YZ or WR timing question

13 replies to this topic
  • Captain Bob

Posted October 13, 2005 - 05:50 PM


Hi folks, I am new to Thumpertalk. I recently quit road racing and traded my road racer for a 99 WR 400 and some cash. The WR has all mods done and is YZ timed. I am surprised at how much power the WR has. Although, I am still new to the bike, sometimes it seems to have a bit to much power for tight new england trails. My question is....

Should I just continue to ride the bike the way it is, get the suspension better dialed in and try to get used to it? or, should I bring it back to WR timing. I do like the motor but sometimes feel it is a handful in the real tight stuff.

I am an older guy who used to MX years ago (read as decades). I would not call my self an expert on the trails. It has been a while since I have been dirt riding but really want to get back into it.

I am working on getting the suspension a bit softer as well. It was set up as a MX'r although, never actually raced. Appreciate any thoughts you may have on the subject.


  • ARin

Posted October 13, 2005 - 05:56 PM


i woud personally prefer the WR timing for trail riding...but that doesnt mean you SHOULDNT get your suspension dialed in ALSO.

  • Captain Bob

Posted October 13, 2005 - 06:35 PM


Appreciate the thought. If I change the timing back to WR, would you know if I need to rejet the carb?


  • dbailey223

Posted October 13, 2005 - 08:00 PM


From what I have read here, I believe yes, you would have to rejet or at least adjust the carb.

  • Math

Posted October 14, 2005 - 05:08 AM


The guy from who you bought the bike might have switch his carb to YZ jetting (smaller pilot, richer jet needle, smaller main, bigger pilot air jet, shut air closed valve, richer starter jet...). That might not work properly with WR timing. It is always a good thing to at least know what your jetting is. Take your time, have a look at what your jetting set up is and I'm sure you'll be glad you did.

To me the YZ timing is more exciting even in the trails... You can go back to WR and see how you find it... Or even better, try to find someone who can make you try the WR timing... then it's gonna be easier to take the decision as to whether or not you want to try the switch to WR timing on your bike...

Play with your suspension a lot... get used to it. They are great and your riding will be much easier if you have them set properly compared to not. There is a good article in the technical article section of TT that will help you set your sag at first.

  • Rich_in_Orlando

Posted October 14, 2005 - 05:18 AM


I ran my '99 with YZ timing for a couple of years but went back to WR timing and I'm sticking with it. WR timing suits tight trails much better than YZ timing, IMO. Much smoother low power and less clutch fanning required. WR timing seems to lug a lot easier than YZ timing does. However, if I were concerned about getting holeshots I might think differently.

I recommend for WR timing to put the carb specs back to stock. If I recall correctly, that's a 168 main, 42 pilot, DTM needle. My carb had been deoctopussed so the start jet was changed to a 60. Pilot air jet is 75 and main air jet is 200 (I think). Check your owner's manual to be sure. With WR timing and everything else stock except for a GYT-R exhaust insert, the bike runs great over a wide range of temperatures and altitudes. (Hot summers in Florida woods to 5000 + feet in the Appalachian mountains.) Have fun with the new bike. Mine still rocks.

  • gmoss357

Posted October 14, 2005 - 05:24 AM


When they changed the cam timing did they put a auto decompression cam in? If not, I recommend it.

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  • Math

Posted October 14, 2005 - 06:07 AM


Yeah, I've kickstart a WR426 equipped with a 450 cam and that is sweet.

To come back on what Rich said, my YZ timing probably does not have as much impact since my gearing is 16/48. This kind of high gearing loads the engine pretty much and probably eliminates, at least in part, the bad sides of YZ timing in the trails... like hard hits. As for the clutch thing, we don't do so much log crossing and rock climbing here so... If I would, I'de go back to a 14-50 gearing and would probably stay with WR timing... Depends on what your riding conditions will be...

Rich seems right on the jetting. The stock 01 WR 426 jetting was 42 pj, DQR needle#4, 165mj, 75paj, 200maj, 65 starter jet. The stock YZ426 setting is 42pj, EJP needle, 162mj, 72 starter jet, 100 paj, 200 maj. Another important difference is that the WR has an air cut valve whereas the YZ does not. The WR air cut valve can be shut when you do YZ timing to mimic the YZ carb so check if yours still has the stock setting. You can read about the air cut valve on thumperfaq.

  • Captain Bob

Posted October 14, 2005 - 06:27 AM


Thanks guys for all the input! I am going to dial the suspension in first then go from there. I have a new rear shock spring coming in hopefully Monday.
(Anyone need a Race-Tech 5.6kg spring?)
Anyone in Mass with a WR timed bike I could try? I will try to check one out first before making the switch!

Thanks again!


  • dbailey223

Posted October 14, 2005 - 12:37 PM


Fly to Vegas--yuo can try mine--heck, Vegas alone is worth the trip! 80 some degrees today, low humidity, casinos, ......

  • Rich_in_Orlando

Posted October 14, 2005 - 12:46 PM


Math, where's this thumperfaq of which you speak?

  • Rich_in_Orlando

Posted October 14, 2005 - 01:10 PM


Never mind- I found it : www.thumperfaq.com.

I had been looking for info on the ACV- now I've got it. Thanks!

  • Math

Posted October 17, 2005 - 07:31 AM


Sorry Rich, I did not answer your question been out of TT for the week-end.

You can find many answers on thumperfaq :banghead: . Remember that everything that's written there concerns the 250f... :banghead: most of the time (if not all the time) you can cut n paste directly to the 426f situation .

Glad you found what you need.


  • kensum90

Posted June 30, 2006 - 07:06 PM


What is the procedure for setting the timing on a 2002 yz426f?


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