Who's Changing Out Top Ends?



7 replies to this topic
  • RichB

Posted November 21, 2001 - 04:38 AM

#1

Hey guys,

How often are you guys replacing the top end in the 426. I bought a used 01 and DO NOT want to pay the expense of fixing a blow up on a thumper. Am a little bit nervous from coming off a 2-stroke where I knew to replace my top end once a year (never blew up a bike in over 10 years). How do you tell when it's time, other than waiting for a catestrophic event.

Thanks

  • Glen_T

Posted November 21, 2001 - 05:36 AM

#2

I replaced mine after 2 years. General principles. Piston was a bit worn, but could have gone longer. This bike gets an average of two solid rides a month. (wish it could be more)

GLEN

  • Greg

Posted November 21, 2001 - 06:42 AM

#3

I have approximately 100 hours on my 2000 426 and it is still going strong. I regularly change my oil and service my air filter. I think the compression test is the best method to determine top-end health, without taking your engine apart.
Hope that helps.

  • MikeOK

Posted November 21, 2001 - 01:27 PM

#4

100+ hours here, still stock and good compression. I think I'll try for one more season. I have some other mods to do this winter...

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  • Shawbridge Husky

Posted November 21, 2001 - 01:57 PM

#5

About top end : I am embarassed to say how many HOURS it took me to slip piston / rings into cylinder. Anyone out there have a trick for doing this easily? ( please no perverted comments ! ) :)

  • PK

Posted November 21, 2001 - 05:49 PM

#6

I replaced my piston and rings in my 99 YZ400 because I had bought the bike used in 2000 from a guy who did alot hare scrambles so I wasn't sure what the motor was like on the inside. It ran great but to be on the safe side I tore into it. I was very surprised, the rings and piston were still in spec. You could still see the cross hatching in the cylinder, it would have gone another year. I replaced the piston and rings because I already had them and the motor was already torn apart. I also had to install a larger shim on one valve as it was getting close to the bottom end of the acceptable range. It took about an hour and a half longer to do my 400 as it does to do my wife's YZ125 top end. I would do a compression test before you tear into the bike, as was stated earlier, it is a good way to tell how the top end is doing.

Pat

  • Glen_T

Posted November 24, 2001 - 07:13 PM

#7

Hey Hugh,

Lots of sweat, swearing or a big hammer! I'd like to know the trick too.

GLEN

  • Rusty

Posted November 25, 2001 - 04:53 AM

#8

Hello, I'm new to the discussion forum. I have a 98 400 and I'd like to check my compression but don't have the specs. Can anyone tell me what kind of numbers I should be seeing.
Thanks
Rusty

P.S. Rusty isn't my name, it's my condition. Just getting back to riding after a 15 year layoff. Can't believe I stayed away from it this long.





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