We may have '04 450s problem/defect???

2 of my friend, one with yz and another with wr lost all the oil due to leaking countershaft seal(behind front sprocket)! The engine even seased on one of the bikes.

I hope yamaha did not made seal spring longer to gain 0.01 hp, on the price of seased engine!

Just a warning to keep an eye on it!

i've noticed that the chain tension is touchy to adjust,its very easy to overtighten and the sweet spot is very narrow. i found myself overtightening to overcome the chain slap. now i have siliconed the chain slide and its not as much an issue.maybe tightness is the culprit? :devil::thumbsup:

Ditto on the heavy silicone under the chain slide guide! Mine is set 1/2" thick and I get no chain slap. The 03's have not had this problem and most likely they got a bad batch of seals at the factory install. Bad luck is most likely the culprit. Mountain man is right about the chain tension setting but most people keep that right on spec. :thumbsup:

300 miles here on my 04 WR450 and not one single problem :thumbsup:

Hey, I've got about 11 miles on my 04 WR450F and no trouble here either! :thumbsup:

The fellow with the yz uses powerwash every time and I thought that maybe he inserted some dirt in the seal, as when they dissasembled the engine and removed the seal they said that there was a LOT of dirt in it. they even did not changed it, but only cleaned it and put it back. The problem is that the fellow with the wr uses ONLY garden hoose to clean the bike :thumbsup:. Maybe chain tension is really the problem. Is there any way to remove the seal without destroing it? I wander if there is dirt in mine. I for sure never overtiten my chain, and never use powerwash! This will be a good test if I can remove my seal and check for dirth. If I have to order new seal I'll have to wait for it at least a month :devil:

BTW the wr is at about 1500ml with allmost no muddy riding.

Hey, NCMM & Indy, what is this you guys are talking about with silicon-ing the chain slider? Got Pics?

i have a t.m. designworks chain slider and ran silicone under it where it contacts the swingarm top and bottom,then tightened it down. it would work on the stock unit also,just make sure it is in place before you silicone it or you will make a big mess tryin to get it in! :devil::thumbsup:

Forgive my ignorance, but how does this help? Is there a problem with the stocker flopping around or something?


My bike is an 01 426, but I dont believe Yamaha have fixed this problem as yet. The chain slider is designed to be able to move around slightly. I assume this is so the wear marks always line up with the chain. The problem is that sand and grit get under the chain guide and wear out the swingarm. My bike has almost 1mm worn out of the swingarm. I took a piece of rubber about 2mm thick and stuck it to the swingarm with sikoflex. The I put more siloflex on the top of it, then installed the chain guide. This prevents dirt from getting in there. This also helps where the chain guide goes over the weld on the top oif the swingarm. The chain wears through the guard in this high spot, and then starts chewing into the swingarm. Keep an eye on this.

Regarding the leaking seal:

IMO for an overtighterened chain to cause a shaft seal leak the bearing would have has to have been stuffed. The bearing holds the shaft in position. The bearing has minimal clearance (lets say 5 thou for arguments sake). The seal will easily still work with 5 thou of shaft movement.

Hamish is right your swingarm will wear thru if you dont put rubber or silicone under and chain slider. I have TM unit but it needs the cushion under it as well. :thumbsup:

Ahhh, now I get it. Thanks for the info guys. :thumbsup:

I dissasembled the WR with the supposed oil leak, but there were no problem. The fellow just did not know how to check his oil :thumbsup:. I dismonted mine also and everithing is clean. So sorry for the missleading info! I guess the fellow with the yz did something with the powerwash and insearted dirth.


Do you know someone who actually has worn down swingarm? I know it looks not good about this wear marks, but maybe it is not so big problem?

Do you have some pics of the mod??

I thought that might be the case. Thanks for posting the facts Sabin. :thumbsup: The 04's should be as good or better than the 03's for reliability. :devil:


Do you know someone who actually has worn down swingarm? I know it looks not good about this wear marks, but maybe it is not so big problem?

Do you have some pics of the mod??

Heres a couple links explaining the fix, they both have pictures.



I just fixed mine last night (I used Black RTV silicone adhesive and hammered the "tophats" down so they pinch the slider better.

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