more valve curiosity....


13 replies to this topic
  • gbalias

Posted March 08, 2007 - 08:12 PM

#1

ok, so i checked the clearances on my valves for my 1998 yz400.

i was curious....

i noticed the dealer only carries shims/pads in .05mm increments, as well as aftermarket brands. i checked bikebandit, ronayers, TT store....all were .05mm.

now, when i checked the pads that were in there, they were in .01mm increments. for instance i had a 176, 174, 180 pad in there. so by my super-power deductive reasoning, is it possible that these are the original pads from factory assembly?

the kid i bought the bike from a few years ago said that he had the valves checked and they were good and no shimming was done. i just find it hard to believe that after 9 years, they are still in spec.

if so, good job Yami!!!! :applause: :lol: :lol:

any ideas?

  • rexbond007

Posted March 08, 2007 - 08:50 PM

#2

ok, so i checked the clearances on my valves for my 1998 yz400.

now, when i checked the pads that were in there, they were in .01mm increments. for instance i had a 176, 174, 180 pad in there. so by my super-power deductive reasoning, is it possible that these are the original pads from factory assembly?


not nessarly, but possible, the only things that cause the need to re-shim is springs and valve wear. and the major factor in this wear which rapidly accelerates wear is overheating the bike. which softens up the valves taking the hardness out of the titanium and the strength out of the springs. if you change oil, do everything right to look after a bike you may be the first person to re-shim this bike.

  • gbalias

Posted March 08, 2007 - 09:01 PM

#3

sounds promising. im meticulous about maintenance so i hope itll last for years to come.

i was just wondering the expectancy of valve tolerance life.

  • YZ426F Rider

Posted March 08, 2007 - 09:15 PM

#4

I would bet they are the original shims.

  • 426pilot

Posted March 08, 2007 - 09:30 PM

#5

I've been riding my '00 yz426 since day one and have never had to re-shim. I check the clearances once a year and they are always dead on. I figured I was doing something wrong so I took it to our local dealership last Fall to have the clearances checked... they were perfect. I don't know what Yamaha is doing to make steal valves hold their shape so long, but it's working.

  • moontana

Posted March 08, 2007 - 09:46 PM

#6

I have a 06yz450f and after hearing all of this I dont even think Iam going to touch the motor on mine this whole racing season we just finished round #1 this past weekend. I just have 15.6 hours on it according to the DRD hour meter.

  • gbalias

Posted March 08, 2007 - 10:44 PM

#7

well....apparently theyve got something right. theyre titanium valves btw.

way to go blue. heheheh. i just talked to a buddy of mine whos having issues with his crf valves. HAHAHAHAH.

at least i know i dont have to worry about it. just think, 9 years and still all good. ive even done an endurance desert race. woo woo

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • jayh300

Posted March 09, 2007 - 07:58 AM

#8

i bought a used 99 yz400f about 6 months ago. got the manual. in the back the original owner had wrote in each time he checked valves, there is never an entry for re-shim. I put a cam chain in it in december, have been told it is a wear item on these, and mine are still in spec. starts easy, tons of power !!!!
pretty impressed.

  • grayracer513

Posted March 09, 2007 - 09:40 AM

#9

well....apparently theyve got something right. theyre titanium valves btw.

way to go blue. heheheh. i just talked to a buddy of mine whos having issues with his crf valves. HAHAHAHAH.

at least i know i dont have to worry about it. just think, 9 years and still all good. ive even done an endurance desert race. woo woo

All YZ400's were built with Stainless Steel valves, not Ti. If you're basing your assumption that yours are titanium on a magnet test, the magnet won't stick to the high grade SS used in the OEM valves either.

There are two possibilities on the finding of shims in .01mm increments. One is that the valves were adjusted by a shop mechanic who used shims he had in his personal collection from a previous job, which is fine, and happens all the time, at least to the extent that the valves ever get adjusted on YZF's. The other is that those are the original factory shims. And no, that really wouldn't surprise me. There was a time when it would have, but not any more.

  • gbalias

Posted March 09, 2007 - 12:11 PM

#10

All YZ400's were built with Stainless Steel valves, not Ti. If you're basing your assumption that yours are titanium on a magnet test, the magnet won't stick to the high grade SS used in the OEM valves either.

There are two possibilities on the finding of shims in .01mm increments. One is that the valves were adjusted by a shop mechanic who used shims he had in his personal collection from a previous job, which is fine, and happens all the time, at least to the extent that the valves ever get adjusted on YZF's. The other is that those are the original factory shims. And no, that really wouldn't surprise me. There was a time when it would have, but not any more.


i was responding to 426pilot. obviously he's got a 426. :lol:


:applause:

  • grayracer513

Posted March 09, 2007 - 12:46 PM

#11

Oh. Well, fine, but the 2000 model 426 was also equipped with SS valves.

  • mkporn

Posted March 09, 2007 - 12:50 PM

#12

Oh. Well, fine, but the 2000 model 426 was also equipped with SS valves.


Yep.... Make sure your i's are dotted and your t's crossed or Gray will catch ya^^^^^:applause:

  • gbalias

Posted March 09, 2007 - 04:28 PM

#13

clearly.
i must not have enough free time. hehehe.


ill head back to the DRZ forum.

  • grayracer513

Posted March 09, 2007 - 04:40 PM

#14

i must not have enough free time.

I know I don't :applause:





Related Content

Forums
Photo

Megabomb Fitment by 288yz450


Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply
Forums
Photo

Snake pit oct 30th by The Anvil


Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  293 replies
Wiki
WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info


Articles
  • 0 replies
Forums
Photo

Michigan Motocross Tires by 288yz450


Dirt Bike   Dirt Bike Regional Discussion   North
  • 1 reply
Forums
Photo

Is it worth it? (Cam and High compression piston) by macgi77


Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies
 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.