Had a BIG failure on my '03 WR450 today. Key?



24 replies to this topic
  • YZ426guy

Posted December 28, 2003 - 03:11 PM

#1

Any help would be appreciated. I stalled the bike in the woods. Hit the magic button and it seemed I got a lean backfire. Hit it again and "click click". I heard the starter bendix gear moving, that's it. The kick starter would not move at all. When put in gear and rocked, engine would not move at all.


I washed it and removed the left side cover. Removed the "starter gears" to completely isolate that from the crank. I removed the rotor nut (previous owner did the locktite mod). The rotor nut seemed to be at the correct torque when removed. When I look down where the woodruff key should be, it's hard to tell if it is there. I don't have a puller to remove the rotor (I'm going to try to borrow one from a dealership tomorrow).


The crank now turns, but does not "sound" how it should. I can kick the bike through the stroke (I'm doing this gently, as I fear further damage) and it feels totally wrong.


Tranny and clutch appear to work fine. In nuetral, the engine is correctly isolated from the engine.


Has anyone else had a failure like this? Is this just a simple woodruff key failure? Any help would be appreciated.

  • Indy_WR450

Posted December 28, 2003 - 03:43 PM

#2

Sounds like you need to get out the puller. Most likely need to have crank lapped and refit to the flywheel. Best advice is jetting to avoid future backfire. All that have been lucky with the woodruf key failure have had good jetting. It will happen again if you dont take care of your jetting. :D The O4 WR450 has a different starter mechanism. approx $400. upgrade. :D Or you can remove the e-start drive gear and just use the kick starter. Or you can watch your jetting and keep the e-start. :)

  • WR250fla

Posted December 28, 2003 - 03:44 PM

#3

Yes, that sounds like a possible key failure. I have had more than my share.

  • WR250fla

Posted December 28, 2003 - 03:56 PM

#4

Two of my woodruff key failures happened while turning the motor off,not one back fire or anything.My bike is jetted very well. The lack of the torque limiter looks to be the main problem for those of us that have had problems.Thinking jetting is the problem is llke thinking loctite will fix it.

  • SMD

Posted December 28, 2003 - 04:56 PM

#5

Sorry to hear....but you can bet its a chucked woody key. :)

  • gfergtr74

Posted December 28, 2003 - 05:17 PM

#6

Just curious on these keys. Is the failure due to weak material used to build the key? Would it be better to go to the local auto parts store and buy a key simmilar in shape and just shape it yourself? :)

  • Kot

Posted December 28, 2003 - 06:09 PM

#7

[QUOTE]
The crank now turns, but does not "sound" how it should. I can kick the bike through the stroke (I'm doing this gently, as I fear further damage) and it feels totally wrong.



Well, if your key is shreded, it simply means that your rotor would move against the shaft. Will effect your starting, The timing is not there anymore, however if you just move your kick starter, there will be no strange sounds due to the key problem.. :D

Not sure what's the actual problem with your bike, but even if the woodroof key started that problem, something else happened as a result. Again, key is there to align the rotor for proper timing, if it fails, the worse that can happen is that the broken key will drop down and cause the cover damage, but this will not anyhow create "totaly wrong sounds" when moving the kick start. However this is all just MY Opinion! I might be wrong! :)

  • Indy_WR450

Posted December 28, 2003 - 07:19 PM

#8

Sorry WR250FLA you are wrong big time! :) The starter gear assembly only breaks the woodruf key when the engine backfires or has back drive. Many of us on this forum (60% or more of the WR450's) have not had an issue! There has been a lot of discussion on this forum about this issue and this is the conclusion of the majority of our WR450 owners. :D

  • Eddie Sisneros

Posted December 28, 2003 - 07:25 PM

#9

the key doesnt hold any thing.its only purpose is for alignment.

  • endurodog

Posted December 28, 2003 - 07:31 PM

#10

Since your rotor still seems mounted securely to the shaft and the engine wouldn't even turn over, this sounds more like the failure was in the starter gears some where. All of the key failures I have heard about the bikes turn over just fine after the key shears with the E button or the kicker, they just won't start because of the timing being off. I would look at your starter and gears real close.

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  • mtrablue

Posted December 28, 2003 - 07:52 PM

#11

it is not uncommon for the motor to go "backwards" if shut off while the piston is in the middle of the compression stroke. the piston is pushed back the way it came and the sprag clutch is engaged. don't know if it's enough to break things.
check to see if the side cover is broken where the small idler gear is supported. a few of us have had the small half circle of material break. it is possible for it to get somewhere it shouldn't.

  • timvv51

Posted December 28, 2003 - 09:18 PM

#12

Jetting schmetting the motor ought to be able to take a little back fire without shearing the key but obviously some of them can't. It seems like if a little backfire will break the key eventually hard panic stops and stalling the motor and just the general hard use a dirt bike gets could shear the key if there is something else wrong like poor fit or not enough surface area designed into the fit. I had quite a few backfires or kickbacks before I changed my jetting and quit using the electric starter but it didn't shear the key. My bike was delivered in Febuary and was right in there with the serial numbers that were having problems so I dont get it why mine hung together. A friend bought a bike sitting right beside mine on the showroom and his sheared the first time out. Something weird is going on here. Tim

  • WR250fla

Posted December 29, 2003 - 07:21 AM

#13

I know how my woodruff keys have broken and I know what Yamaha has done to prevent it on the 2004 models. (Indy)Explain back drive and how it can happen just by hitting the kill button, regardless of jetting. The people with broken keys and or cases feel that just because 60% haven't had promblems so far, doesn't mean crap. There is a problem. I bet Yamaha has fixed the problem with the 04,and it wasn't by jetting the bike.

  • timvv51

Posted December 29, 2003 - 07:27 AM

#14

My sentiments exactly. Wish I knew why some shear and some dont so I would have a better idea whether mine is a ticking time bomb. Single track at 12000 feet is no fun if you are worried about a failure. I may go back to a BRP for reliability. Tim

  • pedman

Posted December 29, 2003 - 08:27 AM

#15

Sorry WR250FLA you are wrong big time! :D The starter gear assembly only breaks the woodruf key when the engine backfires or has back drive. Many of us on this forum (60% or more of the WR450's) have not had an issue! There has been a lot of discussion on this forum about this issue and this is the conclusion of the majority of our WR450 owners. :)


40% is not acceptable either :D Does anyone have an exact number of TT members that are having failures vs. not having problems?

  • endurodog

Posted December 29, 2003 - 09:09 AM

#16

Wish I knew why some shear and some dont so I would have a better idea whether mine is a ticking time bomb.



I will throw out my theory on it. I think its cause the tolerances are so close. Some bikes are just a bit out of tolerance and there for fail. Some are in and don't. It seems it's a much finer line than in other production motorcycles. Just my thoughts on it.

  • timvv51

Posted December 29, 2003 - 10:52 AM

#17

Good theory Endurodog but a scary one too. Does that mean when we get a sufficent number of miles on our bikes to get the thing loosened up ours are susceptable to failure also? I would really like to keep this bike and I suppose doing everything to eliminate backfires is the ticket. That and eliminate the idler gear. Tim

  • Indy_WR450

Posted December 29, 2003 - 11:04 AM

#18

Look we all agree that there is a design problem with the starter drive for the 03-WR450's. All I am saying is that a backfire may result in a broken key at best or a broken starter gear assembly at worst. All the failures to date have been related to backfiring or improper taper fit of flywheels. For us with thousands of miles and no failure, we need to avoid the dreaded backfire to avoid these failures. The design flaw has been recognized by everyone including Yamaha. Us 03 owners have a choice on how to deal with it. :)
1. Jetting and continue as is with fingers crossed.
2. remove starter drive train and eliminate the e-start and now deal with kick start bearing issues that the YZ450 guys deal with.
3. Upgrade to 04 design parts for approx. $400.00
I have ordered the 04 parts and will keep them until I have the famous failure. Meanwhile I am going to keep my jetting good and ride as much as I can. :D

  • endurodog

Posted December 29, 2003 - 11:20 AM

#19

Does that mean when we get a sufficent number of miles on our bikes to get the thing loosened up ours are susceptable to failure also?



Well in my theory yes and no. If the taper on the flywheel to crank shaft is with in tolerance that should not wear out because there is no wear on these parts, either it holds or it doesn't. Now the starter gear problem I think will eventually get us. There is constent wear on these parts everytime the bike stalls or back fires.

Now this is just my theory but the evidence seems to support it.

  • timvv51

Posted December 29, 2003 - 12:56 PM

#20

Hey Indy, I can cross my fingers and ride pretty good most of the time but its hard to cross my toes inside my Alpinestars. :) Tim




 
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