woodruff key lead to cracked case?

24 replies to this topic
  • actonkarate

Posted December 06, 2003 - 04:25 PM


my case on my 03 wr 450 was cracked due to the kick back on the kick starter. Would this have any thing to do with the woodruff key?

  • drzphatkid

Posted December 06, 2003 - 06:55 PM


I think that i might have the same problem!! I have been having problems with my starter so i started to take off the left side case cover i noticed a crack where the idler gear shaft fits in to the cover...This would explain my starter problems .The gear won't always engage . :)

  • snapdad

Posted December 07, 2003 - 12:21 AM


If the woodruff key were sheared allowing the timing to advance or retard the resulting mis-fire could damage to your case. The e-start and kick start are independent of each other but but if your engine fires out of time the violent back-lash can damage both systems.

  • GrahamO

Posted December 07, 2003 - 01:13 AM


What if the key (and associated parts) withstands the force that usually causes it to shear? Some gears are supported by jounals in the case, correct? Couldn't that same force on those gears crack the case if the key withstands it?

Just a thought...

For those of you with the cracked cases, are your keys sheared? If not then the timing is on spot and couldn't be creating problems.

  • endurodog

Posted December 07, 2003 - 08:13 AM


Technically it's not the woodruff key thats the problem, its just a result of the problem. The problem is that when the bike back fires, or the engine kicks back, the starter on the 03 doesn't freewheel so the forces are transfered to the starter parts.

Most people that have a problem with this end up with a sheared woodruff key. I have seen a few post that looks like the starter gears have let go and these problems have shown up in not being able to use the E start or a cracked case (actually side cover I think but not sure).

This is just my opinion on the stuff I have read here. Hopefully someone that has cracked a case can fill in the holes in my story.

  • snapdad

Posted December 07, 2003 - 08:25 AM


that's true for the left side, (starter gear, starter idler gear and one way clutch gear). but on the right side the kickstart gear system (kickstart gear, idler gear and kickstart driven gear) are all connected to the primary gear on the right side of the crank so even if the woodruff key were sheared on the rotor side any force from a "kickback" would travel through the gears on the clutch side.


Posted December 07, 2003 - 08:38 AM


Endurodog, IMO you're exactly right about the woodruff problem. If I had an '03 I'm not sure I would want the key loctited. Hmm... $2 key vs $80 case cover (or gears, starter motor, etc). Yamaha really screwed the pooch on this one. I would hope they would step up and make it right but I doubt they will. If this were a street bike you can be sure they would. As far as cracking the cover I'm sure it's possible on the left side but I think the kickstarter housing is a different issue.

  • endurodog

Posted December 07, 2003 - 09:43 AM


Yamaha really screwed the pooch on this one. I would hope they would step up and make it right but I doubt they will

I havn't had a problem yet (knock on wood) and the $350 for parts sucks. I think at a min. Yamaha should offer a update kit for right around $120. To be totally right they should fix the problem though.

  • Indy_WR450

Posted December 07, 2003 - 05:27 PM


I think it is only a matter of time before we all get the failure in one form or another. I have not touched my woodruf key so I hope it fails before something more expensive breaks. I have orderd the parts and will upgrade as soon as possible. I wonder if we can get all the WR450 owners to submit one collective request to Yamaha with all of our signatures, names and addresses. We may have leverage as a group. Do we know how many 03 WR450 owners are on our forum and the percentage of failures ( I think we had a pole on this earlier). :)

  • mtrablue

Posted December 07, 2003 - 08:43 PM


is there such thing as an e-petition? i sent them a letter three weeks ago, haven't heard a thing. i figured i'd get some sort of form letter buy now. not sure what it will take to shake 'em up.

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  • GrahamO

Posted December 08, 2003 - 08:57 AM


One of my clients is across the street from their Cypress office. Perhaps a one man demonstration would do the trick?

  • timvv51

Posted December 08, 2003 - 09:05 AM


Is this case cracking syndrome still possible if you remove the idler gear and disable the starter alltogether? I seems I read one post and saw pictures of a cracked case on the kick starter side. Thats the one that bothers me the most.

  • Gadsen

Posted December 08, 2003 - 09:32 AM


Is this case cracking syndrome still possible if you remove the idler gear and disable the starter alltogether? I seems I read one post and saw pictures of a cracked case on the kick starter side. Thats the one that bothers me the most.

Tim, I have a freind with a YZ450 and twice, he had it in the dealership for kickstarter repairs. He didnt elaborate, but the first was just out of warranty by a few days, Yamaha did fix it. Well, it happened again, they fixed it, but there was something in the case he said was broken in the kickstarter area, not sure, but I'd be willing to bet he had a sheared key both times, and they repaired the key the last time in. He complained it would pop back too. Now this was a YZ, so it never had the electric start.


Posted December 08, 2003 - 11:39 AM


Actually the problem with the kickstarter on YZ's is they break off the kickstarter stop in the case. Never heard of a YZ shearing the woodruff key. Doubt it would.

  • drzphatkid

Posted December 08, 2003 - 06:08 PM


Oh You mean this one!! Posted Image

Or was it this one ??? because i have both and now the crack in the case cover!!!! Posted Image

  • timvv51

Posted December 08, 2003 - 07:14 PM


Yup. Thats the one. Did you say that was after a backfire with the electric start or a kick start? Tim

  • drzphatkid

Posted December 08, 2003 - 08:30 PM


Kick start!Going to the yamaha dealer about the crack in the left case cover tuesday,hopfully it will be covered or atleast a goodwill fixx.The mecanic said that he might get yamaha to fix it for free. :)

  • dossyboy

Posted December 09, 2003 - 01:44 AM


oh dear! ive had the cover crack on me but that looks damn serious, is that the actual crank case as opposed to the cover?. my bike was bought from an unoficial importer so yamaha wont even put me through to the complaints dept! count me in on that petition though! wheres my nearest honda dealer?

  • timvv51

Posted December 09, 2003 - 10:44 AM


I'm still hoping that pulling the idler gear stops the problem with kickbacks and cracked cases. Timvv

  • Indy_WR450

Posted December 09, 2003 - 09:57 PM


I think you are right Timvv51. If you remove the connection to the e-start drive train you can kick start the bike only and you wont run the risk of cracking the case like above. But I hear that the kick starter design needs another bearing to support the arm connection. There were several posts on this on the YZ450 forum earlier this year. I think the 04 WR450 starter redesign retro fit is the best solution even though it is expensive. I wonder if Yamaha redesigned the kick starter bearings in the 04 model. :)


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