2003 WR450 starter problem information for a potential new owner

Can you guys let me know what the starter issue is for the 2003. i have a couple I am interested in but heard they had problems with the 2003. What does the fix entail and how much is the fix. Is there a way to know if there is a problem or if it is ready to blow? Thanks for the info!

The deal is that the starter motor just quits all together. The fix is to put an 04 starter on it and problem solved. Better check out the Woodruff Key on that rig as well. This is truely a time bomb and will end your day fast. Ask the sellers if they have done the mod to fix this, if not either walk away or discount the price to take care of this ASAP.

Here is a list of parts, as well as a great price to upgrade the 2003 WR450F starter system to the 2004 configuration.

Look up <http://www.zanottimotor.com>

The price for the update to your starter system, if ordered through them, is less than $170 + shipping. Order the following parts from them:

5TJ-15560-00-00 - Washer - 1 @ $140.20 (This is the Idler Gear Assy/

Torque Limiter)

5TJ-1549B-00-00 - Torque Limiter Cover - 1 @ $19.80 (includes O-ring)

90201-105A8-00 - Thrust Washers - 2 @ $4.96

90380-10002-00 - Bushing - 1 @ $0.54

An alternative is to use this list and prices to negotiate with your local Yamaha dealer.

The fix takes 10 minutes. Look at page 4-78 in your 2003 WR450F Yamaha Owner's Service Manual for a visual on the parts involved. Take off the Idler Gear Cover and discard. Remove Idler Gear Assy and discard. Press the Bushing into the small hole in side case, where the Idler Gear was removed, with a hammer handle or similar soft object. Install one Thrust Washer on either side of new Idler Gear Assy. Insert new Idler Gear Assy in newly installed Bushing in side case. Install gasket (it's an Oring) from the old Idler Gear Cover or use new one on to the new Torque Limiter Cover. Install the Torque Limiter Cover using the old bolts. Done---go ride it.

Thanks for the info but what do you mean by the Woodruff key as well?

Here is the short version of the 2003 WR450F Woodruff Key/Starter Motor problem. The owners of the first 2003 bikes delivered, almost immediately experienced problems with the flywheel spinning when starting the motorcycle with the electric starter. When the flywheel spun, the woodruff key would shear. The bike could not be started after that. Many people reported long walks back to their trucks pushing their motorcycles. Mine sheared in the garage. Yamaha came out with a fix, which was to lap the flywheel and crank, loctite the flywheel and the nut onto the end of the crank shaft and torque the flywheel nut to a higher value. Almost immediately, reports came back of sheared starter motor output gears and cracked side cases where the starter motor was installed. By this time, the cause of the problem had been determined. The idler gear between the starter motor output gear and the starter clutch ring under the flywheel was a pressed together assy of two gears that relied on relieving the backfire force by allowing one of the gears to break its torque on the idler assy axle shaft and rotate. This torque was set far too high for this design to work properly. When the engine occasionally backfired, the force transmitted by the backfire had no place to go, except back in the direction of the starter motor. Because the idler gears couldn't rotate, side cases and starters would break. All the while, Yamaha insisted that there was no real problem and ignored customer complaints of broken motorcycles. Many people don't know this, but in mid-2003, Yamaha came out with an updated idler gear assy that had a much lower breakaway torque value. This updated idler gear assy has a "-!" added to the part number. I have one in my spare parts box.

Yamaha fixed the problem with the introduction of the 2004 WR450F. They changed the design of the idler gear assy and incorporated a free wheeling feature that allowed the force from a backfire to spin the idler gear backwards without engaging the starter motor gear. You can tell if a WR450F has the updated Torque Limiter Assy by looking at the cover over the idler gear. The 2003 original gear cover is flat, the 2004 and newer WR450F has a chamfered bulge in the cover to accommodate the longer axle on the updated gear assy. The starter motors for 2003, 2004, and 2005 all have the same part number, don't know about 2006, so they are all identical. The starter was never the cause of the sheared woodruff key probem.

The starter on the WR450F does have its little problems though. The starters don't spin the engine fast enough when the weather is cold and often you have to kick start the bike the first thing in the morning, after that the bike starts on the electric starter without any problem. Jetting may contribute to this situation.

Well, there is the short version of the sheared woodruff key problem.:banghead:

thanks for that explanation baja... I have pulled little bits of info from different places, you just strung it all together for me / us. Would you know the symptoms of a stuffed relay?... clicking?

No I'm sorry duke2au, My knowledge of electricity is very basic. I'm sure that there are many people on this forum that could work with you on your problem, though.

If you find a good deal on an 03 WR450, you also have the option to do like I did and remove the battery and starter gear(extremely easy) - the bike is so easy to start, I've never missed the e-start after 2 years without it, and you save a few pounds as well. If you don't mind spending the $, the starter upgrade takes care of it completely.

Hey Baja. I bought an 03 back in April. The original owner told me that he did not worry about the Woodruff key problem and never did anything with it. The original owner raced it for a total of 800 miles and I have put another 800 on it since then. I talked to the GM at the local dealer before I bought my this bike and he told me that if it has 800 miles with no problems then it would not be a problem. If mine was going to shear would it have done it by now and is there a way to see if my was the mid 03 updated version?

yeah I agree with not worring about the woodruff. Mine was re-torqued by a mechanic with the original owner and has not had the problem yet.. (touch wood). The bike has about 1000Klms on it.

Tarfele, all of these bikes are built in a few weeks at the beginning of the model year. The modified Idler Gear came out in mid- 2003. I looked at the original gear that I have in my spare gear box and there is no identification number on the part. Unless the previous owner made the modificaion, the chances of having a stock idler gear that is the updated version are probably slim to none.

Yes, I know people that have done nothing to their 2003 WR's and have not had any trouble. Plenty of people who have posted on this forum have had problems, however. It is at best, an inconvenient problem if it happens in your garage like it did to me and at the worst a very expensive, serious problem when the bike quits in a place where you can't push it out or the woodruff key shears and you crack a side case. As Dirty Harry once said, "How lucky do you feel?"

Bajafool summed it up pretty good. There really is no woodruff key problem, it's actually the starter idler gear. If you get a backfire WHILE starting, it may break the woodruff key because the idler gear in the starter does not freewheel backward. If you haven't had a problem, chances are you will not. I had no problems, but the '04 upgrade was cheap insurance IMO. As far as poor starter performance, the '04 upgrade will do nothing. I have found that proper technique and jetting (especially on the pilot circuit) is the best cure for poor starting.

Of course the thing to remember is there are people out there like me who have early 03 WR450's and have had no problems at all with the starter or woodruff key, I have over 6000 miles on my bike to date. You might consider the updates just for the piece of mind.

i won't be able to give as detailed description as bajafool (it should be archived) but there are problems with some '03 starters. after a period of time a lot of the starters developed dead spots. the starter would just click like a low battery. if you rocked the bike (in gear) enough to rotate the starter a little, it would usually turn. when the starter is taken apart and checked, you can find dead spots in the windings. mine has epoxy smeared all over the area the wires connect to the brush contact area. there was no way to clean or resolder the contact. on the shelf it went. there seems to be more '03 owners reporting the problem here than later models. probably another bug we helped yamaha find.

Mtrablue is correct. Some starters produced for the 2003 model WR450F appeared to have been manufactured on "Monday" after a long hard weekend. My first 2003 starter failed in less than 100 miles. It had a dead spot in the windings. When you tried to start the bike with the "magic button" nothing happened. If you moved the kick starter just a little bit and hit the start button, it would fire right up. Took the bike to the dealer and they changed out the starter under warranty. I did not have any problems after that. Given that all of these starters have the same part number from 2003 through 2005, it would seem that there was a quality problem on some of these early 2003 starters. Changing to a 2004 or 2005 starter therefore, does not gain you any improvement in features or design over the 2003 starter. You could possibly buy a new starter that was manufactured following better quality control procedures, but there is no way for you to know that. Also, you can't know the date of manufacture of the starter that you are buying. Thus, you could buy a new starter to replace you 2003 vintage starter that was also manufacutured in 2003, just like the starter you are replacing.

Hi Guys-

Thanks for the info in this thread. For the sake of the archives, I thought I would add a note about my experience.

I have an 03 WR450. I'm the 2nd owner. The bike probably has 3000-4000 miles on it. It had the recall "loctite" fix performed. Two days ago in Moab about 3 miles in on Poison Spider, it backfired and the woodruff key sheared. After that it would not start... Back at camp, I pulled the crankcase cover and found that the rotor nut was finger tight! I wonder if the dealer forgot to torque this nut when they performed the recall fix! Anyway, I got an english 1/8" woodruff key from carquest and filed it down to fit and was back on the trail.

I don't know if my woodruff key sheared due to the starter gear problem which caused the rotor nut to loosen or if the loose nut combined with the backfire/idler gear problem caused the woodruff key to shear. Either way, I'm doing the 2004 starter upgrade!

My starter just quit me. It would not engage. Local service suggested to replace the starter clutch and driven gear. I ordered the parts and upon installation I found the problem with the old clutch and fixed it for no cost. The roller bearings in the clutch are held in place by a small spring. The spring was messed up. I replaced the spring and it was good as new. I have a cheap used starter clutch if anyone needs one. Oh yes it is a 2003 wr450f. Good luck:ride:

I have a 03 Wr450 onwed from new in the UK.

Its now on its 3rd starter and 2nd starter gear. Fantastic bike but have removed the starter gear and just kick it now as I refuse to spend another £180 on a motor. My local dealer has been of little help, refusing to acknowledge there is a problem.

As with a lot of these competition bikes with starter motors the manufactuers fail to tell you that they are restarters to only be used when the bikes are warm.:mad:

:thumbsup: i have just bought a 2003 wr450 and it has a starter problem.it will kickstart fine but i think it will have to have the 2004 update. can you tell from looking at the serial # if it has had the woodruff key up date? i hear they have a punch mark just ahead of the serial # ?? the starter was supposably rebuilt but that might have been a sales pitch.it will start with the electric start when it wants to. seems to have a mind of its own. what is the latest torque value on the flywheel nut? will a dealership still honor any warranty on that flywheel issue? anyone know. thanks my email is gvlucky45@aol.com

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