjusted regularly and change the oil and air filter every ride. 400 hours. Also, when its rebuild time what $$ are you looking at?

  • jimbob69

Posted July 29, 2006 - 01:10 AM

#2

pistons and rings last years in 426's,

My 400's motor is 100% original, valves havent even needed to be adjusted since new, when I head the head off, there were still clear hone marks in the cylinder, and it isnt quite a low hour machine.


I wouldnt be too concerned about motor longevity if I were you.
Just change your oil often and keep the valves in tolerance and your suspension will need rebuilt before your topend, lol.

  • stillsun

Posted July 29, 2006 - 07:04 AM

#3

I've put probably around 200 hours alone on my YZ426F since getting it about a year ago...not sure how many hours were on it before that, but I would suspect by the two guys that owned it before me, probably around that same amount in the 4 years before I got it, so maybe 400 total.

I tore the motor down yesterday to do the big bore, the cylinder still had really good cross-hatching visibility, the ring gaps checked in a-ok, the piston had normal carbon buildup as did the head/valves....overall I was really impressed.

I would say unless it's just really exhibiting signs of burning oil or lack of compression you're good to go for at least another 400 hours.

Josh

  • tythew

Posted July 29, 2006 - 09:03 AM

#4

I have owned my 2001 since new. It has been through two seasons of hare scrambles and practice, countless trail rides, some moto and practice sessions. I don't really have a good guess on hours, but it has a lot. Just keep changing the oil, cleaning the air filter and check the valves every once in a while. Mine valve adjustment still hasn't come out of spec. I am very impressed with the durability of this bike. :thumbsup:

  • yogist

Posted July 29, 2006 - 10:09 AM

#5

I bought my 01 a year ago, have about average...10 hours a month on it...It was gently used..Almost new..Im guessin 2 TO 300, hours max on it...it looks a hell of a lot worse with me riding it, than it did when I bought it. Still runs great..Compressions good...Valves stay in spec all year long....I check them at 60 hours...I rarely get it rapped out,Lots of 2nd 3rd 4th riding, lots of technical singletrack..No mx track at all..Oil change every 10 hours...great bike...I too was wondering when I should consider doing the top end....

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  • mike_dean

Posted July 29, 2006 - 10:29 AM

#6

My '00 426 YZ, 520 hrs, 1 piston and rings (didn't need it) at 200 hrs, valves checked every 50-60 hrs, only had to shim some of the valves slightly twice, change oil every other ride, ridden mostly MX, some offroad. My friends CRF, 2 valve jobs in 3 yrs. I don't believe in titanium valves, neither does he, he installed Kibble White stainless valves last year and hasn't had to adjust yet. Mike

  • yogist

Posted July 29, 2006 - 10:32 AM

#7

My '00 426 YZ, 520 hrs, 1 piston and rings (didn't need it) at 200 hrs, valves checked every 50-60 hrs, only had to shim some of the valves slightly twice, change oil every other ride, ridden mostly MX, some offroad. My friends CRF, 2 valve jobs in 3 yrs. I don't believe in titanium valves, neither does he, he installed Kibble White stainless valves last year and hasn't had to adjust yet. Mike


Thats awesome...Thats why I bought the 426...Lurking on tt you can really see the longevity difference between manufacturers...

  • aford541

Posted July 29, 2006 - 11:23 AM

#8

My 05 450 seemed to loose a little after 75 hours, it had more blow by on the frame, I should have changed the piston before Mammoth. I ran my 450 in about 12 grand prix races with long straightaways where you are pinned near the rev limiter for a couple hundred yards per lap.
They say most 250F's loose performance after 25 hours.
To be safe I would change your piston between 75 and 100 hours depending on what kind of riding you do.

  • 642MX

Posted July 29, 2006 - 04:30 PM

#9

I replace the rings and cam chain once a year, and I replace the piston and valve springs every other year.

I replaced the valves last winter just to be safe, I adjusted them twice since I've had the bike and the center intake tightened up for the third time, so I replaced them all.

I don't have an hour meter, but I ride every weekend possible, a mix of MX and trails. I change my oil every ride and its always got a clean air filter in it.

  • DIRTRIDER-5

Posted July 30, 2006 - 06:35 PM

#10

:thumbsup: I own an 01 haven't had any problems just your normal maintenance brakes, tire,oil change after every two rides had never had to tare engine down for any big repairs one of the the best bikes i own by far hands down.





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