WR450F Stator Fault (*2003 model)

Check your WR450F rotor / stator retaining bolts as I recently had the misfortune of them coming loose on my 9 month old bike, which in turn demolished the stator, rotor, crankcases, starter journal etc. (Originally I had the woodruff key sheer within 100Km of running the bike in when new. The woodruff / engine was repaired & checked by my dealer & the bike ran OK (but noisy) for a further 800Km. It was in again twice after to investigate a "loose noise" but again nothing was found. To my amazement 3 days after the last check my engine failed due to a demolished stator etc caused by the retaining bolts sheering / slackening off. The cause of this? not being torqued up sufficiently / bolts being long enough. When this happened 3 of my mates with 03 WR450F's had loose stator retaining bolts also when they checked their WR450F's. My local dealer confirmed that I was not alone with this fault & they said that Yamaha knew about it but would not accept this as a design fault. The remedy is to use longer stud bolts, loctite them & turn the heads over (pancake the screwed end) to avoid them slackening off.My bike cost £600 parts & £400 labour to rectify. I am currently trying to get Yamaha to acknowledge them blame for this & cough up for the repair. If you know of this problem, please e mail me.

this should be a red flag to all 03 owners. it is one of several problems inside of the housing of the left side of the wrs engine. sorry to hear about your mis fortune too, and others. also in the line of engineering short falls under the cover besides rotor nut tourqe/falling off are the bolts from rotor to starter clutch gear, these will loosen up as well fall out and some will shear. yamaha so says im the only one with this problem and will not help, but two days ago i found a fellow that this happend to earlyer in the year. seems to me they need to take note of on going glitches and send owners updates on maintanace that needs to be added to the schedule. i personaly own a few yamaha bikes and have had lot of early yzs but from here on you would be hard pressed to sell me one after what i have seen on tt. ride hard,live to ride, good luck to you and your mates. :thumbsup:

I never had a problem with those bolts myself. The second time I fixed my woodruff key problem, I looked up all the parts in that area to find any superseced numbers. Those bolts, and a few other parts in that area, have a different part number than they origionally did. I ordered all the parts with new numbers and installed them at the same time as the repair. I haven't had any problems of any kind since then with the bike. I haven't updated my bike to the 04 starter parts and don't plan on it unless it fails again.

Yamaha (and other manufactuerers) does this a lot. They will update parts whenever they find a potential weak point and issue a new part number. If you try to order the old part number you will automatically get the updated part with the new part number. That is how they keep the faulty parts from getting back into circulation. The down side is the origional questionable parts are left in service on the bikes until they fail. Only if there is a risk of personal injury or death (or really bad publicity) will the manufacturers issue a recall. If people were getting hurt on their 03 WR's, instead of just inconviencenced, there would have definately been a recall to update the woodruff/starter clutch parts. As it is, I'm glad they did at least cover the woodruff repair (twice) on my bike. Just my .02

great point about the failed numbers, but does the starter number on 03 verses 04 the same? i hear tell the 04 starter drive has some tine of tourque limiter/ were as if the engine kicks back while starting it will absorb the shock in stead of the bolts in the one way clutch gear. live long mopar! rat motor head here! :thumbsup:

What bolts are you guys talking about exactly??

Part numbers would be handy if you got them. On yamaha's website, you can look up the part numbers on there part's drawings. Click the link below, then select "Parts & Service" and then the "Parts Catalog".


I belive that originaly first topic here was the stator retaing bolts came lose. slacked off. something on that order. it at lest would be a good idea to pull the left cover off every couple of rides and check all bolts, nuts for for proper torque. this should included the bolts into the starter clutch drive gear. it could be possible the harmonics these motors make while twisted up { all most on the engine speed limiter ] might shake bolts and nuts


I think the dealer forgot to use Loctite! If you had a dealer perform the TSB woodruff key service the mechanic may have forgot to use Loctite. I use red and blue everywhere in the engine. :thumbsup:

maybe the mechanic did use loctite on the rotor nut and crank, we are talking stator bolts come out here. what motive did he have to pull out other bolts on the left side as starter clutch gear bolts or stator bolts / loctite and re tourque. thats why i am here on tt. bolts fell out inside my motor while racing. where is GYRT ? :thumbsup:

where is GYRT ? :thumbsup:

Never heard of GYRT, but if you talking about GYT-R, it is a company that designs and produces aftermarket parts for Yamaha. For Example: a GYT-R muffler insert, GYT-R guards, and skidplates. The only place that I know that you can buy GYT-R products is through your Yamaha dealer.


Well i am from norway, and i bought a jused wr-03. On my 10-11 trip, my bolts that hold the starter clutch loosen up and cut off. I had to buy a new flywheel, stator and starter clutch. My org bolt was 13mm, replaced with 16mm the parts cost 590$, in norway. Earlier owner(son of a Yamaha dealer) said that i was very unlucky, [@#$%&*!]!! The father could not get me the parts for his own cost.. crap. I told about the woodruff key problems that i read about on this forum, and they ment that it is`nt a problem!!!

Sorry for my bad english

loctite is my friend

this reply is for the last two post first one sorry i got the tand r missed placed. this is suppose to stand for genuine yamaha tech - racing , rite now the way my bike sets with parts from the stator and bolts in two baggies, they would hate for me to show up at a national race event with my bike and play show and tell. i want to know where the clown is that runs that circus called .... yamaha motor corp.? to the last post the fellow from norway , i feel your pain, how long ago did yours munch down on the stator?

and did you try to warranty it threw your dealer? :thumbsup:

It broke 3 weeks ago, i bught it 4/4-04. I only asked about warranty to the dealer Where it was sold in the first place, but i wanted the bike up and running, so i paid for the parts and did it my self. I have read here in the forum, so i didnt bother trying so hard.. My problem now is that i think i hear everthing downthere when i ride, that kill a joy of ride. Just waiting for it to happend again, lol!!

Does anyone have the current part numbers for these bolts? :thumbsup:

this reply is for who wants to fix his bike maybe. hansiboy the dealers say there isnt a problem like yours and others of us but we/i know better. you did the right thing in my mind by replacing to larger size/ this could help and that would be my suggestion on those particular bolts. plus you could tighten the crap out of them also. these should be fine , maybe every ride or so just check em. this topic post is actually on the stator bolts backing off, read the entry post carefully. also check rotor nut , and it might be a good idea to up grade the starter drive to 04 part too.how about jetting? if stock fatten it up and get the zip ty screw. you dont want the backfire/kickback situation. it not the 03s freind. as for the noise or noises might try riding with ear plugs. not really better check more on tt, seen a post on problems on the right side motor as well, better safe than sorry. to dialoge maybe yamaha doesnt have a part number on the larger 16mm bolts you might have to hunt them and get at least grade 8. its a shame that you can spend what these bike cost and have to re-enginer them to make them reliable. that could be a under statement. :thumbsup:

its a shame that you can spend what these bike cost and have to re-enginer them to make them reliable. that could be a under statement. :devil:


Your situation is a very rare occurance. There are far more of these bikes out there that have never had a problem (woodruff key or anything else) than have. The woodruff key was the most common failure with these bikes and it still is only a small percentage that has failed. I had a loose primary gear nut on my bike. But with over 3000 miles on it that has been the only problem. I would call that very reliable. The problem with the bolts backing off in the flywheel is probably a case of incorrect assembly at the factory. When you manufacture something in the kind of numbers that the WR 450 was produced you are going to have a small amount of "scrap". Yamaha was unwilling to do anything about the woodruff key issue so I doubt they are going to even think twice about an even rarer problem.

Just fix it and ride it. :thumbsup:


lowedog youve been lucky and i hope others out there have the same luck as you. as for a few of us, at least me i will think twice be fore purchasing a new blue bike. how do i fix my bike? do you disasemble the entire engine and clean out the fillings from the stator/and bolts , or just put in new stator and related bolts? this is not the only yamaha i own nor the only motor cycle. its just one i my hairem thats sick. :thumbsup::devil:

lowedog youve been lucky and i hope others out there have the same luck as you. as for a few of us, at least me i will think twice be fore purchasing a new blue bike. how do i fix my bike? do you disasemble the entire engine and clean out the fillings from the stator/and bolts , or just put in new stator and related bolts? this is not the only yamaha i own nor the only motor cycle. its just one i my hairem thats sick. :thumbsup::devil:

I don't think luck has anything to do with it. All the other brands have had their share of problems too. Want to go red? Be prepared to replace valves once a year on the CRF.

As far as fixing it, I would replace the broken parts and change the oil a few times with some cheap stuff by just starting it and letting it idle. This should flush the motor out pretty good. A magnetic drain plug would be a good idea.

Then I would ride that sucker and not think twice about it. :awww:

Good luck,


This stator fualt post is a good post origanaly. If you are seeking knownledge on the wr. I will go get a rotor puller and start trying to fix my bike. I was going to open up the center hole bore&stoke it but i am still thinking about it. My love for this bike has grown cold. As the president of a big bore club i currently ride/race a kx5oo with some mods. Ride red? these are good too. {just some dont like to start up when the flag falls at the sarting line} I am thinking ride orange, they come race ready straight out of the box. Unlike blue came. Huh start life at 525cc and goes up from there/with the magic button/without flywheel,stator,starter issues. Maybe it has other problems, i dont know. HAVENT FOUND OUT YET.

other bikes 99 kx 500 tricked litely 00 indian chief bobber 00 96 inch turbo-charged pro street custom 00 klr 650 black color, flaming super trapp 75 suzuki gt 750 water-buffalo :thumbsup: others include 78 yz 400 evo racer/winner, new member of family 70 yamaha dt 250 all orig. Peace !

hey guys is anyone here able to tell me what size bolts and length they are so i can go replace mine with grade 8 if not grade 10 bolts from work.

Can anyone post a pic of what happens as i am a bad reader and it doesnt go through to my head what it is that breaks lol

I just read that should replace the bolts ????

so i can get bolts from work and loctite so i can do this before it happens.

Thanks guys if you could help out it would be greatly appreciated.

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