98 YZ400F newbie question


7 replies to this topic
  • ahrma73j

Posted January 17, 2007 - 07:45 AM

#1

I am new to the watercooled 4 stroke world,always had 2 strokes and still race them in vintage MX,are there any know problems(other than being heavier and older) with the 98-99 YZ400F? .I recently swaped a bike for a real clean used one and want to now what to look for or change out now before any problems,Thanks for any help.

  • tom nolan

Posted January 17, 2007 - 10:33 AM

#2

I have owned a 98 YZ400 since new and I am still in love with it. Getting the proper gearing is the most inportant thing other than regular oil changes. It has balls and is as relibable as a stone. Good luck

  • rdefonce

Posted January 17, 2007 - 10:36 AM

#3

I am new to the watercooled 4 stroke world,always had 2 strokes and still race them in vintage MX,are there any know problems(other than being heavier and older) with the 98-99 YZ400F? .I recently swaped a bike for a real clean used one and want to now what to look for or change out now before any problems,Thanks for any help.


Congrats on your "new" YZ!
I'm not sure about the '98, 'cuz I've got the '99 version, but watch the guard that protects the swingarm from the chain. The guard moves around too much and will wear the swingarm from the excess movement. I saw one post here that showed cracks in swingarm because of this.:-o

Watch out for dry steering head bearings. It gets hot there because of the oil, and the grease could get hot and run out.

I bought my YZ new in '99 and still got it. It's super-reliable, with the steel valves. I have low hours on mine, and believe it or not, my valves are still withing spec . . . haven't needed adjustment yet!

This bike is one of the most reliable dirt bikes I've ever owned.

  • motofox2007

Posted January 17, 2007 - 06:13 PM

#4

I have a 1999 yz400 does anyone know how often i should do the piston and rings if im not racing it.

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  • rdefonce

Posted January 18, 2007 - 06:15 AM

#5

I have a 1999 yz400 does anyone know how often i should do the piston and rings if im not racing it.


It depends on how religious you were with oil changes/air filter maintenance. I change my oil about every 3 - 4 hours of operation. I estimate it's got 125 hours on it and the piston/rings definitely don't need changing; they're original.

If you go a long time between oil changes, piston/rings will need swapping out sooner rather than later. . . . and if you're not running it hard, that will increase intervals a bit too.

  • MDS55

Posted January 18, 2007 - 11:23 AM

#6

I've had my 99 for about 8 months. It's great, love it. I change the oil and clean the air filter every 3 rides. I have not had any problems with the bike at all. I would recommend water-wetter in the radiator, it definitely helps it run cooler.

  • PumpkinHumper

Posted January 18, 2007 - 04:32 PM

#7

Replace the timing chain NOW if it hasn't been done. While you have it apart drop a new piston and rings and adjust the valves.

Change the oil, brake fluid, coolant, and suspension fluid and you are good to go.

Oh and greese the suspension linkage, brake pivot, and steering stem bearings.

You can usualy go 2+ years before having to do a top end if you are just a casual trailrider. Those bikes seem to just run forever.

  • Jekel

Posted January 20, 2007 - 08:45 PM

#8

If you are going n to the top end and replacing stuff, get a auto decomp cam. Best investment into my 99 WR400 for starting.:lol:





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