'03 to '04 WR450 Starter Drive Update

As promised I took a look at an '03 WR450 left side cover today and compared it to my '04. The most obvious difference is that the idler gear cover on the '03 is flat and the '04 is raised a 1/4" or so. I didn't have time to make any critical measurements (all the other guys chomping to ride) but the actual engine covers look very similar if not the same. It looks like you might be able to install the 'torque limiter' by just changing the idler gear cover but I'm not sure. I hope this helps. I took some pics but I'm unfamiliar with how to post them here. Can anyone help with that?

email the photos to me at bibmen@bibmen.com and I will post them for you.


Here are the images.





Thanks alot guys, that looks interesting. It looks like a possible retro-fit.Is this a newer version yet of the idler gear update?

Wow, great photo's.

At a glance it sure looks like they might retro-fit '03s. :) Lets hope so.

You called it a 'torque limiter.'I take it the gears did not spin freely of each other in either direction? Just curious. If it's a clutch of some kind, it might lighten the flywheel effect of having to turn that big gear and starter. :D

Anyway, thanks for the pic's. I think I'll hold off installing the updated gear I just bought.

The part is identified in the manual as a 'Torque Limiter'. I believe it's designed to slip above a specified torque thereby protecting the starter and the infamous woodruff key. I haven't ridden an '03 so I can't compare braking but I don't think it will have any effect on that. I think it only comes into play in the event of a kickback during starting. I'm going to try fitting in my friend's '03 later this week and will post an update as to whether it fits or not.

It sure looks as if we can retrofit the parts. I will order them as soon as somone confirms the fit and all the part numbers. Thanks for the great post. :)

Yamaha SA fitted those exact parts to a friends 03 after it failed 2 times.

I'm waiting for my parts to arrive so they can also be fitted. Yamaha is paying, not ME !

Craigw, tell us more about Yamaha paying for the 04 stuff, do you know what the parts are? and if your dealer is doing this out the the goodness of thier hearts or is the factory doing it?

Yamaha should provide FREE OF CHARGE these parts to every 03 owner who has a bike in the affected VIN number. That is the VERY LEAST they should do. IMO...

Yamaha should provide FREE OF CHARGE these parts to every 03 owner who has a bike in the affected VIN number. That is the VERY LEAST they should do. IMO...

I agree with you, but '03 owners are to lame and just accept that they are getting F**ked in the a-hole by Yamaha. I'm waiting to see if there are any problems with the '04 before I buy one, otherwise I'm going with red.

otherwise I'm going with red.

Red has their problems, too. Besides, WR450 and CRF450 are similar, but don't really fit the same applications. I agree though, we really need to hound Yamaha about this. Where does one start?

Perhaps we could start by finding out how CraigW got his parts from Yamaha... CraigW?

Craig is in South Africa. Y South Africa is obviously more concerned than Y USA. What '03 owners need to do is hit the dealerships and Y USA at the same time/week, demanding that the TT members are not going to back down till the issue is resolved for all that want the proper fix. :)

You called it a 'torque limiter.'I take it the gears did not spin freely of each other in either direction?

I think when they say "torque limiter", I bet they are reffering to some sort of cushion. I'll bet its sprung to absorb the brunt of a load, probably to keep the woodruff keys in place. My twin bro had an Ossa Stiletto 250 and it has a similar deal, it was called a "cush drive" and it was a spring loaded gear. A clutch disc also uses spring to cushion the load on a car/truck application. This is all just a guess, but it makes sense. :)

This is an example of a "torque limiter." It is not the exact TL used in the WR, but could be very similar. Looks to me like a clutch without the ability to manually disengage. Instead, when a certain torque is reached it will start to slip.

Example of a TL. Click here.

I suppose that someone other than Yamaha will have to make the retro fit part for the 03, they don't seem to be interested in fixing last years problems.. I would think that the woodruff key issue has been addressed effectively in the 04 with the larger crank and flywheel and the torque limiter.. I'm advised by my mechanic at the Yamaha shop that there is NO way the new part can be retrofitted to the 03. Maybe some after market outfit will clean the egg off of Yamaha's face.. :)

Big Jim, Are you sure it cannot be retrofitted? Do you trust your mechanic? I really want to do the update. My bike is torn apart in the shop, for the second time. I measured the cases on an '03 and '04 and they appear to be the same, except for the cover of the "torque limiter". Why won't it fit?


Jeff, NO I do not believe my mechanic, he's a great guy but Yamaha has continually fed him a bunch of Bullshit from the very start of this soap opera..Maybe there is a true mechanic on the forum or a person from Yamaha who can tell us.. There was NO change in the idler gear that slips a little easier, but they changed the part number so who knows?? I would really like to do it to because I like the e-start but I'm going to take the gear out in Baja because I can't afford to break down there.. :)

Hey Jim,

I just got back from my dealer and I told him to just put it back together, and leave the idler gear#1 off. I am going to just run it as a kick start bike until Yamaha comes clean with us.

Have fun in BAJA!


Okay, here's what I have found out. I took a look at my buddy's '03. There's good news and bad news. The good news is I believe the torque limiter is definitely retrofittable. The bad news is it will likely require 3 major parts. The crankcase cover is virtually identical in the'03 and '04. However the idler gear shaft on the '03 is 12mm in diameter and the shaft on the '04 torque limiter is 10mm. Yamaha has installed a bushing in the cover to reduce the diameter in the '04 cover. I believe the bushing also acts as a bearing for the torque limiter as it does not have a seperate needle bearing like the idler gear. So the bottom line is you will either have to replace the engine cover (~$98 I think) or come up with a bushing to install in the '03 cover. The other parts needed are the torque limiter itself and the torque limiter cover. There are also two thrust washers that appear to come with the torque limiter but not sure. All told about $200 retail for everything. I will email some more photo's to BIBMEN and see if he would be gracious enough to post them for me.

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