WR426 motor vs. YZ426 motor



6 replies to this topic
  • beengoneawhile

Posted June 12, 2002 - 09:30 PM

#1

Can anyone explain the differences in the 2002 WR426 and YZ426 motors? I know that the gear ratios are different (1, 3, 4, 5), but are there other differences that would effect the powerband, HP or torque profiles? I'm going to buy 1 or the other within a couple of weeks and would like the WR gearbox, but not if there is a big difference in the engines.

thanks ahead of time

  • 98yz

Posted June 12, 2002 - 11:25 AM

#2

I am not the most knowledgable on all of the differences, but to name just a few.

Gearing is different, primarily in 1st and 2nd.
Timing is different for the motor.
Typically rear spring rate is softer on the WR
WR has 18" rear rim and YZ has 19"
WR has air cut valve on carb, YZ doesn't.

Somebody help with more.
Evaluate what it is you are going to be riding. I have not riden my YZ anywhere that I found a WR might be better, but I have not encountered everything. I think it is easier to adapt the YZ to off-road/woods, than it is to take the WR to the track.

Best of Luck and Both are great machines

  • Hick

Posted June 12, 2002 - 11:44 AM

#3

As far as I know the motors are identical with the exception of the gears and the cam timing, with the latter being very easy to change to the YZ spec. I also heard the WR has a slightly lower rev limiter, but I don’t know if that is the case for the ’02 model year, and actually don’t know this to be true for any year…

The jetting is very different, I think only the needle (and PAJ) is changed but it is still a large difference, IMO this is due to the restrictions placed on the motor in the form of air box lid and small exhaust (both also cheaply and easily changed to a psuedo-YZ state).

The carb also has what is called an Air Cut Valve, this has given a few people jetting problems because it leans things out at lower throttle settings. Again, this is easily disabled, so in a few minutes and with a few dollars you could make a WR run exactly like a YZ.

The thing you need to base your decision on then is the gear box. First gear in the YZ is very tall, taller than most other MX bikes. This can make it a handful in tight going. Fifth gear is very tall in the WR, about 14% taller than the YZ, so if you aim to do any dual sporting you may want the WR…

Just about every other WR vs. YZ difference is easily changed, with the only big ticket item being replacing that wacky WR seat and tank. I’m 6’1” and it feels like that tank is in my lap…

But it sounds like you will be getting the WR.

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  • beengoneawhile

Posted June 12, 2002 - 11:46 AM

#4

Thanks for the info. After I posted, I kept on reading. From different threads I pickup on the timing issue and the carb. I'm getting back into dirtbikes after an extended break (14 years, I can't believe its been that long), but used to race MX and hare scrambles. I've resurrected my last bike, an 85 RM250, and have been riding for about a month. I too have prefered MXers to WRs in the past although I owned and raced both (Husky's prior to the RM250). Thanks again.

  • beengoneawhile

Posted June 12, 2002 - 11:57 AM

#5

Hick,

Thanks for the reply. In the past I've just dropped a tooth or 2 on the front to bring first down to a reasonable level for woods riding (on the MXers that is), but I was only doing that because I liked the powerband on the MXers so much more than the generally tamer WRs. If the WR's motor is (or can be) similar to the YZ, I think you're right, I'll buy the WR.

  • nooffseason

Posted June 12, 2002 - 12:26 PM

#6

Don't forget the heavier flywheel! It makes it rev slower, but alot of times that is a good thing.Also comes with the o ring chain. I am back from a 12 year lay off and I also did some motorcross racing. I bought the WR did the free mod's (no YZ timing)Clarke SDG seat tank combo and love it!

  • SoCalWR426

Posted June 12, 2002 - 07:36 PM

#7

02 vs 01 models.. Remapped ign, carb fine tuning no BK needed, bigger brakes and rotors to stop better, moved the swing arm pivot. + what everybody mentioned above.

SoCal




 
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