Preliminary data on woodruff key failures

I've been told by a couple machinist/mechanic guys, if the woodruff key shears, it does irreversable damage to the crank. Aint no lappin compound gonna fix it...

A new crank is the only 100% fix. :)

finally recieved the 450, rode it hard for 20 miles, sort of? no problems either. e-start everytime. i think its # 2405 if the last 4 digits on the serial # are the right numbers? dont know if the torqued it to 47lbs at the shop, but the manual did have a loose page saying to torque to 47lbs, then re-torque to the same, but the manual was sealed? jetted to 6,000-7,000 feet and they removed the baffle at the shop, thye put race fuel in it too, runs awsome!!!!!!!!!!



whoa calm down Xr.I had 1 key break and have over 300 miles on it now.I think the first one wouldn't have broken if i checked the torque after 50 miles or so.Since the first sheared i have only used the e-start trying to shear another key.No failures yet. :)

I have watched this pretty close. Over the last 2 weeks I have read about no new failures, either from the guys with bikes sitting at home or the guys riding them. I'm spose to pick one up in the next few weeks and I'm feeling much better about it now. Hope the guys I race against leave theirs sitting at home.

Damn just saw that some did. shoot

<ul type="square"> "The total now is 120 miles and three woodruff keys."

Bring the WR back to your dealer and tell him you want him to replace it with a new bike. When he says no, have your lawyer call him, and Yamaha.

I'm a "soon to be" taking delivery WR250F owner. I went with the 250 because I heard about this problem being 450 only. What Bean mentioned is what I heard from the dealer about the 450 problem after I ordered a 250. I also was told that it was a "not warming it up" problem. Basically he was implying that kick should be used to start the bike when cold or you get this:


if there is a backfire and the starter mechanism locks the flywheel and the piston still wants to turn the crank, it looks like the key may be failing because the crank is slipping but the flywheel is locked in place because of the starting mechanism

This is what I gathered from the dealer. I think they are masking an all out design flaw, but this could be a "not reading the manual situation brought on by new owner excitement.

Sheared the key after 120 miles -- simply starting it with the electric start sitting in the driveway. The bike is no. 1314. My mechanic's (i.e., my brother's) guess is that it was ready for the 15 hr service (I was right at that -- maybe a little over) and the rotor nut had backed off enough to shear it. As previous posters have noted, the manual recommends checking the torque at this time.

Since my dealer claims not to know about any broad issue (tho I have not spoken with his Yamaha mechanic yet), I am trying to get the name of the Yamaha rep in the area to see what they say.

Don't know if you guys have seen this for what it's worth:

Hi SBG!Where in Ma. are you from? Where do you ride? I just got the WR450F on 2/3/03 but still not seen the dirt, only snow.I have to bring my bike to the dealer tomorrow so they can remove the flywheel & lap the crank and retorque.It's about time to see 50+ weather in the forcast.If the snow is gone next weakend,me & my son will be heading to Wrentham or Brockton.Well, maybe we'll see you and your 250 on the trails.See Ya! :)

03 WR450F-grey wire mod.,Pro Taper bars,Works connection frame guards,Carbon fiber front & rear disc guards and rear caliper guard. :D

Out east of California City in the Mojave desert for the second time on the new 450. Did a 90-mile loop Friday. Saturday's loop ended for me about half a mile from camp. Stalled and backfired at low rpms, & coasted down a hill. The e-start spins the rotor, but not the crank. The k-start spins the crank, but not the rotor & no spark. I guess I'm a statistic now, huh?

Serial # 1234, Re-torqued at 90 miles, FAILED at 457 miles.

Catfish ...

I'm from Rehoboth on the Providence RI border. I haven't ridden in a long time nor do I actually know of a riding area, but some guy I work with was mentioning having a WR250, so I decided to get a new bike after 13 years. It still isn't in yet, so I'm ordering all the accessories while I wait. Weather was real nice this weekend. Up to 65 degrees out my way. When the weather gets better and I actually get my bike in, I'll have to meet you at one of these riding areas. Later!


That sounds like a great idea!Freetown is the 1/2 way point but will have to wait to May to go there.There are more areas up this way to ride before that.Thought I would get my bike back today but it looks more like Fri.Keep in touch ok.

wr450 one week old. 7 miles on the odometer. pin failed on the first ride. frame num 0598. Calling customer assitance.

After paying for mine today, that I will be picking up on Friday, I went to see the service manager. He was very aware of the problem from Yamaha and said they would retorque the rotor as part of the prep for delivery. He is usuall pretty talkative but wouldn't volunter any additional info. It it's going to break on anyones it will be on mine. Engine # 3173

Just wanted to let you know your information is very interesting. I'm glad you guys take the time to help others and I just wanted to add my stat. for the record. I have a 03 WR450, a little over a month old. 75 miles on it. I did remove the rotor nut and loctite it. I can't tell you about torque, I just bumped mine pretty good with a 1/2" air impact. No problems so far.Serial # 1035

Remember the "Throttle Is Your Friend"

IceBox et al,

I'm new to the forum - been lurking for a while. I have a brand new WR450F (USA Model) and the manual has no inserts, paste overs, stickers, etc.

According to this version of the manual, the correct torque for the rotor nut is 61 ft-lbs (not 47, or 50). This is on page 4-77 of the manual.

Due to weather I have only ridden the bike briefly. I have to admit I'm a little spooked. Methinks I had better have a talk with my service department and Yamaha.

I have the service manual that a fellow ThumperTalker provided awhile back. Mine says 50 ft-lbs but the difference between 47 and 50 could be a maladjusted torque wrench. I think one important thing to do at this point since there haven't been clear answers from Yamaha and the internet sometimes inflates problems (no flame intended TTers) is to make sure that the rotor nut is torqued, backed off and retorqued.

If you do a search for woodruff and/or key, you will find a ton of posts.

Welcome to ThumperTalk, you will find a lot of informative info and some entertainment too.

Since you have a US model, I would get any problems in writing with your dealer to avoid "he said" problems later on. 30 days isn't much time but better than the Canadian version 0 days :)


Thanks for the welcome. You're right about the entertainment value. The discussion on cam timings and horsepower was *very* entertaining.

Anyway, I did some phone work today. It took several tries but I finally found a local dealer who has had a WR450 come in with a sheared key. In this case, it was definitely a torque problem. According to the mechanic, the rotor came off with out even using a puller it was so loose.

I spoke to my dealer and while they had not heard about it they were more than willing to check the bike out and retorque the nut for me at no cost.

Here's hopin'

F.Y.I. There is an update sheet put into the manual that changed the data given on that page to 47 Ft.Lbs


I have noticed others have mentioned that but the dealer I spoke with said that has been revised. Whether that is true or not :) I will find out on Saturday.

I can't comment too much until I get a copy of what he was sent but the difference between 47-50 ft-lbs is really just a torque wrench that hasn't been calibrated lately since most have a +/- 3% margin of error to begin with. I find it interesting that at one time it might have been 61 ft-lbs and then dropped down to 47 ft-lbs with the insert you speak of.

Just my .02

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