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gbalias

more valve curiosity....

14 posts in this topic

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?

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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.

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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.

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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.

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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.

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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

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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.

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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.

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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:

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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:

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clearly.

i must not have enough free time. hehehe.

ill head back to the DRZ forum.

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