tranny on my yz 400 going?


6 replies to this topic
  • Needpowder

Posted August 23, 2004 - 01:03 PM

#1

I have a 99 yz 400. My problem is when I use third gear, I hear a loud ticking noise. I can also feel the vibration slightly. It is most apparent at low rpms in third (only under load). It is the worst going uphill (in third) at low rpms. I just replaced the chain thinking that might be the problem. Didn't help. The bike seems fine in every other gear. Is my transmission going out? Any input would be greatly appreciated. Thanks.
chris :thumbsup:

  • motocrosschump

Posted August 23, 2004 - 01:17 PM

#2

I have a 400 motor I will sell you, but 5th gear is gone. :thumbsup: lol

  • trailriderjoe

Posted August 23, 2004 - 01:52 PM

#3

OH what fun it is! (I wiped two teeth off 4th wheel gear).

I only noticed it on pavement or during mild acceleration on hard pack. And I'm talking two teeth totally gone, as in all thru the oil pump and pickup screen!

It's real easy to confirm the third gear failure.
Put it up on the stand, pull in the clutch and roll the rear wheel backwards, as you shift it thru the gears.

Rolling the wheel backwards will load the leading edge of the gear faces. When you get to third you'll see the chain hop a bit and feel it in the wheel.

It's not a terrible job to split the cases (if you're into that kind of stuff). I ended up spending around $130-$140 for three different gears I replaced. BUT...WAIT...THERES MORE...Why stop there? Fresh piston, rings, gaskets, seals etc.....It is 5 years old right? :devil: :thumbsup:

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  • Needpowder

Posted August 24, 2004 - 09:24 AM

#4

Thanks for the reply. The test was easy, like you said. I can definitely feel it in third gear. 1st sounds a little rough also. I guess I have my work cut out for me huh? Any advice before I get started?
I was also wondering what you thought about riding it. I just changed the oil and filter, and there was a decent amount of metal in the filter(a little more than usual). I would love to get a few more rides in before I tear it apart though.
Thanks for the help. :thumbsup:

  • Hamish

Posted August 25, 2004 - 04:39 AM

#5

when my box died and I stripped it down there was a chunk of gear sitting in the sump. Was lucky that it didnt get caught up in anything. I'd put a rod in it and do a valve & seat job while you have it apart, and pay particular attention to the shift forks.
Piston/rings as required. Then she'll be ready for another 5 years hard labour :thumbsup:

  • tool

Posted August 25, 2004 - 10:11 AM

#6

Any advice before I get started?
I was also wondering what you thought about riding it. I just changed the oil and filter, and there was a decent amount of metal in the filter(a little more than usual). I would love to get a few more rides in before I tear it apart though.


so you ARE crazy. do you know why there is only a decent amount of metal in the oil filter? that because theres a big screen that the oil goes through before it reaches the filter. thats where the big pieces are, or they are floating around your bottom end.
a few more rides? your crazy. why not just open the clutch cover and drop a few drywall screws in?
drain the oil and tear her down... it will be good for the both of you.

  • trailriderjoe

Posted August 30, 2004 - 04:36 PM

#7

Tear it down!
Hamish is right.
When I got into mine, the main pickup screen for the sump was loaded with the "larger debris" or should I call them "TEETH".
It's not worth the damage it can REALLY cause!
You make the filter (and chance that it can't) catch all the debris, not to mention the pump is seeing everything the screen passes.

Just remember, before the finer debris gets to the filter it goes thru both pumps: scavenge & high pressure. FIRST!


Keep us posted on the surgery!





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