1999 Yamaha WR400F Transmission Problem? WTF...

My friend has a 1999 Yamaha WR400F which by it previous owner had a hard life. Anyhow, my friend had finished doing the conversion modifictions to YZ specifications, so he was pulling wheelies up and down a long stretch of road to check the jetting and said it kept hoping out of third gear. So he tried it again just around our yard at work, when the bike is in third gear or shifting between third gear there is a horrible sound sort of like screetching or grinding noise :bonk:.

Can you guys shed any light on it? :thumbsup:

It is my friends form of transport to work so taking it to pieces it pretty hard leaving him with no transport, but he has never had this problem before until today. He rides the bike properly, I am begining to think the abuse it suffered in the hands of it's previous owner are really begining to show. :thumbsup:

Thanks in advance

Regards Honda0001

Comeon guys help me out here!

I know little about gears, trannies, etc., but sounds like this one is a gear issue and you're gonna have to break her down and find what is broken in there.

I had 3rd go out on my 2000. 3rd is a gear most often riden in so it usually goes first. Think of like the back sprocket on a ten speed bike, which ever one your ride in most gets the most wear and just like that sprocket they wear out over time. The others might be fine, but I wouldnt ride it, as you may cause more damage. Good luck.

the last two rides ive been on my third is hard to shift into, sometimes taking two or three trys brfore it will go. No resistance it just wont grab the gear. I think mine is starting to go to. Anyone else have this problem? What was the outcome clutches???

this same thing happened to me on my 04. it is caused by shifting with out the clutch at the wrong time. on mine it ground the shift fork down and screwed up two gears and the shift drum. fix it as soon as possible because it will get more expensive if u let it go.

I've got a complete 99 YZ400F transmission for sale - put a WR gearset in my YZ at about 500 miles so it's like new. PM me if anyone is interested

Sounds like bent shift forks or worn dogs and slots on the gears. Probably about 150 bucks in parts. Lots of labor hours if the shop does it but if you are mechanically inclined it can be done in one day in your home garage. In my experience, (I've split the cases at least 5 times since 2000) once the engine is out of the frame it's about an hour to take the motor apart and about 3 hours to put it back together if you have the right tools.

Here's a thread I posted a few years ago about this problem:


I had the same problem but in 4th and slipping back to 3rd. sounds the same though. I am moderately inclined so I thought I'd try to investigate my self. I had the manual and followed along. The money I saved In labor more than paid for some new tools Torque wrenches and such.

It ended up being a compilation of small problems that would not have been a big deal by them selfs but combined they were the root of the problem. First I removed the motor and Tran I tore the whole thing down valve job new piston. Then to the root of the evel so to speak. split the Tran. The dogs between 3rd and 4th were worn a bit so I replaced them also 1st was hurtin 5th wasn't too happy either all dogs problems the gears (teeth were fine). also there is a segment on the shift shaft that was worn so it went too. All in all I drooped 500 bucks on it and it is great now. Just a little patience and time it was real easy to do. The book says it all. Be prepared to wait a week for 3rd it came from Japan.Take lots of pic's for reference it was a great learning experience.

I hope this helps to not scare you away from trying your self. But it is an all day job.

yeah my friend has it in pieces now as we speak checking it out...

Thanks for your feedback...

Good luck with your porject. I just rebuilt my buddies dr407 which we had to split the caes on. Not as bad as you night think. Just take your time and forsure have the manual around. Out :thumbsup:

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