426 reliability

7 replies to this topic
  • BlackMercedes300e

Posted January 01, 2007 - 08:33 PM


I replaced a whole tranny on my 426. Three days later the motor siezed up. Dont even want to look at it yet. What i dont understand is why it would sieze why it was idleing.

I want to hear some stories like i've had my 426 for 7 years and never touched the engine.

Inspire me to keep it.............

i change my oil after every tank of gas

  • Terrain Rider 4z

Posted January 02, 2007 - 08:51 AM


My bike is now 6 years old and on stock piston and rings. No problems as of yet.....knock on wood. I know a lot of guys with 6-8 year old YZ-Fs that are still running strong.

  • TuningFork426

Posted January 02, 2007 - 08:42 PM


wow i hope my new top end lasts that long!

I opened it up, and found it dropped a valve, the valve is mended onto the piston and one of the cams is mutilated.

so the topend will be all new so everything on the bikes engine is new except the cam chain and the crank and rod.

  • Birdy426

Posted January 02, 2007 - 10:13 PM


At 7500 miles I pulled mine apart because the primary drive nut backed off, and dorked up the end of the crank. The bottom end was still really tight. The center intake valve was starting to tulip a bit, but all the others were good. The guides were still in spec, and the cylinder was just barely out of limits for taper. Te pd nut backed off because the previous owner forgot to bend up the tabbed lock washer when he was inthere doing something (no idea what...)

Several of my buddies have 400's/426's as well, and all are basically bullet proof.

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  • ISBB

Posted January 03, 2007 - 05:13 PM


bought my 02 new and havent had to do a damn thing yet.. allthough new pistons rings and top end inspection are probably due... that will be a summer job. :lol:


Posted January 03, 2007 - 05:18 PM


I also have had my 02 WR since new have not done anything to the motor or trans.Still running strong.

  • 642MX

Posted January 03, 2007 - 05:42 PM


No problems here. 426's are good bikes. :lol:

  • WildRide

Posted January 03, 2007 - 06:00 PM


My 01WR426F and my youngest sons 00YZ426F has been trouble free. The YZF will probably last forever because in 2000 the YZ426F's came stock with SS rather than Ti valves.


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