Preliminary data on woodruff key failures

After shearing 2 keys I decided to remove the 1st idler gear and run with the kickstarter only. (This was 8 months ago) The wr450 threads on off-road.com looked interesting so I dijested as many emails on the woodruff key problem as possible. Here is my conclusion. The 1st idler gear (closest to the starter) is supposed to spin at appx 34 ft-lbs. The new replacement is supposed to spin at 26 ft-lbs. I tested mine using a vice, wood and a torque wrench. The initial torque to move this the first time was about 85 ft-lbs. I presume it was siezed form the factory! Repeated tests after the initial were appx. 28 ft-lbs. Soon this will be reinstalled and tested ... I get back with the results. :):D

Here is my conclusion. The 1st idler gear (closest to the starter) is supposed to spin at appx 34 ft-lbs. The new replacement is supposed to spin at 26 ft-lbs. I tested mine using a vice, wood and a torque wrench. The initial torque to move this the first time was about 85 ft-lbs. I presume it was siezed form the factory! Repeated tests after the initial were appx. 28 ft-lbs. Soon this will be reinstalled and tested ... I get back with the results. :):D

Can you go into detail on the movement. So you are saying the second gear can turn backwards?

I think it is a compression fit and does turn both ways.

So the torque needed to turn gear backwards is higher than the torque holding the flywheel gear tight, thus, the weakest link is the flywheel twisting and breaking the woodruff key when backfiring, rolling backwards down a hill in gear, ect...

Yamaha Canada is treating me right. After riding the bike most of the season (though not as much as I would have liked) I had the dreaded sheared key. I had to push out of the woods and had my heart rate monitor sound the alarm a few times :) At 50 years old i'm not allowed to have too much fun.

Since my dealer is close by to my main riding area I took the bike over and we pulled the cover off to confirm our diagnosis. Since we had done the lapping deal during pre-delivery my dealer called Yamaha Canada and was told that Yamaha would supply the 04 crankset, rotor and idler gear under warranty. The bike was in the shop for a week and i'm back in the saddle again. :D

What is different on the 04 crankset, rotor and idler gear?

:)

The taper angle for both the crank and rotor have been changed for 2004. The idler gear is supposed to have a built in clutch that will allow it to freewheel in a backfire situation.

I was planning to buy a new 2003 WR450 in the Spring but I'd have to say I've changed my mind after reading about the woodruff key issue and especially the seeming lack of support from Yamaha. I'm in Canada, and I assume the Canadian models are affected as well. How about the WR250?

Good luck guys. :)

why would a my bike be problem free ? so far 800 miles,what would have been done different ?

i posted this on another thread but thought this would be a good place also. i removed idler gear1 to replace it with the new and improved one. i discovered that the small area of the side cover that suports the end of the idler gear2 shaft was broken. with the flywheel tight and the old idler gear1 not able to slip, something had to give. if this had gone undiscovered the center case could have been damaged and who knows what else. i'm posting this as a warning. i had no problems with the starter. i only found this by chance. it will take five minutes to check. my dealer is supposed to contact yamaha. anyones else have this problem?

why would a my bike be problem free ? so far 800 miles,what would have been done different ?

The majority of bikes don't have a problem. Sounds like the causes are varied, a locking idler gear, bad machine match on crank and rotor. Some even talked about finding their rotor nut loose coming from the factory. The tolarances are close enough that if one of these other problems present it self there will be a failure. But it happens to much and should be a concern for all of us that own these bikes.

FWIW my 03 has around 8 races on it and well over 2000 miles with no problems.

I had a problem with mine at about 20 miles. All that happened was the rotor nut backed off. Do you think this caused any damage to the rotor or crank?

mtrablue,

My bike is in the shop, torn apart for the second time, with a sheared key. I am trying to figure out what parts to order. I want to update all of the parts, like the "torque limiter" and cover. Yamaha is telling me that they don't have part numbers yet for the 2004 model. I realize that the Idler Gear #1 has been superceded by

5TJ-15512-01-00, but Yamaha doesn't know if it is the same as the "torque limiter" on the 2004. It also appears that the "cover" needs to be replaced, but I don't have a part number for it. Has anyone done the complete update yet?

Jeff

jeff

i've been trying to follow the thread about '04 starter updates to figure out the next step. i got the updated idler gear 1 and compared it to my old gear 1. damned if the old one didn't slip easier than the updated one. sixty bucks wasted. i guess the '04 torque limiter may be the only real fix.

when i pulled out the old gear i found that the side cover was broken where idler gear 2 is supported. (see the "wr450 may wanna check this" thread) even if my dealer is able to get me a new side cover i'll be kick starting till the '04 stuff is available. the dealers hands are tied, the solution to this mess needs to come from yamaha. i guess we need to cover their desks with letters from owners with all these problems.

alan

Hey Alan,

I saw your post with pics of the side case - that sucks. I agree that we need to be contacting Yamaha with letters and phone calls. If they don't know how bad this problem is, then they will never take us seriously. I am going to do both today, and I hope that everyone else will also.

Jeff

Take your bike to the dealer from which you bought it. Tell him you will give him $500 and the 03 for a new 04. Raise hell till he gives in.... make a scene in the store if you must, and come back frequently. :):D

you say that you took your air snorkel out. Did you have to re-jet it? I did the other 2 mods, gray wire and the throttle stop. Would it make any difference by taking the snorkel out?

Yes it make a difference. Pull that snorkel out! It helps the motor breath. The stock jetting is way too lean, so you need to rejet regardless of the snorkel. Enjoy!

Jeff

Re-jet is a must. I didn't completely remove the snorkel but rather cut the bottom out and shaped the top to act as an air scoop, but for now just pull it out and re-jet... I have been extremely pleased with my jet settings and never stall or stutter... The engine is perfect on this bike I just wish I could get the handling right for tight woods. I am going to try a 20 inch front.

Hi All! I am torn between buying the 04' WR or YZ, forgive me, I have not read all the posts but has Yamaha resolved the key,starter issue for the 04's? Does anyone have opinion they would like to throw out on WR vs. YZ?

Thanks,

KW

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now