no spark on 2003 wr450f

4 replies to this topic
  • tobias3

Posted February 11, 2012 - 02:19 PM


As I posted in a earlier post, Thie bike was last running fine. I quit for the day and put the bike in the barn. Five weeks later she would not fire. No spark at the plug. New plug,no spark. Ignition coils seem to test fine.The kill switch tests good.Ran tests on the alternator(stator coils, charging and lighting) and came up at .6 ohms instead oh the listed .2 - .4 ohms. The manual says that if the readings are 'much outside the values listed, change the coils'. Is this differance of .2 ohms considered much outside the values listed? The pulse generator test came up right where it was supposed to .I looked for worn or broken connections on the wiring, but that is a bit of a black hole to get into.If there was a short would the bike have kept going like it did and then not fire back up?
I saw a post on Thumper talk that suggested that the wr450 has problems with the stator retaining bolts often come loose. I could check that but don't really want to get into gaskets ( crank case cover) and all of that. Any ideas if this is something I should check? Or any other ideas?

Edited by tobias3, February 12, 2012 - 12:28 PM.

  • simon@vic

Posted February 11, 2012 - 04:03 PM


some 2003 wr450s had crank/keyway/flywheel failures. there was no torque limmeter in the electric start and the tapper was not correct and there was alot of broken cranks etc. when the bike sputtered it could sheer the crank/flywheel
som bikes got upgraded with 2004 parts. some bikes got green lock tight. some got nothing!!!!

if the flywheel is not spinning and the crank is then you wont have spark. but you also wont have a bike that charges.

tank it apart and tell us what you find.

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  • travertt

Posted February 13, 2012 - 09:21 AM


It does seem odd that it just stopped sparking for no reason after only 5 weeks of sitting.

My bike sits for 5 months every year (the joys of winter) and then fires up again without too much fuss.

I'm sure you've already checked this (considering all the other testing you've been doing)..but have you verified that the 10 AMP fuse under the seat is still operational? there a way to check your regulator/rectifier. I had to replace mine this winter...I was getting unregulated input to the lights and burning them out on every ride. After I replaced thwe reg/rect...the bike started MUCH better.

Might be worth a shot.

  • Bazzaboy7

Posted February 14, 2012 - 05:33 AM


Hi there - I had a similar problem with my 99 WR400.
When I bought it the same story was told by the previous owner.

It turned out that after a lot of investigations it was the flywheel ............. :bonk: Readings were all fine on the stator / coil etc.

The magnets had all disintegrated - they were still encased in the thin metal shield but were in hundreds of pieces.
Have you noticed any metallic crap in the oil ? May be worth checking although the fact that they are magnetic could mean that they stick to all the components in your gearbox and sump etc. :smirk:
Let us know what you find - If I were you I would not risk trying to turn it over too many times before you strip that side off - just in case there's metallic crap in there ..... :lol:


Posted March 26, 2015 - 10:38 AM



Guys can u have a look at the above link and give me your opinion. As I've got a very similar problem, regards Chris


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