whats all the talk about yz426 motors breaking?

26 replies to this topic
  • jrspawn

Posted February 02, 2006 - 06:59 PM


Hey, ive ran YZ426 engine in a few of my Laeger,Walsh, and Houser hybrid quads. Ive had absolutely NO PROBLEMS that werent self inflickted. It is a vry great and reliable engine, would recomend a good port job(TC) to get a little more out of it. Im actually picking up another full Walsh quad with a Power roll stroked 426 to a 465, cant wait to get it.


  • bnio

Posted February 02, 2006 - 07:27 PM


These machines require maintenence and they are getting old. Many people who have had failures most likely didn't keep up with maintenence. I just bought a yz400f and the the bottom end was starved for oil (the idiot probably didn't bother to check the oil) overheeated the bottom end and destroyed to con rod. But the failure could have been from the oild pump which was damaged heavily and so on. What I am getting at is that these engines produce 2Hp per cubic inch which is very impressive and this also means they see elevated stresses within the motor from bmep, combustion tempertures, stresses on the oil from heat and pressure etc. These are race engines not the p.o.s. trail 90's and old tt600, xr600 four strokes. Thay also have dry sump oiling which throws in more concerns about making sure you oil pump is in good shape. These engines are dead reliable as long as you take care of them. Don't be afraid to pull your engine covers off check the oil pump for damage or wear and other vital components condition. Also want to mention that the seized bottem end (connecting rod) has happened in 400's and 426's, many people have posted on this site with this very problem.

  • rasta

Posted February 02, 2006 - 07:54 PM


02 426 -did nothing but change oil/filter air filter. still passes leak down tests-already on third engine on my 03 450

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  • 642MX

Posted February 02, 2006 - 08:25 PM


Also want to mention that the seized bottem end (connecting rod) has happened in 400's and 426's, many people have posted on this site with this very problem.

I remember reading about some 400's with rod problems, but not 426's.

  • kawirider

Posted February 02, 2006 - 08:32 PM


Why go through all the trouble of trying to buy the motor and cram it into the frame? The YFZ450 will be a lot better than your 400EX with a YZ426 motor. BTW the YFZ does have 5 gears.

  • getdrunk

Posted February 03, 2006 - 04:58 PM


the yfz450 cost to much. and the 400ex with the 426 motor handles better than a yfz. :thumbsup:

now my quad will be half yamaha n half honda. ill have the yamaha motor. and the yfz shocks. :bonk:

and its easy to get the motor in the quad. i found a mounting kit that mounts the motor in perfect. it even comes with a oil tank and airbox :thumbsup:

than all ill need to buy is the
head pipe
250r radiator

and only welding involved is
have to weld tabs on frame to hold radiator and
have to weld a pipe on to the header so it gors around the frame and connects to the muffler.

  • getdrunk

Posted February 03, 2006 - 05:01 PM


http://forums.atvcon...tos.cfm?ID=9478 pics of the quad

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