Rotor lapped and torqued still shears key

I heard he has sheared a sheep but not a woodruft key :)

Sputter, The thread "Preliminary data on Woodruff key failures" is susposed to find if there was a certain range of bikes with failures. At first it looked as though all failures were in the above 1000 sn. That has dramatically changed in the last 2 weeks with failures occuring in all serial number ranges. Thats bad news, as it now looks like a design flaw and not a production failure. Please report your failures on that thread.

dramatically changed

Alabama what are the numbers that say "dramatically"?? How many outside of that range have failed???? I don't believe it is dramatic.

Ok I'm editing this, I went back and checked for failures that have been posted about here outside of the 1000-1999 number range. I have found 3 for sure and 1 possible.

0996 for rainman in the orginal post

0389

0947

some one listed this 58X, don't know if this is it.

Now maybe the orginal range should be adjusted to the 947 range and then there is only 1 for sure and 1 maybe out of that.

I don't think the use of statements like "dramatically" help people make informed opinions about this issue.

I have serial number 1045 and I checked my rotor nut with a torque wrench and could not tighten it with the wrench set at 60 lbs (higher than 47 lbs spec). I had the bike in gear with the rear sprocket locked from turning against the swing arm. I have yet to have a backfire. I hope this problem is not due to an overly heavy flywheel for the crank shaft diameter. If this keeps happening to WR450s we may have to take some weight off of our flywheels to prevent shearing 30 miles into a trail ride. I have less than 40 miles on the bike due to the heavy winter we are having. I am concerned and hope the forum members manage to get to the bottom of this issue.

some one listed this 58X, don't know if this is it.

I don't like posting specifics on the internet. Mine is "five-eighty-something", which places it between 580 and 589. Close enough for statistical analisys.

I don't believe it is dramatic.

Mine's broke. Dramatic enough.

Mine's broke. Dramatic enough

I'm sure it is for you but not in a statistcal sense, or in the sense as Alabama stated "Dramatical changed in the last 2 weeks". I found yours quite aways back in my search, is it over 2 weeks ago that it broke?

As far as the "dramatic" in the original form I addressed in in, no it's not dramatic. Were trying to get to the bottom of this and words like dramatic increase when there isn't doesn't help. I am considering one of these bikes and when I read the thread it doesn't give me good information when people are using all the drama to describe the situation. While I'm sorry your having trouble with your bike and appreciate your input into the forum, the fact remains that most of the failures have happened in range of vin numbers with a few out side of that. There has been no dramatic increase in the last 2 weeks or failures outside of the original data, an increase yes, dramatic no.

I just returned from riding 75 miles at Foresthill, CA with no problems. I had lapped the rotor when I assembled it. Years ago I used to change the timing on my engines by removing the key and indexing the rotor to where I wanted. The key is only for proper timing alignment. The taper fit is what should prevent the rotor from changing position.

I lapped my rotor about 20 times to get a good fit where it required some effort to pull the rotor back off after tapping it on with my hands. I suggest lapping it again.

FYI, Yamahas Raptor 650 Quads are also capable of shearing woodroof keys. These engines have a lot of flywheel weight.

Also # 413, 580, 996,389,947... And most people who have bought new bikes and had failures do not log into Thumper Talk! This is a great handling machine with the best 450cc four-stroke on the market. I have 145 miles on mine and luv to ride it. My times on test trails are way down...BUT, there is a big cloud over our heads that only Yamaha can clear out! Yamaha owes us an answer. What's dramatic? Try being 15 miles from the truck at dark with a broken down bike. Thats dramatic.....

413, 580, 996,389,947... And most people who have bought new bikes and had failures do not log into Thumper Talk!

Again 5 outside the range does not make a "Dramatic increase over the last 2 weeks" as you stated in your one post. Of these 5 not all were over the last 2 weeks, the prelim data on this was not total, it was one person doing some hard, well thought out, work. Now we have more data and your expand the Vin numbers by 155 and you have 3 failures out of the range.

Actually if you look at the number of people that own these bikes "Most people" have not had a failure. Alabama I would love to see your research to support your "most people" theory. Look back at the research that was done on this site, most have not had a problem, far to many yes, but most, no.

What's dramatic? Try being 15 miles from the truck at dark with a broken down bike. Thats dramatic.....

Yep if you make it dramatic it sure can be. To some its burning the toast Or is dramatic being in the Afgan country side with bullets wizzing over your head. It's all a matter of how you measure dramatic or is it the way some people are approaching this problem??

Seeing in another thread Yamaha is trying a fix so hopefully this will end all the "dramatic" statements and a real solution will be found.

Post deleted by Wrench

What other than dirtbikes and skateboards where the consumer does more work than the factories to get the thing right? Rock on :) it's worth it.

5 miles into yesterday's ride, sheared key # 2. This after Yamaha replaced original sheared key and torqued to 47 lbs. Dealer contacted Yam Tech twice on this and stated torque was the problem and it shouldn't reoccur. Crossed a mud hole and it died right in the middle - of course. If they don't fix it properly this time, I'm giving it back. I've been towed out of the woods the last 2 times out - not pretty! Never been let down by my XR! :)

The key is only for proper timing alignment. The taper fit is what should prevent the rotor from changing position.

Exactly.

Just replacing the key and "re-torquing" is not going to fix this IMO.

When one considers how important the fit is with this taper, the taper is doing the job of holding this rotor - the key is there only to locate the rotor. When a key is sheared it moves metal around both parts, both in the critical area of the keyway. If there is a 10% reduction in contact area between these parts after shearing the key the ability to hold is greatly reduced. If the keyway has .010 slop in it now, (and it is going to be at least that), how is that going to affect timing?

Yamaha needs to step to the plate and replace these parts if the key sheared. There is no way to fix this as good as new, why accept anything less?

I believe this WR450 market group is very important to Yamaha. They understand who has discretionary income and what they buy - the last thing they want to do is alienate this group.

If I owned a WR450 my dealer would be very tired of me - then I would be on the phone to the local Yamaha rep and he would know how I feel. If 100 of you did this things would happen.

"When a key is sheared it moves metal around both parts, both in the critical area of the keyway. If there is a 10% reduction in contact area between these parts after shearing the key the ability to hold is greatly reduced. If the keyway has .010 slop in it now, (and it is going to be at least that), how is that going to affect timing?"

Sounds like there is no way to fix it after it shears the key. Replacing the crank is the only way to put it back to 100%. :)

Replace the crank and rotor. The crank is going to include the rod. That means the greasy fingered kid at the dealer will be splitting the cases, pulling the pin from your piston :) and putting it on the new rod to put back together in your motor that is scattered all over his bench along with the donuts left over from Fat Tuesday, (how much did this bike cost?)

I believe this WR450 market group is very important to Yamaha. They understand who has discretionary income and what they buy - the last thing they want to do is alienate this group

Yamaha didn't think much of the quad owners (Raptor 660R) after they spent $7k. Blown trannies and blown starters with Yamaha's response being "rider error". One poor guy blew through FIVE "one way bearings" in the starter. That's alot of "rider error"!

They must be sweet machines if we take this kind of treatment (I had a Raptor) and keep coming back for more.

Just a curious question---do you use the electric start a lot? The reason I asked is that all of the torque from the electric starter goes thru the woodruff key? Is this making the key break???

OK Enduro, its only a 35% failure rate in the first 2 months of ownership. Hey, that's pretty good! :) I think Dutch has got it right.

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