WR / YZ 400 Valve Adjustment??????

13 replies to this topic
  • WR_Jason

Posted June 28, 2001 - 06:46 AM


Hey Thump Chumps, its good to see everyone is home! THANKS BILL :). I suppose you are all wondering why we are all gathered here today :D . I would like to know how many of you have actually had to adjust your valves. If so, how many hours or miles and how frequently. Also, the book says to drain the coolant and remove the Radiators???? I don't see an obstruction there, is this nessecarry? I was going to check mine and was thwarted by Yamaha and their cleaver Allen head rounded off motor mount bolts after stripping one out,,,, Grrrrrrrrrr! Anyway it was getting late and I was riding the next day and couldnt find my drill bits so I bagged it. I will check them the next time I get the bike real clean and have some down time, unless they are know to get tight or get out of tollerance alot. The bike had 600 miles on it when I got it and the previos owner has proven to have overlooked some mechanical details like bolting the dampening rod to the end cap in the fork!
Thanks guys!

  • MN_Kevin

Posted June 28, 2001 - 07:43 AM


My initial valve inspect found THREE valves out of spec (OOS).

'99 WZ/YR (you choose!) with ALL YZ mods, de-octopused, DSP Doug Henry airbox w/ velocity stack, FMF PowerBomb header, Stroker SX-1 silencer, SS front brake line, forked over by Pro-Action (and then fixed by me), OEM YZ tank, IMS YZ seat, gray wire severed, carb mods by Jim Dean, Andy in OZ, & Sir "Taffy" from Jolly Old England, AMA, NESC, and I use MOBIL 1 Oil, with ZERO problems.

  • Elian

Posted June 28, 2001 - 01:37 PM


Hello... I don´t race my bike, Only tours (so much). I adjust the valve clareance at 1000 km(600 mile so so). There was three out. You don´t need to take off the radiator!.
Good luck.

  • Carl_Youngstrom

Posted June 28, 2001 - 01:53 PM


I have a 2001 WR. I checked mine at 500 miles, all were within spec. I do not race, only trail ride. My manual does not mention anything about the radiators, but says to remove the carb, which I did not do and had no problem.


  • WR_Rider

Posted June 28, 2001 - 02:20 PM


Adjusted them at about 250 miles (2 exhaust and 1 intake). i've checked about 2 or 3 times since then and all are still within spec. I've got over 1000 miles or so on her now. left the radiators on and the carb on.
Be sure to clean the wire harness above the head before removal or wrap a towel around it to prevent dirt from falling off and into the top of the motor!!!


  • samohT

Posted June 29, 2001 - 01:18 AM


The first time I checked my valves all the intake valves needed adjustment. They are still within spec a year later. But now my exhaust valves needs adjusting.

A tip when removing the top motor mount:
Don't try to unscrew the allen-head screw, instead unscrew the 12mm nut on the other side while just holding the screw. If that was what you did then I apology for being silly.

  • Bill

Posted June 29, 2001 - 01:32 AM


With the help of some friends (mcarp, mike68, NH Kev, npuza, THANKS :)) I changed my bike to YZ timing. The only parts that have to come off are:

vent hoses at valve cover
upper motor mount
spark plug cap (only off the plug)
valve cover


PS The THANKS goes to Bryan, it's his site. He just let's me hang out here :D

99 WR400f, YZ timed, MX-Tech suspension, Scotts steering damper, White Bros E-Series (12 discs), tapered header and a/f. Kouba T-handle for the fuel screw. Works Connection billet throttle tube and frame guards. Cycra Pro-Bend, triple clamp mount handguards. Thumper Racing rad guards, Renthal Jimmy Button highs, YZ Tank and IMS seat, YZ number plate, odo removed, EKP, 48PJ, 175MJ at 500-1000' Thanks James Dean!

[This message has been edited by Bill (edited 06-29-2001).]

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  • Rich_in_Orlando

Posted June 29, 2001 - 02:18 AM


All good advice so far, and Chuck's post reminded me of something. Chuck suggested cleaning the wiring harness or wrapping a towel around it to keep dirt from getting in the motor. I seem to recall reading somewhere that saran wrap around that area does a good job, too, and is a little less bulky than a towel. Next time I open the valve cover, that's what I'm going to do.

  • WR_Jason

Posted June 29, 2001 - 05:46 AM


Cool, thanks team, Yup I use the saran wrape my self, works great, plus I hate cleaning :D . It sounds like alot of these are either out from the factory or after break in. Ill bet its at the factory. Well Ill check em and forget em probably. Oh yeah I know not to try to turn the bolt. It was just balls tight and spun the bolt too :) .

  • olson_jr

Posted June 30, 2001 - 02:48 AM


Gentlemen, are you finding the valves that are out to be tight or loose ?

  • Vic

Posted June 30, 2001 - 05:31 AM


When I had my bike changed to YZ timing, I had the valves inspected. My exhaust valves were tight right at the high end of the spec. chart. My intake were right in the middle. Nothing was adjusted and I was told it didn't need to be.

I believe-in my mech., and I was told if they are in the spec. range to leave them alone.

  • WR_Jason

Posted June 30, 2001 - 07:38 AM


Hmmmm, It dose not look like any one has to adjust them more than once after break in. I wonder if you guys finding exhaust valves tight are running the 01 TI valeves? There seems to be some speculation that the TI valves are causing some trouble on the exhaust side as per Honda using TI intake but regular exhaust vales in the CRF . I am asumeing the valves that are out of tolerace are tight?

  • MS

Posted July 01, 2001 - 06:43 PM


I bought my 98 with about 700 miles on her. checked the valves after about another 300 and intakes and exhaust were tight.. I race some motocross and enduros... I have run her another 6 months and just checked them this weekend, no further adjustments needed, all within spec...

you do not have to remove the radiators, but you might have to take out the radiator mounting bolts and move the radiators.. also, do not forget about the compression lever if you do have to pull the cams to adjust your valves.. good luck onthe engine mounting brace, you will not be able to adjust until you get that sucker off.. Hmmm , sounds like a good time to buy some anti-seize..


  • WR_Jason

Posted July 02, 2001 - 03:50 AM


Yup, I got the never seize ready and waiting. The guy that had the bike before me was wrench happy. He even had the piliot screw in the carb torqued down tight! Ill probably do the check this week. Ill just drill the head off the allen bolt. I am going to replace em all with hex ones then.


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